Quantification of Mitral Regurgitation in Mitral Valve Prolapse by Three-Dimensional Vena Contracta Area: Derived Cutoff Values and Comparison With Two-Dimensional Multiparametric Approach

BACKGROUND

Echocardiographic grading of mitral regurgitation (MR) in mitral valve prolapse (MVP) is challenging. Three-dimensional (3D) vena contracta area (VCA) has been proposed as a valuable method. However, data defining the cutoff values of severity and validation in the subset of patients with MVP are scarce. The aim of this study was to validate the 3D VCA by 3D color-Doppler transesophageal echocardiography (TEE) in patients with MVP and to define the cutoff values of severity grading. The secondary aim was to compare 3D VCA to the effective regurgitant orifice area estimation by proximal isovelocity surface area (EROA-PISA) method.

METHODS

A total of 1,138 patients with at least moderate MR who underwent TEE were included. Three-dimensional VCA was measured, and the cutoff value and area under the curve (AUC) for the prediction of severe MR were estimated by receiver operating characteristic curve using a guideline-suggested multiparametric approach as the reference standard. In a subgroup of patients, 3D regurgitant volume (RV) and 3D fraction were calculated from mitral and left ventricular outflow tract stroke volumes to further validate 3D VCA against a 3D volumetric reference standard.

RESULTS

The optimal 3D VCA cutoff value for predicting severe MR was 0.45 cm2 (specificity, 0.87; sensitivity, 0.90) with an AUC of 0.95 using a multiparametric approach as reference. Three-dimensional VCA had a good linear correlation with EROA-PISA (r = 0.62, P < .05) with larger values compared to EROA-PISA (0.63 cm2 vs 0.44 cm2, P < .05). A cutoff of 0.50 cm2 (AUC of 0.84; sensitivity, 0.78; specificity, 0.78) predicts an EROA-PISA of 0.40 cm2. Three-dimensional VCA had a good linear correlation with 3D RV (r = 0.56, P < .01), with an AUC of 0.86 to predict a 3D fraction >50%.

CONCLUSIONS

The present study suggests 0.45 cm2 as the best cutoff value of 3D VCA to define severe MR in patients with MVP, showing an optimal agreement with the reference standard multiparametric approach and 3D RV.

Beyond the Cardiovascular Effects of Glucagon-like Peptide-1 Receptor Agonists: Body Slimming and Plaque Stabilization. Are New Statins Born?

Atherosclerosis is a chronic inflammatory disease characterized by lipid and inflammatory cell deposits in the inner layer of large- and medium-sized elastic and muscular arteries. Diabetes mellitus (DM) significantly increases the risk of cardiovascular diseases and the overall and cardiovascular mortality, and it is a pro-atherogenic factor that induces atherosclerosis development and/or accelerates its progression through a multifactorial process. Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are a new class of drugs, belonging to the armamentarium to fight type 2 DM, that have shown robust reductions in atherosclerotic events and all-cause mortality in all studies. Preclinical studies have shown that GLP-1RAs play a role in the immunomodulation of atherosclerosis, affecting multiple pathways involved in plaque development and progression. In this review, we wanted to explore the translational power of such preclinical studies by analyzing the most recent clinical trials investigating the atheroprotective effect of GLP-1RAs.

Glucose variability: a new risk factor for cardiovascular disease

AIMS AND DATA SYNTHESIS

Glucose variability (GV) is increasingly considered an additional index of glycemic control. Growing evidence indicates that GV is associated with diabetic vascular complications, thus being a relevant point to address in diabetes management. GV can be measured using various parameters, but to date, a gold standard has not been identified. This underscores the need for further studies in this field also to identify the optimal treatment.

CONCLUSIONS

We reviewed the definition of GV, the pathogenetic mechanisms of atherosclerosis, and its relationship with diabetic complications.

The long-term clinical course of moderate tricuspid regurgitation

BACKGROUND

To evaluate the long-term clinical outcome of a cohort of patients suffering from moderate tricuspid regurgitation (TR), regardless of its etiology.

METHODS

Clinical and echocardiographic follow-up were assessed in 250 patients diagnosed with moderate TR between January 2016 and July 2020. TR progression at follow-up was defined as TR grade increase to at least severe. The primary endpoint was all-cause death; secondary endpoints were cardiovascular (CV) death and the composite of heart failure (HF) hospitalization plus tricuspid valve (TV) intervention.

RESULTS

After a median follow-up of 3.6 years, TR progression occurred in 84 patients (34%). At multivariate analyses, atrial fibrillation (AF, OR 1.81, CI 1.01-3.29, p = 0.045) and right ventricular end-diastolic diameter (RVEDD, OR 2.19, CI 1.26-3.78, p = 0.005) were independent predictors of TR progression. The primary endpoint occurred in 59 patients (24%) and was significantly more frequent in the group with TR progression (p = 0.009). At multivariate analyses, chronic kideney disease (OR 2.80, CI 1.30-6.03, p = 0.009), left ventricular ejection fraction (OR 0.97, CI 0.94-0.99, p = 0.041) and TR progression (OR 2.32, CI 1.31-4.12, p = 0.004) were independent predictors of the primary outcome. Moreover, both the secondary endpoints of CV death and HF hospitalization plus TV intervention were more frequent in the TR progression group (p = 0.001 and p < 0.001, respectively).

CONCLUSIONS

Moderate TR progresses in a significant proportion of patients over a long-term follow-up, leading to a worse prognosis. TR progression is an independent determinant of hard clinical events and AF and RVEDD are associated with TR progression.

Effect of acute CORticosteroids on conduction defects after Transcatheter Aortic Valve Implantation: the CORTAVI study

AIMS

Conduction abnormalities, requiring a permanent pacemaker (PPM), are the most common electrical complications after transcatheter aortic valve implantation (TAVI). The exact mechanism for conduction system defects is not yet clear. The local inflammatory process and edema are thought to play a role in the development of electrical disorders. Corticosteroids are effective anti-inflammatory and antiedematous agents. We aim to investigate the potential protective effect of corticosteroids on conduction defects after TAVI.

METHODS

This is a retrospective study of a single center. We analyzed 96 patients treated with TAVI. Thirty-two patients received oral prednisone 50 mg for 5 days after the procedure. This population was compared with the control group. All patients were followed up after 2 years.

RESULTS

Of the 96 patients included, 32 (34%) were exposed to glucocorticoids after TAVI. No differences in age, preexisting right bundle branch block or left bundle branch block, or valve type were seen among patients exposed to glucocorticoids versus those who were unexposed. We observed no significant differences between the two groups in the overall frequency of new PPM implantations during hospitalization (12% vs. 17%, P  = 0.76). The incidence of atrioventricular block (AVB) (STx 9% vs. non-STx 9%, P  = 0.89), right bundle branch block (STx 6% vs. non-STx 11%, P  = 0.71), and left bundle branch block (STx 34% vs. non-STx 31%, P  = 0.9) was not significantly different between the STx and non-STx groups. At 2 years after TAVI, none of the patients had implanted PPM or had severe arrhythmias documented by 24-h Holter ECG or cardiac examination.

CONCLUSION

Oral prednisone treatment does not appear to significantly reduce the incidence of AVB requiring acute PPM implantation after TAVI.

Acute myocardial infarction in a patient with MELAS syndrome: a possible link?

The mitochondrial encephalomyopathy, lactic acidosis, and stroke (MELAS) syndrome is a mitochondrial disorder, commonly caused by m.3243A>G mutation in the MT-TL1 gene. It encodes for the mitochondrial leucine transfer RNA (tRNA Leu [UUR]), implicated in the translation of proteins involved in the assembly and function of mitochondrial complexes in the electron transport chain. The m.3243A>G mutation determines complex I (CI) deficiency, ultimately leading to NADH accumulation, higher rates of glycolysis in order to compensate for the reduced ATP production and increase in lactates, the end-product of glycolysis. Disruption of the oxidative phosphorylation function with an inability to produce sufficient energy results in multi-organ dysfunction, with high energy demanding cells, such as myocytes and neurons, being the most affected ones. Therefore, MELAS syndrome is characterized by a heterogeneous clinical spectrum. Here we report on a case of a 55-year-old man affected by MELA syndrome with no cardiovascular risk factors. He was admitted to our department because of a non ST-segment elevation myocardial infarction (NSTEMI). A coronary angioplasty of the posterior descending artery and of the left anterior descending artery was realized. Transthoracic echocardiography showed inferior and anterior left ventricular wall hypokinesis together with a moderate left ventricle hypertrophy. Cardiac involvement is reported in about a third of the patients and left ventricular hypertrophy (LVH) is the most common phenotype, with possible dilated cardiomyopathy in end-stage disease; brady- arrhythmias and tachy-arrhythmias are also frequently reported as well as Wolff- Parkinson-White (WPW) syndrome. Organ impairment and clinical manifestations depend on the heteroplasmy level of mutant DNA in cells that can differ among individuals, explaining why some patients present a more severe disease. A clear relationship between MELAS syndrome and atherosclerosis has never been established, however recently advocated. In vitro studies in MELAS patients have shown that higher mitochondrial ROS levels and increased expression of oxidative stress-related genes, as a consequence of complex I deficiency and disrupted electron transport, allow circulating LDL to be promptly oxidized into ox-LDL, contributing to endothelial dysfunction and atherosclerosis plaque formation. In light of the recent evidence suggesting a possible link between mitochondrial disorders and atherosclerosis, we speculate that MELAS syndrome may have played a role in the pathogenesis of coronary artery disease in our patient. Further investigations are needed to confirm a pathogenetic link.

Gut Microbiota Composition and Cardiovascular Disease: A Potential New Therapeutic Target?

A great deal of evidence has revealed an important link between gut microbiota and the heart. In particular, the gut microbiota plays a key role in the onset of cardiovascular (CV) disease, including heart failure (HF). In HF, splanchnic hypoperfusion causes intestinal ischemia resulting in the translocation of bacteria and their metabolites into the blood circulation. Among these metabolites, the most important is Trimethylamine N-Oxide (TMAO), which is responsible, through various mechanisms, for pathological processes in different organs and tissues. In this review, we summarise the complex interaction between gut microbiota and CV disease, particularly with respect to HF, and the possible strategies for influencing its composition and function. Finally, we highlight the potential role of TMAO as a novel prognostic marker and a new therapeutic target for HF.

Left atrial appendage occlusion in the absence of intraprocedural product specialist monitoring: is it time to proceed alone? Results from a multicenter real-world experience

Background

Percutaneous left atrial appendage occlusion (LAAO) presents many technical complex features, and it is often performed under the intraprocedural surveillance of a product specialist (PS). Our aim is to assess whether LAAO is equally safe and effective when performed in high-volume centers without PS support.

Methods

Intraprocedural results and long-term outcome were retrospectively assessed in 247 patients who underwent LAAO without intraprocedural PS monitoring between January 2013 and January 2022 at three different hospitals. This cohort was then matched to a population who underwent LAAO with PS surveillance. The primary end point was all-cause mortality at 1 year. The secondary end point was a composite of cardiovascular mortality plus nonfatal ischemic stroke occurrence at 1 year.

Results

Of the 247 study patients, procedural success was achieved in 243 patients (98.4%), with only 1 (0.4%) intraprocedural death. After matching, we did not identify any significant difference between the two groups in terms of procedural time (70 ± 19 min vs. 81 ± 30 min, p = 0.106), procedural success (98.4% vs. 96.7%, p = 0.242), and procedure-related ischemic stroke (0.8% vs. 1.2%, p = 0.653). Compared to the matched cohort, a significant higher dosage of contrast was used during procedures without specialist supervision (98 ± 19 vs. 43 ± 21, p < 0.001), but this was not associated with a higher postprocedural acute kidney injury occurrence (0.8% vs. 0.4%, p = 0.56). At 1 year, the primary and the secondary endpoints occurred in 21 (9%) and 11 (4%) of our cohort, respectively. Kaplan-Meier curves showed no significant difference in both primary (p = 0.85) and secondary (p = 0.74) endpoint occurrence according to intraprocedural PS monitoring.

Conclusions

Our results show that LAAO, despite the absence of intraprocedural PS monitoring, remains a long-term safe and effective procedure, when performed in high-volume centers.

Advances in Imaging for Tricuspid Transcatheter Edge-to-Edge Repair: Lessons Learned and Future Perspectives

Severe tricuspid valve (TV) regurgitation (TR) has been associated with adverse long-term outcomes in several natural history studies, but isolated TV surgery presents high mortality and morbidity rates. Transcatheter tricuspid valve interventions (TTVI) therefore represent a promising field and may currently be considered in patients with severe secondary TR that have a prohibitive surgical risk. Tricuspid transcatheter edge-to-edge repair (T-TEER) represents one of the most frequently used TTVI options. Accurate imaging of the tricuspid valve (TV) apparatus is crucial for T-TEER preprocedural planning, in order to select the right candidates, and is also fundamental for intraprocedural guidance and post-procedural follow-up. Although transesophageal echocardiography represents the main imaging modality, we describe the utility and additional value of other imaging modalities such as cardiac CT and MRI, intracardiac echocardiography, fluoroscopy, and fusion imaging to assist T-TEER. Developments in the field of 3D printing, computational models, and artificial intelligence hold great promise in improving the assessment and management of patients with valvular heart disease.

Evolution of interventional imaging in structural heart disease

Treatments for structural heart diseases (SHD) have been considerably evolved by the widespread of transcatheter approach in the last decades. The progression of transcatheter treatments for SHD was feasible due to the improvement of devices and the advances in imaging techniques. In this setting, the cardiovascular imaging is pivotal not only for the diagnosis but even for the treatment of SHD. With the aim of fulfilling these tasks, a multimodality imaging approach with new imaging tools for pre-procedural planning, intra-procedural guidance, and follow-up of SHD was developed. This review will describe the current state-of-the-art imaging techniques for the most common percutaneous interventions as well as the new imaging tools. The imaging approaches will be addressed describing the use in pre-procedural planning, intra-procedural guidance, and follow-up.

Coronary Obstruction during Valve-in-Valve Transcatheter Aortic Valve Replacement: Pre-Procedural Risk Evaluation, Intra-Procedural Monitoring, and Follow-Up

Valve-in-valve (ViV) transcatheter aortic valve replacement (TAVR) is emerging as an effective treatment for patients with symptomatically failing bioprosthetic valves and a high prohibitive surgical risk; a longer life expectancy has led to a higher demand for these valve reinterventions due to the increased possibilities of outliving the bioprosthetic valve's durability. Coronary obstruction is the most feared complication of valve-in-valve (ViV) TAVR; it is a rare but life-threatening complication and occurs most frequently at the left coronary artery ostium. Accurate pre-procedural planning, mainly based on cardiac computed tomography, is crucial to determining the feasibility of a ViV TAVR and to assessing the anticipated risk of a coronary obstruction and the eventual need for coronary protection measures. Intraprocedurally, the aortic root and a selective coronary angiography are useful for evaluating the anatomic relationship between the aortic valve and coronary ostia; transesophageal echocardiographic real-time monitoring of the coronary flow with a color Doppler and pulsed-wave Doppler is a valuable tool that allows for a determination of real-time coronary patency and the detection of asymptomatic coronary obstructions. Because of the risk of developing a delayed coronary obstruction, the close postprocedural monitoring of patients at a high risk of developing coronary obstructions is advisable. CT simulations of ViV TAVR, 3D printing models, and fusion imaging represent the future directions that may help provide a personalized lifetime strategy and tailored approach for each patient, potentially minimizing complications and improving outcomes.

Treatment of HFpEF beyond the SGLT2-Is: Does the Addition of GLP-1 RA Improve Cardiometabolic Risk and Outcomes in Diabetic Patients?

Heart failure with preserved ejection fraction (HFpEF) is a common clinical syndrome frequently seen in elderly patients, the incidence of which is steadily increasing due to an ageing population and the increasing incidence of diseases, such as diabetes, hypertension, obesity, chronic renal failure, and so on. It is a multifactorial disease with different phenotypic aspects that share left ventricular diastolic dysfunction, and is the cause of about 50% of hospitalizations for heart failure in the Western world. Due to the complexity of the disease, no specific therapies have been identified for a long time. Sodium-Glucose Co-Transporter 2 Inhibitors (SGLT2-Is) and Glucagon-Like Peptide Receptor Agonists (GLP-1 RAs) are antidiabetic drugs that have been shown to positively affect heart and kidney diseases. For SGLT2-Is, there are precise data on their potential benefits in heart failure with reduced ejection fraction (HFrEF) as well as in HFpEF; however, insufficient evidence is available for GLP-1 RAs. This review addresses the current knowledge on the cardiac effects and potential benefits of combined therapy with SGLT2-Is and GLP-1RAs in patients with HFpEF.

Biomolecular Mechanisms of Cardiorenal Protection with Sodium-Glucose Co-Transporter 2 Inhibitors

Diabetes mellitus (DM) is a metabolic disorder characterized by chronic hyperglycemia and associated with an increased risk of morbidity and mortality, primarily from cardiovascular and renal diseases. Sodium-glucose cotransporter 2 inhibitors (SGLT2-Is) are novel drugs for the treatment of type 2 DM and heart failure (HF). SGLT2-Is mediate protective effects on both the renal and cardiovascular systems. This review addresses the current knowledge on the biomolecular mechanisms of the cardiorenal protective effects of SGLT2-Is, which appear to act mainly through non-glucose-mediated pathways. Cardiorenal protection mechanisms lead to reduced chronic renal disease progression and improved myocardial and coronary endothelial function. Concomitantly, it is possible to observe reflected changes in biomarkers linked with diabetic kidney disease and HF.

Combined MitraClip and Left Atrial Appendage Occlusion: Is It Still a Utopia?

Atrial fibrillation (AF) is the most common cardiac arrhythmia, affecting 32 million individuals worldwide, particularly the elderly. It is the main cause of ischemic strokes. Oral anticoagulation (OAC) is the gold standard strategy for stroke prevention. Still, there is a not negligible share of patients who have contraindications to this therapy, more frequently due to an increased risk of bleeding. AF is often associated with moderate-severe mitral regurgitation (MR), the second most frequent valvular disease in elderly patients. Data from the literature reported that more than half of patients with severe mitral regurgitation are not suitable candidates for cardiac surgery. Given the progressive aging of the population and the simultaneous increase in the number of patients with comorbidities, the advent of new therapeutic strategies, such as the combined approach of Left Atrial Appendage Occlusion (LAAO) and MitraClip procedure, is acquiring great interest. At present, the category of patients who may benefit from combined percutaneous therapies and the long-term risks and benefits might not have been identified. Despite the efforts of researchers, the correct selection of patients is a very important clinical need that has not yet been met to avoid committing human and financial resources to interventions that may be unnecessary. It is conceivable that the most modern and recent innovations in cardiovascular imaging, particularly three-dimensional echocardiography and new methods of volume imaging, could improve our ability to select patients appropriately. Since data in the literature are scarce, future studies will be needed to evaluate the efficacy and safety of combined MitraClip and LAA occlusion.

Accuracy and reliability of left atrial appendage morphology assessment by new 3D transesophageal echocardiographic rendering modalities: a comparative study with computed tomography

Funding Acknowledgements

Type of funding sources: None.

Background/Introduction. Left atrial appendage (LAA) morphology assessed by contrast-enhanced computed tomography (CT) has been associated to the risk of cardioembolic stroke in non-valvular atrial fibrillation. Subsequent studies with the traditional LAA classification system (CS) into 4 morphologies (Chicken wing, Cauliflower, Cactus and Windsock) yielded mixed results in terms of reliability and stroke risk association. Recently, a simple LAA morphology CS (new-LAAcs) based on the LAA bend angle measurement has been suggested. Three-dimensional transesophageal echocardiography (3D TOE) quality imaging has been improved and new volume rendering modalities developed.

Purpose. Aim of this study was to evaluate the accuracy and reliability of 2D and new 3D TOE rendering modalities compared to CT in assessing LAA morphology. We used and validated a new simple LAA morphology classification system (new-LAAcs) based on the LAA bend angle in contrast to the traditional CS.

Methods. 50 consecutive patients who underwent both cardiac CT and TOE were enrolled. LAA morphology was assessed by three different TEE modalities: (1) 2D TOE inspective evaluation (2D TOE), (2) 3D TOE multiplanar reconstruction (3D TOE MPR) and (3) 3D TOE Philips TrueVue Glass rendering (3D TOE GLASS). We assessed TOE accuracy compared to CT by sensitivity, specificity, accuracy, and Cohen’s kappa. Two trained readers independently adjudicated LAA morphologies in the new-LAAcs and the inter-rater reliability was obtained by percentage agreement and Cohen’s kappa. The reliability of the new- vs. traditional-LAAcs was assessed by CT in terms of reliability rates and influence on LAA morphology prevalence.

Results. CT and TOE imaging analyses were feasible in all patients. 2D TOE was fairly accurate in identifying LAA morphology (κ 0.38, p = 0.022) and had only moderate inter-rater (κ 0.46, p = 0.027) and substantial intra-rater (κ 0.62, p = 0.003) reliability rates. 3D TOE showed high validity: 3D TOE MPR had an almost perfect accuracy (κ 0.84, p &lt; 0.001) and substantial (κ 0.77, p &lt; 0.001) inter-rater reliability; 3D TOE GLASS substantial accuracy (κ 0.67, p &lt; 0.001) and almost perfect (κ 0.82, p &lt; 0.001) inter-rater reliability. Intra-rater agreement was almost perfect for both 3D TOE modalities (κ 0.84, p &lt; 0.001). In the comparison among CS the traditional-LAAcs inter-rater reliability was moderate (κ 0.47, p &lt; 0.001) and the intra-rater reliability substantial (κ 0.68, p &lt; 0.001) while the new-LAAcs yielded an almost perfect reliability level (inter-rater κ 0.84, p &lt; 0.001 and intra-rater κ 0.93, p &lt; 0.001). With the traditional-LAAcs, the prevalence of CW LAA was 30 (60%), while with the new-LAAcs the prevalence of low-risk-LAA was 13 (26%), leading to classify 17 (57%) CW morphologies as high-risk-LAA.

Conclusions. 3D TOE is an accurate, reliable, and feasible alternative to CT in assessing LAA morphology with the new-LAAcs. The new-LAAcs shows higher reliability rates than the traditional one. Abstract Figure.  Abstract Figure.

733 Evaluation of pulmonary pressures in patients underwent to MitraClip

Mitral regurgitation (MR) is the second most frequent valve heart disease in Europe and its underlying mechanism primary-organic (due to disease of the mitral leaflets), or secondary-functional (where valve leaflets and chordae are structurally normal and MR results from alterations in left ventricle and left atrium geometry), determines the therapeutic approach. Transcatheter Edge-to-Edge Repair (TEER) with MitraClip implantation is a minimal-invasive treatment that according to 2021 ESC Guidelines should be considered (class indication IIa) in selected symptomatic patients with severe MR despite optimal medical therapy, not eligible for surgery and fulfilling COAPT trial inclusion criteria, suggesting an increased chance of responding to treatment. Optimal valve morphology features for TEER are central pathology (second scallop), no leaflet calcifications, mitral valve area &gt;4 cm2, mobile length of posterior leaftel &gt;10 mm, coaptation depth &lt;11mm, normal leaflet strength and mobility, flail width &lt;15 mm, flail gap &lt;10 mm. TEER may be considered (class IIb) only in selected cases when the COAPT criteria are not fulfilled with the aim of improving symptoms and quality of life. MR occurs during systole, that at normal heart rates represents 30–50% of the cardiac cycle. As such, marked left atrial (LA) pressure elevation is present only transiently, representing less of a drive to development of secondary pulmonary hypertension compared to chronic LA pressure elevation seen in severe mitral stenosis. Anyway, in patients with severe MR echocardiography often reveals elevated systolic pulmonary artery pressure (PAPs) and MitraClip implantation usually is associated with a slight increase of the trans-mitral gradient with possible repercussions on pulmonary pressures. To better describe the effect of MitraClip implantation on pulmonary pressures and clinical outcomes we did a retrospective study enrolling in the period 2012–2021 25 patients with severe mitral regurgitation treated with TEER. We aimed to evaluate the clinical outcomes (symptoms, signs of heart failure, NYHA functional class) and the pulmonary pressures assessed by an echocardiographic examination before and after the intervention. At 6-month follow-up all patients with repaired mitral regurgitation showed an improvement in the NYHA class (from IV to II) and no need for re-hospitalization. We observed a trend in the reduction of the mean sistolic pulmonary arterial pressure of 2.68 mmHg ± 15 mmHg (P 0.39, 95% C.I. −9.03 to 3.67) with an unchanged left ventricle ejection fraction. Moreover, the echocardiographic exam showed a normalization of the S and D waves pattern in the pulmonary veins at the PW Doppler evaluation. We can assume that the clinical improvement and the reduction of dyspnoea in these patients underwent TEER is related to a reduction of pressures in the pulmonary circulation regardless of the ejection fraction. This finding could be used as a tool that the cardiologist has to evaluate in the echocardiography lab to reveal a new mitral valve disfunction. Considering the small sample, a greater number of patients will be enrolled to highlight the statistical significance.

Subclinical myocardial dysfunction in patients recovered from COVID-19

Background

Myocardial injury (MI) can be detected during the acute phase of Coronavirus disease 19 (COVID‐19) and is associated with a dismal prognosis. Recent imaging studies described the persistence of cardiac abnormalities after the recovery. The aim of the study was to investigate the spectrum of cardiac abnormalities at mid‐term follow‐up in patients recovered from COVID‐19 using clinical assessment, laboratory tests, and imaging evaluation with comprehensive echocardiography.

Methods

This is an observational, cross‐sectional study assessing an unselected cohort of consecutive patients recovered from COVID‐19. MI was defined by elevated plasma levels of high sensitive troponin T (hsTnT). At the follow‐up, a complete examination including echocardiography was performed.

Results

The 123 patients included were divided into two groups according to the presence of MI during hospitalization: group A (without MI) and group B (with MI). After a median of 85 days, group B patients were more frequently symptomatic for dyspnea and had significantly higher values of hsTnT and N‐Terminal prohormone of Brain Natriuretic Peptide (NT‐proBNP), compared to Group A. No differences between the two groups in left nor right ventricle dimension and ejection fraction were found. However, in group B a significant reduction of mean left ventricle global longitudinal strain was observed (‐15.7±.7 vs ‐18.1± .3 in group A, p < 0.001), together with higher frequency of impaired diastolic function and higher values of pulmonary pressure.

Conclusions

In patients recovered from COVID‐19, echocardiography with speckle‐tracking analysis may be an useful imaging tool to identify subclinical myocardial dysfunction and potentially guide management strategies.

Effect of the spatial-temporal specific theca cell Cyp17 overexpression on the reproductive phenotype of the novel TC17 mouse

Background

In the ovarian follicle, the Theca Cells (TCs) have two main functions: preserving morphological integrity and, importantly, secreting steroid androgen hormones. TCs express the essential enzyme 17α-hydroxylase/17,20-desmolase (CYP17), which permits the conversion of pregnenolone and progesterone into androgens. Dysregulation of CYP17 enzyme activity due to an intrinsic ovarian defect is hypothesized to be a cause of hyperandrogenism in women. Androgen excess is observed in women with polycystic ovary syndrome (PCOS) resulting from excess endogenous androgen production, and in transgender males undergoing exogenous testosterone therapy after female sex assignment at birth. However, the molecular and morphological effects of Cyp17 overexpression and androgen excess on folliculogenesis is unknown.

Methods

In this work, seeking a comprehensive profiling of the local outcomes of the androgen excess in the ovary, we generated a transgenic mouse model (TC17) with doxycycline (Dox)-induced Cyp17 overexpression in a local and temporal manner. TC17 mice were obtained by a combination of the Tet-dependent expression system and the Cre/LoxP gene control system.

Results

Ovaries of Dox-treated TC17 mice overexpressed Cyp17 specifically in TCs, inducing high testosterone levels. Surprisingly, TC17 ovarian morphology resembled the human ovarian features of testosterone-treated transgender men (partially impaired folliculogenesis, hypertrophic or luteinized stromal cells, atretic follicles, and collapsed clusters). We additionally assessed TC17 fertility denoting a perturbation of the normal reproductive functions (e.g., low pregnancy rate and numbers of pups per litter). Finally, RNAseq analysis permitted us to identify dysregulated genes (Lhcgr, Fshr, Runx1) and pathways (Extra Cellular Matrix and Steroid Synthesis).

Conclusions

Our novel mouse model is a versatile tool to provide innovative insights into study the effects of Cyp17 overexpression and hyperandrogenism in the ovary.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-03103-x.

FOXO1 Mitigation of FOXL2C143W/SMAD3 Transcriptomic Landscape in a Model of Granulosa Cell Tumor

Background: Adult granulosa cell tumor (aGCT) is a rare type of stromal cell malignant cancer of the ovary. Postmenopausal genital bleeding is the main aGCT clinical sign which is attributed to estrogen excess driven by CYP19 upregulation. Typically, aGCTs that are diagnosed at an initial stage can be treated with surgery. However, recurrences are mostly fatal¹. Current studies are focused on finding new molecular markers and targets that aim to treat the aGCTs recurrence. Between 95-97% of aGCTs harbor a somatic mutation in the FOXL2 gene, Cys134Trp (c.402C<G)². A TGF-β pathway protein, SMAD3, was identified as an essential partner in FOXL2^C134W transcriptional activity driving CYP19 upregulation³. Recently, the antitumoral FOXO1 gene has been recognized as a potential target for suppressing the FOXL2^C134W pathogenic action⁴. Aim: The objective of this study was to examine whether FOXO1 upregulation affects the FOXL2^C143W/SMAD3 transcriptomic landscape. Methods: RNA-seq analysis was performed comparing the effect of FOXL2^WT/SMAD3 and FOXL2^C143W/SMAD3 overexpression in presence of FOXO1 by transfection of an established human GC line (HGrC1). RNA-seq libraries were prepared using the illumina TrueSeq and sequenced using an illumina HiSeq Platform4000. To quantify transcript abundance for each sample we used salmon (1.1.0) with default parameters, using indexes from hg38. Data was subsequently imported in R using the tximport package and processed with the DESeq2 package. Results: RNA-seq data show that FOXL2^C143W/SMAD3 significantly drives 717 genes compared with the WT and enabled us to identify targets (TGFB2, SMARCA4, HSPG2, MKI67, NFKBIA) and neoplastic pathways directly associated with the mutant. To provide evidence that the differences in gene expression were attributed to a direct consequence of FOXL2 binding, we annotated gene promoters with previously published FOXL2 ChIP-seq analysis. The majority (73-40%) of the differential expressed genes (DEGs) between FOXL2^C134W and FOXL2^WT had a FOXL2 binding site at their promoters, which was a significantly higher proportion than in non-DEGs (Fisher’s exact test, murine: p= 7.9x10^-157; human, p= 9.9x10^-39). Surprisingly, the number of DEGs between FOXL2^C134W + FOXO1 and FOXL2^WT was much lower (230) with respect to the number of DEGs between FOXL2^C134W and FOXL2^WT (717, of which 130 in common; linear regression slope ß = 0 .58), suggesting that the effect of FOXL2^C134W compared with FOXL2^WT is moderated by the addition of FOXO1. Conclusions: Our transcriptomic study provides the first evidence that FOXO1 can efficiently mitigate 40% of the altered genome-wide effect specifically related to FOXL2^C134W in a model of human aGCT.1 Farkkila, A. et al. Ann Med (2017). 2 Jamieson, S. & Fuller, P. J. Endocr Rev (2012). 3 Belli, M. et al. Endocrinology (2018). 4 Belli, M et al. J Endocr Soc (2019).

A Novel Mouse Model for Studying the Effects of Cyp17 Overexpression in a Temporal- and Spatial-Specific Manner

Background: Cyp17 plays a key role in theca cells (TCs) to produce androgens, which, in turn, are converted to estrogens in granulosa cells. Intrinsic alterations in ovarian steroidogenesis contribute to excessive ovarian androgen production that characterizes polycystic ovary disease (PCOS)1,2. Hyperandrogenism has been associated with higher levels of Cyp17 in TCs, and correlate with increased numbers of antral follicles3. While androgen excess is one of the hallmark features of PCOS, its putative role in the follicular development and function remains poorly known. Most efforts have used androgen administration or Cyp19 blockade approach to study how androgens prolong folliculogenesis4. Although some insights have been made, it is not clear if these models accurately address the cascade of effects that follow ovarian hyperandrogenism. Aim: Here, we aim to study the specific effects of hyperandrogenemia on ovarian morphology, follicle function and fertility with a new transgenic (TG) mouse model expressing elevated Cyp17 levels exclusively in TCs. Methods: We generated a breeding line of triple TG mice using a combination of the Tet-dependent expression system and the Cre/LoxP gene control system. Specifically, we used Cyp17 promoter-iCre mice crossed with trans-activator mice (R26-STOP-rtTA-IRES-EGFP transgene, Jackson Lab) and with a responder mouse carrying the TRE-Cyp17 transgene. Cyp17 promoter-iCre mice were used to ensure rtTA/EGFP is expressed specifically in TCs of secondary follicles. After the DNA segment between the two LoxP sites is excised by Cyp17iCre specifically in TCs, the R26-STOP-rtTA gene remains activated in all daughter TCs. Only upon treatment with Doxycycline (DOX) can suppression be relieved and active transcription of TRE-Cyp17 be induced in a dose-dependent manner. Results: Cyp17 mRNA expression levels in TCs of TG mice treated with 20, 100 or 200 mg/Kg DOX compared with corresponding untreated control mice showed a modulation in a dose-dependent manner (P=0.01 ANOVA). Confocal and RNAscope analysis validated (i) the effective combination of the Cyp17iCre/rtTA expression system visualizing the rtTA/EGFP specifically expressed in ovarian TCs and (ii) the DOX-induced increase of Cyp17 expression compared with the WT mice. DOX treated TG females were acyclic, being mostly arrested in diestrus. Analysis of estrous cycle stages revealed that treated TG females spent significantly more time in diestrus than control females (P=0.007, ANOVA). Conclusions: Our new in vivo model is the first that analyzes androgen impact independent of any extraovarian source of androgen, complementing current clinical efforts to study the occurrences of TCs elevated androgen levels in normal and PCOS women. 1 Rosenfield, R. L. et al. Endocr Rev (2016)2 Azziz, R. et al. Nat Rev Dis Primers (2016)3 Comim, F. V., et al. Hum Reprod (2013)4 Stener-Victorin, E. et al. Endocr Rev (2020)

FOXO1 mitigates the SMAD3/FOXL2C134W transcriptomic effect in a model of human adult granulosa cell tumor

BACKGROUND

Adult granulosa cell tumor (aGCT) is a rare type of stromal cell malignant cancer of the ovary characterized by elevated estrogen levels. aGCTs ubiquitously harbor a somatic mutation in FOXL2 gene, Cys134Trp (c.402C < G); however, the general molecular effect of this mutation and its putative pathogenic role in aGCT tumorigenesis is not completely understood. We previously studied the role of FOXL2C134W, its partner SMAD3 and its antagonist FOXO1 in cellular models of aGCT.

METHODS

In this work, seeking more comprehensive profiling of FOXL2C134W transcriptomic effects, we performed an RNA-seq analysis comparing the effect of FOXL2WT/SMAD3 and FOXL2C134W/SMAD3 overexpression in an established human GC line (HGrC1), which is not luteinized, and bears normal alleles of FOXL2.

RESULTS

Our data shows that FOXL2C134W/SMAD3 overexpression alters the expression of 717 genes. These genes include known and novel FOXL2 targets (TGFB2, SMARCA4, HSPG2, MKI67, NFKBIA) and are enriched for neoplastic pathways (Proteoglycans in Cancer, Chromatin remodeling, Apoptosis, Tissue Morphogenesis, Tyrosine Kinase Receptors). We additionally expressed the FOXL2 antagonistic Forkhead protein, FOXO1. Surprisingly, overexpression of FOXO1 mitigated 40% of the altered genome-wide effects specifically related to FOXL2C134W, suggesting it can be a new target for aGCT treatment.

CONCLUSIONS

Our transcriptomic data provide novel insights into potential genes (FOXO1 regulated) that could be used as biomarkers of efficacy in aGCT patients.

FOXO1 Negates the Cooperative Action of FOXL2C134W and SMAD3 in CYP19 Expression in HGrC1 Cells by Sequestering SMAD3

Adult granulosa cell tumor (aGCT) is a rare type of ovarian cancer characterized by estrogen excess. Interestingly, only the single somatic mutation FOXL2 ^C134W was found across virtually all aGCTs. We previously reported that FOXL2^C134W stimulates CYP19 transcription synergistically with SMAD3, leading to elevated estradiol synthesis in a human granulosa cell line (HGrC1). This finding suggested a key role for FOXL2^C134W in causing the typical estrogen overload in patients with aGCTs. We have now investigated the effect of FOXO1, a tumor suppressor, on CYP19 activation by FOXL2^C134W in the presence of SMAD3. Intriguingly, FOXO1 antagonized the positive, synergistic effect of FOXL2^C134W and SMAD3 on CYP19 transcription. Similar to FOXL2^C134W, FOXO1 binds SMAD3 but not the proximal FOXL2^C134W binding site (-199 bp) of the CYP19 promoter identified in our earlier studies. The results of a competitive binding assay suggested a possible underlying mechanism in which FOXO1 sequesters SMAD3 away from FOXL2^C134W, thereby negating the cooperative action of FOXL2^C134W and SMAD3 in inducing CYP19 expression. To our knowledge, this study is the first to demonstrate the ability of FOXO1 to restore an altered CYP19 expression by FOXL2^C134W and SMAD3 and provides insight as to why FOXO1 deficiency promotes GCT development in mice.

Adjuvant Systemic Therapies in Patients with Colorectal Cancer: An Audit on Clinical Practice in Italy

Aims and Background

Rarely are conclusions from clinical trials summarized in international consensus conferences and promptly transferred to patient care. The adjuvant therapy for colorectal cancer used in daily clinical practice in Italy is described and compared with the recommendations of the 1990 NIH Consensus Conference.

Patients and Methods

We audited prescriptions of adjuvant systemic therapies for Italian colorectal cancer patients in 82 centers during a fixed one-week period.

Results

Among 434 patients receiving adjuvant chemotherapy there were 139 (42.5%) colon cancer patients with N- and 169 (51.7%) with N+ regional nodal involvement. Treatment at academic centers, a young age, T4 and a low total number of lymph nodes removed at surgery were the factors potentially justifying the decision for adjuvant chemotherapy in stage II colon cancer patients. The most common chemotherapy used was a bolus of 5-fluorouracil/folinic acid for 6 months (75.8%). Adjuvant radiotherapy was not administered to 37 (38.5%) of 96 patients with stage II and III rectal cancer.

Conclusions

The study shows that a substantial proportion of patients on adjuvant treatment at a certain time point in a large enough sample of Italian centers are stage II (potential over-treatment) and that an under-treatment of stage II and III rectal cancer patients (lack of radiotherapy) occurs too often in daily clinical practice in this country.

Weekly Low Dose Epirubicin in Elderly Cancer Patients

Aims and background

The treatment of elderly patients with metastatic solid tumours is still a debated problem. Patients over 75 years are generally excluded from combination chemotherapy trials because of higher toxicity. Several clinical studies have shown that weekly low dose epirubicin is a well tolerated and effective treatment for elderly cancer patients (breast, prostate, lung).

Methods

We report a study of patients aged between 75 and 85 years affected by metastatic anthracyclines-sensible carcinomas, to assess the tolerance of epirubicin given weekly at a dose of 25 mg/m2.

Results

25 patients (13 males, 12 females; ECOG P.S. 0-2) entered the study and were evaluable for side effects. One-hundred and ninety-six cycles of therapy have been administered. Side effects were never severe. Mucositis (9 patients), leucopenia (7 patients), anemia (5 patients) were usually of grade 1 or 2. Grade 1 cardiotoxicity (tachycardia) was observed in only one case. Grade 3 toxicity consisted in anemia (1 patient) and mucositis (1 patient), while grade 4 toxicity never occurred. Nineteen patients were evaluable for response: 0 CR, 4 PR (1 lung, 3 breast), 8 SD (3 lung, 3 breast, 2 prostate) have been observed. Compliance was encouraging and the majority of patients showed a decrease in symptoms and an improvement in performance status.

Conclusions

Weekly low-dose epirubicin is a very well tolerated treatment in elderly cancer patients. In view of the negligible toxicity encountered, it could be of utility to test this regimen in patients aged 75 years or older, affected by anthracyclines-sensible metastatic tumors, also to assess activity.

FOXL2C134W-Induced CYP19 Expression via Cooperation With SMAD3 in HGrC1 Cells

Germline knockout studies in female mice demonstrated an essential role for forkhead box L2 (FOXL2) in early follicle development, whereas an inducible granulosa cell (GC)-specific deletion of Foxl2 in adults has shown ovary-to-testis somatic sex reprogramming. In women, over 120 different germline mutations in the FOXL2 gene have been shown to cause blepharophimosis/ptosis/epicantus inversus syndrome associated with or without primary ovarian insufficiency. By contrast, a single somatic mutation (FOXL2C134W) accounts for almost all adult-type GC tumors (aGCTs). To test the hypothesis that FOXL2C134W differentially regulates the expression of aGCT markers, we investigated the effect of FOXL2C134W on inhibin B and P450 aromatase expression using a recently established human GC line (HGrC1), which we now show to bear two normal alleles of FOXL2. Neither FOXL2wt nor FOXL2C134W regulate INHBB messenger RNA (mRNA) expression. However, FOXL2C134W selectively displays a 50-fold induction of CYP19 mRNA expression dependent upon activin A. Mechanistically, the CYP19 promoter is activated in a similar way by FOXL2C134W interaction with SMAD3, but not by FOXL2wt. SMAD2 had no effect. Moreover, FOXL2C134W interactions with SMAD3 and with the FOX binding element located at -199 bp upstream of the ATG initiation codon of CYP19 are more sustainable than FOXL2wt. Thus, FOXL2C134W potentiates CYP19 expression in HGrC1 cells via enhanced recruitment of SMAD3 to a proximal FOX binding element. These findings may explain the pathophysiology of estrogen excess in patients with aGCT.

A Neural Network-Based Identification of Developmentally Competent or Incompetent Mouse Fully-Grown Oocytes

Infertility clinics would benefit from the ability to select developmentally competent vs. incompetent oocytes using non-invasive procedures, thus improving the overall pregnancy outcome. We recently developed a classification method based on microscopic live observations of mouse oocytes during their in vitro maturation from the germinal vesicle (GV) to the metaphase II stage, followed by the analysis of the cytoplasmic movements occurring during this time-lapse period. Here, we present detailed protocols of this procedure. Oocytes are isolated from fully-grown antral follicles and cultured for 15 h inside a microscope equipped for time-lapse analysis at 37 °C and 5% CO2. Pictures are taken at 8 min intervals. The images are analyzed using the Particle Image Velocimetry (PIV) method that calculates, for each oocyte, the profile of Cytoplasmic Movement Velocities (CMVs) occurring throughout the culture period. Finally, the CMVs of each single oocyte are fed through a mathematical classification tool (Feed-forward Artificial Neural Network, FANN), which predicts the probability of a gamete to be developmentally competent or incompetent with an accuracy of 91.03%. This protocol, set up for the mouse, could now be tested on oocytes of other species, including humans.

Molecular Aspects and Clinical Relevance of GDF9 and BMP15 in Ovarian Function

Growth and differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15) are oocyte-secreted factors with a leading role in the control of ovarian function in female reproduction, modulating both the cell fate of the somatic granulosa cells and the quality and developmental competence of the egg. This short review aims to consolidate the molecular aspects of GDF9 and BMP15 and their integral actions in female fertility to understand particularly their effects on oocyte quality and fetal growth. The significant consequences of mutations in the GDF9 and BMP15 genes in women with dizygotic twins as well as the clinical relevance of these oocyte factors in the pathogenesis of primary ovarian insufficiency and polycystic ovary syndrome are also addressed.

Cytoplasmic movement profiles of mouse surrounding nucleolus and not-surrounding nucleolus antral oocytes during meiotic resumption

Full-grown mouse antral oocytes are classified as surrounding nucleolus (SN) or not-surrounding nucleolus (NSN), depending on the respective presence or absence of a ring of Hoechst-positive chromatin surrounding the nucleolus. In culture, both types of oocytes resume meiosis and reach the metaphase II (MII) stage, but following insemination, NSN oocytes arrest at the two-cell stage whereas SN oocytes may develop to term. By coupling time-lapse bright-field microscopy with image analysis based on particle image velocimetry, we provide the first systematic measure of the changes to the cytoplasmic movement velocity (CMV) occurring during the germinal vesicle-to-MII (GV-to-MII) transition of these two types of oocytes. Compared to SN oocytes, NSN oocytes display a delayed GV-to-MII transition, which can be mostly explained by retarded germinal vesicle break down and first polar body extrusion. SN and NSN oocytes also exhibit significantly different CMV profiles at four main time-lapse intervals, although this difference was not predictive of SN or NSN oocyte origin because of the high variability in CMV. When CMV profile was analyzed through a trained artificial neural network, however, each single SN or NSN oocyte was blindly identified with a probability of 92.2% and 88.7%, respectively. Thus, the CMV profile recorded during meiotic resumption may be exploited as a cytological signature for the non-invasive assessment of the oocyte developmental potential, and could be informative for the analysis of the GV-to-MII transition of oocytes of other species.

Evaluation of Symptoms and Prevention of Cancer in Menopause: The Value of Vulvar Exam

Vulvar and vaginal atrophy (VVA), is a chronic medical condition experienced by postmenopausal women, with prevalence estimated ranging from 10% to 50% [1]. VVA is characterized by a constellation of symptoms, that may affect daily activities, sexuality, relationships, and quality of life [3]. Early recognition and effective treatment of VVA may enhance sexual health and the quality of life of women and their partners. Some vulvar conditions such as lichen sclerosus are more prevalent in the postmenopausal years. Lichen sclerosus has been suggested as a precursor of Vulvar squamous cell carcinoma. The vulvar exam in post-menopausal women plays an essential role in prevention of cancer because it allows to identify women who should undergo vulvar skin biopsy in order to early detect pre-neoplastic lesions for early diagnosis of cancer of the vulva.

Results of a round-robin exercise on read-across

A round-robin exercise was conducted within the CALEIDOS LIFE project. The participants were invited to assess the hazard posed by a substance, applying in silico methods and read-across approaches. The exercise was based on three endpoints: mutagenicity, bioconcentration factor and fish acute toxicity. Nine chemicals were assigned for each endpoint and the participants were invited to complete a specific questionnaire communicating their conclusions. The interesting aspect of this exercise is the justification behind the answers more than the final prediction in itself. Which tools were used? How did the approach selected affect the final answer?

Glioblastoma stem cells: radiobiological response to ionising radiations of different qualities

Glioblastoma multiforme (GBM) is the most common and malignant primary brain tumour, with very poor prognosis. The high recurrence rate and failure of conventional treatments are expected to be related to the presence of radio-resistant cancer stem cells (CSCs) inside the tumour mass. CSCs can both self-renew and differentiate into the heterogeneous lineages of cancer cells. Recent evidence showed a higher effectiveness of C-ions and protons in inactivating CSCs, suggesting a potential advantage of Hadrontherapy compared with conventional radiotherapy for GBM treatment. To investigate the mechanisms involved in the molecular and cellular responses of CSCs to ionising radiations, two GBM stem cell (GSC) lines, named lines 1 and 83, which were derived from patients with different clinical outcomes and having different metabolic profiles (as shown by NMR spectroscopy), were irradiated with (137)Cs photons and with protons or C-ions of 62 MeV u(-1) in the dose range of 5-40 Gy. The biological effects investigated were: cell death, cell cycle progression, and DNA damage induction and repair. Preliminary results show a different response to ionising radiation between the two GSC lines for the different end points investigated. Further experiments are in progress to consolidate the data and to get more insights on the influence of radiation quality.

Low-radiation environment affects the development of protection mechanisms in V79 cells

Very little is known about the influence of environmental radiation on living matter. In principle, important information can be acquired by analysing possible differences between parallel biological systems, one in a reference-radiation environment (RRE) and the other in a low-radiation environment (LRE). We took advantage of the unique opportunity represented by the cell culture facilities at the Gran Sasso National Laboratories of the Istituto Nazionale di Fisica Nucleare, where environment dose rate reduction factors in the underground (LRE), with respect to the external laboratory (RRE), are as follows: 10(3) for neutrons, 10(7) for directly ionizing cosmic rays and 10 for total γ-rays. Chinese hamster V79 cells were cultured for 10 months in both RRE and LRE. At the end of this period, all the cultures were kept in RRE for another 6 months. Changes in the activities of antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT; glutathione peroxidase, GPX) and spontaneous mutation frequency at the hypoxanthine-guanine phosphoribosyl transferase (hprt) locus were investigated. The results obtained suggest that environmental radiation might act as a trigger of defence mechanisms in V79 cells, specifically those in reference conditions, showing a higher degree of defence against endogenous damage as compared to cells grown in a very low-radiation environment. Our findings corroborate the hypothesis that environmental radiation contributes to the development of defence mechanisms in today living organisms/systems.

Induction and Repair of DNA DSB as Revealed by H2AX Phosphorylation Foci in Human Fibroblasts Exposed to Low- and High-LET Radiation: Relationship with Early and Delayed Reproductive Cell Death

The spatial distribution of radiation-induced DNA breaks within the cell nucleus depends on radiation quality in terms of energy deposition pattern. It is generally assumed that the higher the radiation linear energy transfer (LET), the greater the DNA damage complexity. Using a combined experimental and theoretical approach, we examined the phosphorylation-dephosphorylation kinetics of radiation-induced γ-H2AX foci, size distribution and 3D focus morphology, and the relationship between DNA damage and cellular end points (i.e., cell killing and lethal mutations) after exposure to gamma rays, protons, carbon ions and alpha particles. Our results showed that the maximum number of foci are reached 30 min postirradiation for all radiation types. However, the number of foci after 0.5 Gy of each radiation type was different with gamma rays, protons, carbon ions and alpha particles inducing 12.64 ± 0.25, 10.11 ± 0.40, 8.84 ± 0.56 and 4.80 ± 0.35 foci, respectively, which indicated a clear influence of the track structure and fluence on the numbers of foci induced after a dose of 0.5 Gy for each radiation type. The γ-H2AX foci persistence was also dependent on radiation quality, i.e., the higher the LET, the longer the foci persisted in the cell nucleus. The γ-H2AX time course was compared with cell killing and lethal mutation and the results highlighted a correlation between cellular end points and the duration of γ-H2AX foci persistence. A model was developed to evaluate the probability that multiple DSBs reside in the same gamma-ray focus and such probability was found to be negligible for doses lower than 1 Gy. Our model provides evidence that the DSBs inside complex foci, such as those induced by alpha particles, are not processed independently or with the same time constant. The combination of experimental, theoretical and simulation data supports the hypothesis of an interdependent processing of closely associated DSBs, possibly associated with a diminished correct repair capability, which affects cell killing and lethal mutation.

OCT4 and the acquisition of oocyte developmental competence during folliculogenesis

The role that the transcription factor OCT4 plays during oocyte growth is yet unknown. In this review, we summarise the data on its potential role in the acquisition of oocyte developmental competence in the mouse. These studies describe the presence in MII oocytes and 2-cell embryos of an OCT4 transcriptional network that might be part of the molecular signature of maternal origin on which the inner cell mass and the embryonic stem cell-associated pluripotency is assembled and shaped. The Oct4-gene regulatory network thus provides a connection between eggs, early preimplantation embryos and embryonic stem cells.

MELODI: the 'Multidisciplinary European Low-Dose Initiative'

The importance of research to reduce uncertainties in risk assessment of low and protracted exposures is now recognised globally. In Europe a new initiative, called 'Multidisciplinary European LOw Dose Initiative' (MELODI), has been proposed by a 'European High Level and Expert Group on low-dose risk research' (www.hleg.de), aimed at integrating national and EC (Euratom) efforts. Five national organisations: BfS (DE), CEA (FR), IRSN (FR), ISS (IT) and STUK (FI), with the support of the EC, have initiated the creation of MELODI by signing a letter of intent. In the forthcoming years, MELODI will integrate in a step-by-step approach EU institutions with significant programmes in the field and will be open to other scientific organisations and stakeholders. A key role of MELODI is to develop and maintain over time a strategic research agenda (SRA) and a road map of scientific priorities within a multidisciplinary approach, and to transfer the results for the radiation protection system. Under the coordination of STUK a network has been proposed in the 2009 Euratom Programme, called DoReMi (Low-Dose Research towards Mutidisciplinary Integration), which can help the integration process within the MELODI platform. DoReMi and the First MELODI Open Workshop, organised by BfS in September 2009, are now important inputs for the European SRA.

Monte Carlo evaluation of DNA fragmentation spectra induced by different radiation qualities

The PARTRAC code has been developed constantly in the last several years. It is a Monte Carlo code based on an event-by-event description of the interactions taking place between the ionising radiation and liquid water, and in the present version simulates the transport of photons, electrons, protons, helium and heavier ions. This is combined with an atom-by-atom representation of the biological target, i.e. the DNA target model of a diploid human fibroblast in its interphase (genome of 6 Gigabase pairs). DNA damage is produced by the events of energy depositions, either directly, if they occur in the volume occupied by the sugar-phosphate backbone, or indirectly, if this volume is reached by radiation-induced radicals. This requires the determination of the probabilities of occurrence of DNA damage. Experimental data are essential for this determination. However, after the adjustment of the relevant parameters through the comparison of the simulation data with the DNA fragmentation induced by photon irradiation, the code has been used without further parameter adjustments, and the comparison with the fragmentation induced by charged particle beams has validated the code. In this paper, the results obtained for the DNA fragmentation induced by gamma rays and by charged particle beams of various LET are shown, with a particular attention to the production of very small fragments that are not detected in experiments.

Adaptive response: modelling and experimental studies

Adaptive response (AR) is a term that has been generally accepted to describe the ability of a low 'priming' radiation dose to decrease the cell response to a subsequent higher 'challenging' dose. The main proposed mechanisms to explain AR are: increased efficiency of DNA repair and induction of antioxidant enzymes. A model that considers a modulation of the efficiency of DNA repair activity and of the level of antioxidant enzymes, starting from the framework of a lethal-potentially lethal (LPL) model is proposed. The LPL model has been extended with the inclusion of the dynamic variables representing the efficiency of repair, the levels of radiation induced radicals and of antioxidant enzymes. The model used here is able to describe the protective effect of a priming dose. Moreover, in agreement with the data in the literature, the simulations show that the AR happens in given priming dose and priming dose-rate ranges only, and requires at least 4 h to develop. In order to get more insights into the role of cell-cell communication as factors affecting the AR, experimental studies were planned using sparse or confluent AG1522 cell monolayer. The results obtained after gamma irradiation suggest that cell density is a crucial factor for observing an AR.

DNA fragmentation in V79 cells irradiated with light ions as measured by pulsed‐field gel electrophoresis. II. Simulation with a generalized broken stick model

PURPOSE

To characterize the differences among the experimental DNA fragmentation spectra induced in Chinese hamster V79 cells by gamma-rays, low-energy protons and alpha-particles through the use of a phenomenological model.

MATERIALS AND METHODS

A model of DNA fragmentation was developed as a generalization of the broken-stick model, in which the double-strand breaks induced by radiation were considered randomly placed, but in which the manifestly non-random fragmentation of the control sample was fully taken into account and considered as the initial fragment distribution. Further, an analytical method was introduced that allowed an evaluation of the deviation from randomness of the fragmentation induced by radiation.

RESULTS

The analysis of the experimental distribution of DNA fragments showed that there was a progressive departure from randomness in radiation-induced fragmentation going from gamma-rays to protons and then to alpha-particles. This deviation was characterized by an enhanced induction of fragments, and therefore by a larger correlation of double-strand breaks, in the experimental range of lower molecular weights.

CONCLUSION

The analysis shows that low-energy light ions induce DNA fragmentation, at the loop level of the chromatin organization, that can be significantly non-random. The same analysis can readily be applied at different length scales, and thus it could offer a basis for the study of the link between DNA damage, correlated at various spatial scales and biological end-points.

Direct Comparison between Protons and Alpha-particles of the Same LET: I. Irradiation Methods and Inactivation of Asynchronous V79, HeLa and C3H 10T½ Cells

A direct comparison was carried out of the biological effectiveness of protons and alpha-particles of the same linear energy transfer (LET) under identical conditions with a variety of in vitro biological systems. Monolayers of mammalian cells were irradiated with accelerated beams of protons (1.2 and 1.4 MeV) and alpha-particles (30 and 35 MeV) corresponding to LETs of 23 and 20 keV microns-1 for each particle type. For V79-4 cells it was observed that the linear term of the dose-response for cell inactivation by protons was significantly greater than that for alpha-particles of the same LET. For HeLa and HeLa S3 cells, also, the linear term appeared to be greater for protons, but this was not observed with more limited data for C3H 10T1/2 cells. The result for V79 cells is in agreement with the report of Belli et al. (1989) who observed that the biological effectiveness of protons rose sharply between 17 and 30 keV microns-1 in strong contrast to alpha-particles which reached a peak effectiveness at greater than 100 keV microns-1. These results place new constraints on the biologically relevant features of the microscopic structure of radiation tracks, and have implications for the mechanistic and practical comparison between radiations.

Direct Comparison of Biological Effectiveness of Protons and Alpha-particles of the Same LET. II. Mutation Induction at the HPRT Locus in V79 Cells

Mutation induction at the hprt locus has been studied in V79-4 Chinese hamster cells irradiated with mono-energetic protons and alpha-particles with LET of 20.3 and 23 keV microns-1. The mutation frequency increased linearly with the dose for all the four radiation qualities investigated, so that effectiveness for mutation induction could be expressed by the slope of the relevant curve. This effectiveness did not significantly change with the small change in LET of each kind of particle, while sizeable differences were found between particles. Protons were more effective in mutation induction than alpha-particles with the same LET by a factor of about 2. This finding is similar to, although slightly larger than, the factors 1.5-1.8 found for inactivation of the same cells in the same series of experiments.