Early Appearance of Dendritic Alterations in Neocortical Pyramidal Neurons of the Ts65Dn Model of Down Syndrome.

Down syndrome (DS), which is due to triplication of chromosome 21, is constantly associated with intellectual disability (ID). ID can be ascribed to both neurogenesis impairment and dendritic pathology. These defects are replicated in the Ts65Dn mouse, a widely used model of DS. While neurogenesis impairment in DS is a fetal event, dendritic pathology occurs after the first postnatal months. Neurogenesis alterations across the life span have been extensively studied in the Ts65Dn mouse. In contrast, there is scarce information regarding dendritic alterations at early life stages in this and other models, although there is evidence for dendritic alterations in adult mouse models. Thus, the goal of the current study was to establish whether dendritic alterations are already present in the neonatal period in Ts65Dn mice. In Golgi-stained brains, we quantified the dendritic arbors of layer II/III pyramidal neurons in the frontal cortex of Ts65Dn mice aged 2 (P2) and 8 (P8) days and their euploid littermates. In P2 Ts65Dn mice, we found a moderate hypotrophy of the apical and collateral dendrites but a patent hypotrophy of the basal dendrites. In P8 Ts65Dn mice, the distalmost apical branches were missing or reduced in number, but there were no alterations in the collateral and basal dendrites. No genotype effects were detected on either somatic or dendritic spine density. This study shows dendritic branching defects that mainly involve the basal domain in P2 Ts65Dn mice and the apical but not the other domains in P8 Ts65Dn mice. This suggests that dendritic defects may be related to dendritic compartment and age. The lack of a severe dendritic pathology in Ts65Dn pups is reminiscent of the delayed appearance of patent dendritic alterations in newborns with DS. This similarly highlights the usefulness of the Ts65Dn model for the study of the mechanisms underlying dendritic alterations in DS and the design of possible therapeutic interventions.

Treatment with the flavonoid 7,8-Dihydroxyflavone: a promising strategy for a constellation of body and brain disorders.

Flavonoids have long been known to exert benefits in various health problems. Among them, the BDNF mimetic 7,8-Dihydroxyflavone (7,8-DHF) is emerging as a potential treatment for a constellation of brain and body pathologies. During the past 10 years, more than 180 preclinical studies have explored the efficacy of 7,8-DHF in animal models of different pathologies. The current review intends to be an exhaustive survey of these studies. By providing detailed information on the rationale of the experimental design and outcome of treatment, we will give the reader tools to critically interpret the achievement obtained so far. If we put together each individual piece of this complex mosaic, a picture emerges that is full of promise regarding the potential usefulness of 7,8-DHF for human treatment. Much has been done so far and we believe that the time is now ripe to move from the bench to the bedside, in order to establish whether supplementation with 7,8-DHF may serve as therapy or, at least, as adjuvant for the treatment of pathologies affecting brain and body functioning.

Complicated postoperative course in isolated tricuspid valve surgery: Looking for predictors.

BACKGROUND: This study aims at better defining the profile of patients with a complicated versus noncomplicated postoperative course following isolated tricuspid valve (TV) surgery to identify predictors of a favorable/unfavorable hospital outcome. METHODS: All patients treated with isolated tricuspid surgery from March 1997 to January 2020 at our institution were retrospectively reviewed. Considering the complexity of most of these patients, a regular postoperative course was arbitrarily defined as a length-of-stay in intensive care unit less than 4 days and/or postoperative length-of-stay less than 10days. Patients were therefore divided accordingly in two groups. RESULTS: One hundred and seventy-two patients were considered, among whom 97 (56.3%) had a regular (REG) and 75 (43.6%) a non-regular (NEG) postoperative course. The latter had worse baseline clinical and echocardiographic characteristics, with higher rate of renal insufficiency, previous heart failure hospitalizations, cardiac operations, and right ventricular dysfunction. NEG patients more frequently needed tricuspid replacement and experienced a greater number of complications (p < .001) and higher in-hospital mortality (13% vs. 0%, p < .001). The majority of these complications were related to more advanced stage of the tricuspid disease. Among most important predictors of a negative outcome univariate analysis identified chronic kidney disease, ascites, previous right heart failure hospitalizations, right ventricular dysfunction, previous cardiac surgeries, TV replacement and higher MELD scores. At multivariate analysis, liver enzymes and diuretics' dose were predictors of complicated postoperative course. CONCLUSION: In isolated TV surgery a complicated postoperative course is observed in patients with more advanced right heart failure and organ damage. Earlier surgical referral is associated to excellent outcomes and should be recommended.

The flavonoid 7,8-DHF fosters prenatal brain proliferation potency in a mouse model of Down syndrome.

Neurogenesis impairment is a key determinant of intellectual disability in Down syndrome (DS), a genetic pathology due to triplication of chromosome 21. Since neurogenesis ceases after birth, apart in the hippocampus and olfactory bulb, the only means to tackle the problem of neurogenesis impairment in DS at its root is to intervene during gestation. A few studies in DS mouse models show that this is possible, although the drugs used may raise caveats in terms of safety. We previously found that neonatal treatment with 7,8-dihydroxyflavone (7,8-DHF), a flavonoid present in plants, restores hippocampal neurogenesis in the Ts65Dn model of DS. The goal of the current study was to establish whether prenatal treatment with 7,8-DHF improves/restores overall brain proliferation potency. Pregnant Ts65Dn females received 7,8-DHF from embryonic day 10 until delivery. On postnatal day 2 (P2) the pups were injected with BrdU and were killed after either 2 h or 52-60 days (P52-60). Evaluation of the number of proliferating (BrdU+) cells in various forebrain neurogenic niches of P2 mice showed that in treated Ts65Dn mice proliferation potency was improved or even restored in most of the examined regions, including the hippocampus. Quantification of the surviving BrdU+ cells in the dentate gyrus of P52-60 mice showed no difference between treated and untreated Ts65Dn mice. At P52-60, however, treated Ts65Dn mice exhibited a larger number of granule cells in comparison with their untreated counterparts, although their number did not reach that of euploid mice. Results show that 7,8-DHF has a widespread impact on prenatal proliferation potency in Ts65Dn mice and exerts mild long-term effects. It remains to be established whether treatment extending into the neonatal period can lead to an improvement in brain development that is retained in adulthood.

Early appearance of developmental alterations in the dendritic tree of the hippocampal granule cells in the Ts65Dn model of Down syndrome.

Down syndrome (DS), a genetic condition caused by triplication of chromosome 21, is characterized by alterations in various cognitive domains, including hippocampus-dependent memory functions, starting from early life stages. The major causes of intellectual disability in DS are prenatal neurogenesis alterations followed by impairment of dendritic development in early infancy. While there is evidence that the Ts65Dn mouse, the most widely used model of DS, exhibits dendritic alterations in adulthood, no studies are available regarding the onset of dendritic pathology. The goal of the current study was to establish whether this model exhibits early dendritic alterations in the hippocampus, a region whose function is severely damaged in DS. To this purpose, in Golgi-stained brains, we evaluated the dendritic arborization and dendritic spines of the granule cells of the hippocampal dentate gyrus in Ts65Dn mice aged 8 (P8) and 15 (P15) days. While P15 Ts65Dn mice exhibited a notably hypotrophic dendritic arbor and a reduced spine density, P8 mice exhibited a moderate reduction in the number of dendritic ramifications and no differences in spine density in comparison with their euploid counterparts. Both in P8 and P15 mice, spines were longer and had a longer neck, suggesting possible alterations in synaptic function. Moreover, P8 and P15 Ts65Dn mice had more thin spines and fewer stubby spines in comparison with euploid mice. Our study provides novel evidence on the onset of dendritic pathology, one of the causes of intellectual disability in DS, showing that it is already detectable in the dentate gyrus of Ts65Dn pups. This evidence strengthens the suitability of this model of DS as a tool to study dendritic pathology in DS and to test the efficacy of early therapeutic interventions aimed at ameliorating hippocampal development and, therefore, memory functions in children with DS.

Neuroanatomical alterations in higher-order thalamic nuclei of fetuses with Down syndrome.

OBJECTIVES: Down syndrome (DS) is a genetic condition characterized by cognitive disability starting from infancy. Children with DS exhibit deficits in several cognitive domains, including executive function, i.e., a set of cognitive processes that heavily depend on higher-order thalamic nuclei. The goal of this study was to establish whether executive function-related thalamic nuclei of fetuses with DS exhibit neuroanatomical alterations that may contribute to the defects in higher-order control processes seen in children with DS. PATIENTS AND METHODS: In brain sections from fetuses with DS and control fetuses (gestational week 17-22), we evaluated the cellularity in the mediodorsal nucleus (MD), the centromedian nucleus (CM), and the parafascicular nucleus (PF) of the thalamus and the density of proliferating cells in the third ventricle. RESULTS: We found that all three nuclei had a notably reduced cell density. This defect was associated with a reduced density of proliferating cells in the third ventricle, suggesting that the reduced cellularity in the MD, CM, and PF of fetuses with DS was due to neurogenesis impairment. The separate evaluation of projection neurons and interneurons in the MD, CM, and PF showed that in fetuses with DS the density of projection neurons was reduced, with no changes in interneuron density. CONCLUSION: This study provides novel evidence for DS-linked cellularity alterations in the MD, CM, and PF and suggests that altered signal processing in these nuclei may be involved in the impairment in higher-order control processes observed in individuals with DS starting from infancy.

Neonatal therapy with clenbuterol and salmeterol restores spinogenesis and dendritic complexity in the dentate gyrus of the Ts65Dn model of Down syndrome.

Down syndrome (DS), a neurodevelopmental disorder caused by triplication of chromosome 21, is characterized by intellectual disability. In DS, defective neurogenesis causes an overall reduction in the number of neurons populating the brain and defective neuron maturation causes dendritic hypotrophy and reduction in the density of dendritic spines. No effective therapy currently exists for the improvement of brain development in individuals with DS. Drug repurposing is a strategy for identifying new medical use for approved drugs. A drug screening campaign showed that the ß2-adrenergic receptor (ß2-AR) agonists clenbuterol hydrochloride (CLEN) and salmeterol xinafoate (SALM) increase the proliferation rate of neural progenitor cells from the Ts65Dn model of DS. The goal of the current study was to establish their efficacy in vivo, in the Ts65Dn model. We found that, at variance with the in vitro experiments, treatment with CLEN or SALM did not restore neurogenesis in the hippocampus of Ts65Dn mice treated during the postnatal (P) period P3-P15. In Ts65Dn mice treated with CLEN or SALM, however, dendritic spine density and dendritic arborization of the hippocampal granule cells were restored and the lowest dose tested here (0.01 mg/kg/day) was sufficient to elicit these effects. CLEN and SALM are used in children as therapy for asthma and, importantly, they pass the blood-brain barrier. Our study suggests that treatment with these ß2-AR agonists may be a therapy of choice in order to correct dendritic development in DS but is not suitable to rescue neurogenesis.

Excellent long-term results with minimally invasive edge-to-edge repair in myxomatous degenerative mitral valve regurgitation.

OBJECTIVES: Previous series of minimally invasive mitral valve repairs showed excellent results at up to 10 years of follow-up. The goal of this study was to assess the long-term durability beyond 10 years of the edge-to-edge repair for myxomatous degeneration performed through a minimally invasive approach. METHODS: Ninety-seven consecutive patients (mean age 35 ± 9 years; left ventricular ejection fraction 63 ± 6%) with severe myxomatous mitral regurgitation (MR) underwent mitral valve repair through a right minithoracotomy between 1999 and 2006. MR was due to lesions involving the posterior leaflet (7.2% of patients), anterior leaflet (12.4%) and both leaflets (80.4%). RESULTS: No hospital deaths occurred. At hospital discharge all patients had no or trivial MR. Follow-up was 100% complete (median 15.5 years; interquartile range 13.6-17.0, max 19.3 years). The 16-year overall survival rate was 95.9 ± 2.02% [95% confidence interval (CI) 89.39-98.43]. At 16 years, the cumulative incidence function of cardiac death, with non-cardiac death as a competing risk, was 3.1 ± 1.75 (95% CI 0.83-8.02). Only 3 patients (4.1%) had redo operations for recurrent severe MR. At 16 years, the cumulative incidence functions of reoperation for and recurrence of MR ≥3+, with death as a competing risk, were 3.1 ± 1.76% (95% CI 0.83-8.02) and 5.6 ± 2.47% (95% CI 2.06-11.83), respectively. No predictors of recurrence of MR ≥3+ were identified. At the last follow-up, moderate MR (2+/4+) was detected in 17 patients (17.5%); most of the patients were in New York Heart Association functional class I-II (97%) and in sinus rhythm (90%). CONCLUSIONS: Minimally invasive mitral valve edge-to-edge repair through a right minithoracotomy for myxomatous degeneration appears to be an effective and durable approach even in the long-term follow-up (up to 19 years).

Timing of Treatment with the Flavonoid 7,8-DHF Critically Impacts on Its Effects on Learning and Memory in the Ts65Dn Mouse.

No therapies currently exist for intellectual disability in Down syndrome (DS). In view of its similarities with DS, including learning and memory (L&M) defects, the Ts65Dn mouse model of DS is widely used for the design of therapy. 7,8-dihydroxyflavone (7,8-DHF), a flavonoid that targets the tropomyosin-related kinase B (TrkB) receptor of brain-derived neurotrophic factor (BDNF), exerts positive effects in various brain disease models. Based on previous demonstration that administration of 7,8-DHF in the postnatal period P3-P15 restores hippocampal neurogenesis and spinogenesis, we sought to establish whether these effects translate into behavioral benefits after treatment cessation. We found that Ts65Dn mice treated with 7,8-DHF (5.0 mg/kg/day) during postnatal days P3-P15 did not show any L&M improvement at one month after treatment cessation, indicating that the effects of 7,8-DHF on the brain are ephemeral. Based on evidence that chronic treatment with 7,8-DHF in juvenile Ts65Dn mice restores L&M, we sought to establish whether a similar effect is elicited in adulthood. We found that Ts65Dn mice treated with 7,8-DHF (5.0 mg/kg/day) for about 40 days starting from 4 months of age did not show any improvement in L&M. The results suggest that timing of therapy with 7,8-DHF is a critical issue for attainment of positive effects on the brain.

Neonatal treatment with cyclosporine A restores neurogenesis and spinogenesis in the Ts65Dn model of Down syndrome.

Down syndrome (DS), a genetic condition due to triplication of chromosome 21, is characterized by reduced proliferation of neural progenitor cells (NPCs) starting from early life stages. This defect is worsened by a reduction of neuronogenesis (accompanied by an increase in astrogliogenesis) and dendritic spine atrophy. Since this triad of defects underlies intellectual disability, it seems important to establish whether it is possible to pharmacologically correct these alterations. In this study, we exploited the Ts65Dn mouse model of DS in order to obtain an answer to this question. In the framework of an in vitro drug-screening campaign of FDA/EMA-approved drugs, we found that the immunosuppressant cyclosporine A (CSA) restored proliferation, acquisition of a neuronal phenotype, and maturation of neural progenitor cells (NPCs) from the subventricular zone (SVZ) of the lateral ventricle of Ts65Dn mice. Based on these findings, we treated Ts65Dn mice with CSA in the postnatal period P3-P15. We found that treatment fully restored NPC proliferation in the SVZ and in the subgranular zone of the hippocampal dentate gyrus, and total number of hippocampal granule cells. Moreover, CSA enhanced development of dendritic spines on the dendritic arbor of the granule cells whose density even surpassed that of euploid mice. In hippocampal homogenates from Ts65Dn mice, we found that CSA normalized the excessive levels of p21, a key determinant of proliferation impairment. Results show that neonatal treatment with CSA restores the whole triad of defects of the trisomic brain. In DS CSA treatment may pose caveats because it is an immunosuppressant that may cause adverse effects. However, CSA analogues that mimic its effect without eliciting immunosuppression may represent practicable tools for ameliorating brain development in individuals with DS.

Subicular hypotrophy in fetuses with Down syndrome and in the Ts65Dn model of Down syndrome.

Intellectual disability in Down syndrome (DS) has been attributed to neurogenesis impairment during fetal brain development. Consistently with explicit memory alterations observed in children with DS, fetuses with DS exhibit neurogenesis impairment in the hippocampus, a key region involved in memory formation and consolidation. Recent evidence suggests that the subiculum plays a unique role in memory retrieval, a process that is also altered in DS. While much attention has been devoted to the hippocampus, there is a striking lack of information regarding the subiculum of individuals with DS and DS models. In order to fill this gap, in the current study, we examined the subiculum of fetuses with DS and of the Ts65Dn mouse model of DS. We found that in fetuses with DS (gestational week: 17-21), the subiculum had a reduced thickness, a reduced cell density, a reduced density of progenitor cells in the ventricular zone, a reduced percentage of neurons, and an increased percentage of astrocytes and of cells immunopositive for calretinin-a protein expressed by inhibitory interneurons. Similarly to fetuses with DS, the subiculum of neonate Ts65Dn mice was reduced in size, had a reduced number of neurons and a reduced number of proliferating cells. Results suggest that the developmental defects in the subiculum of fetuses with DS may underlie impairment in recall memory and possibly other functions played by the subiculum. The finding that the subiculum of the Ts65Dn mouse exhibits neuroanatomical defects resembling those seen in fetuses with DS further validates the use of this model for preclinical studies.

Treatment with corn oil improves neurogenesis and cognitive performance in the Ts65Dn mouse model of Down syndrome.

Individuals with Down syndrome (DS), a genetic condition due to triplication of Chromosome 21, are characterized by intellectual disability that worsens with age. Since impairment of neurogenesis and dendritic maturation are very likely key determinants of intellectual disability in DS, interventions targeted to these defects may translate into a behavioral benefit. While most of the neurogenesis enhancers tested so far in DS mouse models may pose some caveats due to possible side effects, substances naturally present in the human diet may be regarded as therapeutic tools with a high translational impact. Linoleic acid and oleic acid are major constituents of corn oil that positively affect neurogenesis and neuron maturation. Based on these premises, the goal of the current study was to establish whether treatment with corn oil improves hippocampal neurogenesis and hippocampus-dependent memory in the Ts65Dn model of DS. Four-month-old Ts65Dn and euploid mice were treated with saline or corn oil for 30 days. Evaluation of behavior at the end of treatment showed that Ts65Dn mice treated with corn oil underwent a large improvement in hippocampus-dependent learning and memory. Evaluation of neurogenesis and dendritogenesis showed that in treated Ts65Dn mice the number of new granule cells of the hippocampal dentate gyrus and their dendritic pattern became similar to those of euploid mice. In addition, treated Ts65Dn mice underwent an increase in body and brain weight. This study shows for the first time that fatty acids have a positive impact on the brain of the Ts65Dn mouse model of DS. These results suggest that a diet that is rich in fatty acids may exert beneficial effects on cognitive performance in individuals with DS without causing adverse effects.

Abnormal development of the inferior temporal region in fetuses with Down syndrome.

Down syndrome (DS) is a genetic condition associated with impairment in several cognitive domains. Previous evidence showed a notable neurogenesis reduction in the hippocampal region of DS fetuses, which may account for the impairment of declarative memory that characterizes DS starting from early life stages. The fusiform gyrus (FG) and the inferior temporal gyrus (ITG) play a key role in visual recognition memory, a function that is impaired in children and adults with DS. The goal of the current study was to establish whether fetuses with DS (17-21 weeks of gestation) exhibit neuroanatomical alterations in the FG and ITG that may underlie recognition memory impairment. We found that the FG and ITG of fetuses with DS had a reduced thickness and fewer cells in comparison with euploid fetuses. Moreover, DS fetuses had fewer cells expressing the neuronal marker NeuN than euploid fetuses, but a similar number of cells expressing the astrocytic marker GFAP and, consequently, a higher percentage of astrocytes. Immunohistochemistry for calretinin (CR), a marker of GABAergic interneurons, showed that in DS fetuses the ratio of CR-positive vs. CR-negative cells was greater than in euploid fetuses, both in the FG (177%) and ITG (161%). An increased ratio of CR-positive vs. CR-negative cells was also found in the entorhinal cortex, hippocampus and dentate gyrus. Results provide novel evidence that the FG and ITG of DS fetuses exhibit numerous developmental defects. These defects may underlie the functional alterations in visual recognition memory observed in children with DS.

Second cross-clamping after mitral valve repair for degenerative disease in contemporary practice.

OBJECTIVES: Scanty data are available on 'second cross-clamping' following mitral valve repair in contemporary practice. The aim of this study was to evaluate the incidence, causes and outcomes of this event in patients referred for mitral repair for severe degenerative mitral regurgitation (MR). METHODS: The study population included 2318 patients with severe degenerative MR referred for mitral repair. A second cross-clamping was performed in 94 (4%) patients. Causes of the second cross-clamping, revising repair procedures, immediate echocardiographic outcomes and postoperative course were assessed and compared with the 'single cross-clamping cases' (2224 patients used as control). Clinical and echocardiographic follow-up information was available for 91 of the 94 second cross-clamping patients (97% complete) (median time 6 years, interquartile range 3-11). RESULTS: The most frequent causes of the second cross-clamping were residual MR >1+/4+ and systolic anterior motion. A residual prolapse was identified in 41 (43.5%) patients, systolic anterior motion in 22 (23.5%), untreated clefts in 14 (15%) and other mechanisms in 17 (18%). Second cardiopulmonary bypass and aortic cross-clamping times were 36 (range 28-50) and 23 (range 17-34) min, respectively. Hospital mortality was 0% in the second cross-clamping and 0.3% in the control group (P = 0.2). Postoperative complications and length of hospital stay were similar. At discharge, residual MR ≥2+/4+ was 2.1% in the second cross-clamping and 2.7% in the control group (P = 0.99). In the second cross-clamping, at 12 years, the cumulative incidence function of reoperation, recurrent MR ≥3+ and MR ≥2+ with death as competing risk were 5.7 ± 2.5% (95% confidence interval 2-12), 10.3 ± 4.3% (95% confidence interval 3.8-20) and 17 ± 5.2% (95% confidence interval 8-29), respectively. CONCLUSIONS: In a large volume centre for mitral repair, a second cross-clamping is still performed in 3-5% of the patients. Because suboptimal immediate results are associated with impaired late outcomes of mitral reconstruction, a low threshold for a second cross-clamping seems to be justified. If the second repair is carried out with a relatively shorter additional cross-clamping time, mortality and morbidity are not increased and immediate and long-term results are very satisfactory.

Neurogenesis impairment: An early developmental defect in Down syndrome.

Down syndrome (DS) is characterized by brain hypotrophy and intellectual disability starting from early life stages. Accumulating evidence shows that the phenotypic features of the DS brain can be traced back to the fetal period since the DS brain exhibits proliferation potency reduction starting from the critical time window of fetal neurogenesis. This defect is worsened by the fact that neural progenitor cells exhibit reduced acquisition of a neuronal phenotype and an increase in the acquisition of an astrocytic phenotype. Consequently, the DS brain has fewer neurons in comparison with the typical brain. Although apoptotic cell death may be increased in DS, this does not seem to be the major cause of brain hypocellularity. Evidence obtained in brains of individuals with DS, DS-derived induced pluripotent stem cells (iPSCs), and DS mouse models has provided some insight into the mechanisms underlying the developmental defects due to the trisomic condition. Although many triplicated genes may be involved, in the light of the studies reviewed here, DYRK1A, APP, RCAN1 and OLIG1/2 appear to be particularly important determinants of many neurodevelopmental alterations that characterize DS because their triplication affects both the proliferation and fate of neural precursor cells as well as apoptotic cell death. Based on the evidence reviewed here, pathways downstream to these genes may represent strategic targets, for the design of possible interventions.

A flavonoid agonist of the TrkB receptor for BDNF improves hippocampal neurogenesis and hippocampus-dependent memory in the Ts65Dn mouse model of DS.

Intellectual disability is the unavoidable hallmark of Down syndrome (DS), with a heavy impact on public health. Reduced neurogenesis and impaired neuron maturation are considered major determinants of altered brain function in DS. Since the DS brain starts at a disadvantage, attempts to rescue neurogenesis and neuron maturation should take place as soon as possible. The brain-derived neurotrophic factor (BDNF) is a neurotrophin that plays a key role in brain development by specifically binding to tropomyosin-related kinase receptor B (TrkB). Systemic BDNF administration is impracticable because BDNF has a poor blood-brain barrier penetration. Recent screening of a chemical library has identified a flavone derivative, 7,8-dihydroxyflavone (7,8-DHF), a small-molecule that crosses the blood-brain barrier and binds with high affinity and specificity to the TrkB receptor. The therapeutic potential of TrkB agonists for neurogenesis improvement in DS has never been examined. The goal of our study was to establish whether it is possible to restore brain development in the Ts65Dn mouse model of DS by targeting the TrkB receptor with 7,8-DHF. Ts65Dn mice subcutaneously injected with 7,8-DHF in the neonatal period P3-P15 exhibited a large increase in the number of neural precursor cells in the dentate gyrus and restoration of granule cell number, density of dendritic spines and levels of the presynaptic protein synaptophysin. In order to establish the functional outcome of treatment, mice were treated with 7,8-DHF from P3 to adolescence (P45-50) and were tested with the Morris Water Maze. Treated Ts65Dn mice exhibited improvement of learning and memory, indicating that the recovery of the hippocampal anatomy translated into a functional rescue. Our study in a mouse model of DS provides novel evidence that treatment with 7,8-DHF during the early postnatal period restores the major trisomy-linked neurodevelopmental defects, suggesting that therapy with 7,8-DHF may represent a possible breakthrough for Down syndrome.

Neuroanatomical alterations and synaptic plasticity impairment in the perirhinal cortex of the Ts65Dn mouse model of Down syndrome.

Down syndrome (DS), a genetic condition due to triplication of Chromosome 21, is characterized by numerous neurodevelopmental alterations and intellectual disability. Individuals with DS and DS mouse models are impaired in several memory domains, including hippocampus-dependent declarative (spatial, in rodents) memory and visual recognition memory, a form of memory in which the perirhinal cortex (PRC) plays a fundamental role. The anatomo-functional substrates of hippocampus-dependent memory impairment have been largely elucidated in the Ts65Dn mouse model of DS. In contrast, there is a lack of corresponding information regarding visual recognition memory. Therefore, we deemed it of interest to examine at both an anatomical and functional level the PRC of Ts65Dn mice. We found that the PRC of adult (1.5-3.5month-old) Ts65Dn mice exhibited diffused hypocellularity and neurons with a reduced spine density. No difference between Ts65Dn and euploid mice was detected in the abundance of glutamatergic and GABAergic terminals. We examined brain slices for long-term potentiation (LTP), a form of synaptic plasticity involved in long-term memory. Theta burst stimulation of intracortical fibers was used in order to elicit LTP in the superficial layers of the PRC. We found that in trisomic slices LTP had a similar time-course but a reduced magnitude in comparison with euploid slices. While exposure to the GABAA receptor antagonist picrotoxin had no effect on LTP magnitude, exposure to the GABAB receptor antagonist CGP55845 caused an increase in LTP magnitude that became even larger than in euploid slices. Western blot analysis showed increased levels of the G-protein-activated inwardly rectifying K+ channel 2 (GIRK2) in the PRC of Ts65Dn mice, consistent with triplication of the gene coding for GIRK2. This suggests that the reduced magnitude of LTP may be caused by GIRK2-dependent exaggerated GABAB receptor-mediated inhibition. Results provide novel evidence for anatomo-functional alterations in the PRC of Ts65Dn mice. These alterations may underlie trisomy-due impairment in visual recognition memory.

Minimally invasive or conventional edge-to-edge repair for severe mitral regurgitation due to bileaflet prolapse in Barlow's disease: does the surgical approach have an impact on the long-term results?

OBJECTIVES: To evaluate whether the adoption of a right minithoracotomy operative approach had an impact on the long-term results of edge-to-edge (EE) repair compared to conventional sternotomy in patients with Barlow's disease and bileaflet prolapse. METHODS: We assessed the long-term results of 104 patients with Barlow's disease treated with a minimally invasive EE technique. An equal number of patients had a conventional median sternotomy EE repair for the same disease and were used as a control group. The inverse probability of treatment weighting was used to create comparable distributions of the covariates that were significantly different at baseline in the two groups. We performed a comparative analysis of the groups. RESULTS: No hospital deaths were observed. Follow-up was 99.5% complete (median 11.3 years). The cumulative incidence function (CIF) of cardiac death at 12 years, with noncardiac death as a competing risk, showed no difference between the two groups ( P = 0.87). At 12 years, the CIF of recurrent MR ≥ 3+, with death as the competing risk, was 7% in the sternotomy group and 5% in the minimally invasive group ( P = 0.30), and the CIF of recurrence of MR ≥ 2+ was 15 and 14%, respectively ( P = 0.63). The type of surgical approach was not a predictor of cardiac death, reoperation, recurrent MR ≥ 3+ or recurrent MR ≥ 2+. CONCLUSIONS: A minimally invasive approach does not have a negative impact on the effectiveness and long-term durability of the EE repair for bileaflet prolapse in Barlow's disease. Long-term outcomes are excellent, and valvular performance remains stable over time with no evidence of mitral stenosis.

Long-term effect of neonatal inhibition of APP gamma-secretase on hippocampal development in the Ts65Dn mouse model of Down syndrome.

Neurogenesis impairment is considered a major determinant of the intellectual disability that characterizes Down syndrome (DS), a genetic condition caused by triplication of chromosome 21. Previous evidence obtained in the Ts65Dn mouse model of DS showed that the triplicated gene APP (amyloid precursor protein) is critically involved in neurogenesis alterations. In particular, excessive levels of AICD (amyloid precursor protein intracellular domain) resulting from APP cleavage by gamma-secretase increase the transcription of Ptch1, a Sonic Hedgehog (Shh) receptor that keeps the mitogenic Shh pathway repressed. Previous evidence showed that neonatal treatment with ELND006, an inhibitor of gamma-secretase, reinstates the Shh pathway and fully restores neurogenesis in Ts65Dn pups. In the framework of potential therapies for DS, it is extremely important to establish whether the positive effects of early intervention are retained after treatment cessation. Therefore, the goal of the current study was to establish whether early treatment with ELND006 leaves an enduring trace in the brain of Ts65Dn mice. Ts65Dn and euploid pups were treated with ELND006 in the postnatal period P3-P15 and the outcome of treatment was examined at ~one month after treatment cessation. We found that in treated Ts65Dn mice the pool of proliferating cells in the hippocampal dentate gyrus (DG) and total number of granule neurons were still restored as was the number of pre- and postsynaptic terminals in the stratum lucidum of CA3, the site of termination of the mossy fibers from the DG. Accordingly, patch-clamp recording from field CA3 showed functional normalization of the input to CA3. Unlike in field CA3, the number of pre- and postsynaptic terminals in the DG of treated Ts65Dn mice was no longer fully restored. The finding that many of the positive effects of neonatal treatment were retained after treatment cessation provides proof of principle demonstration of the efficacy of early inhibition of gamma-secretase for the improvement of brain development in DS.

Can Perceval sutureless valve reduce the rate of patient-prosthesis mismatch?†.

OBJECTIVES: The aim of this study is to compare the theoretical incidence of patient-prosthesis mismatch (PPM) in patients undergoing a sutureless or a sutured aortic valve replacement using an exact statistical matching. METHODS: Between May 2012 and March 2016, 65 patients with severe symptomatic aortic stenosis underwent a sutureless aortic valve replacement with the Perceval bioprosthesis in 2 centres. Moreover, 177 aortic valve replacements with conventional sutured bioprosthesis were performed between August 2003 and September 2015. Perceval and sutured patients were 1:1 exactly matched for sex and body surface area (BSA), resulting in 62 couples (sutureless: BSA 1.77 ± 0.16 m 2 , female 62.9% vs sutured: BSA 1.77 ± 0.15 m 2 , female 62.9%). RESULTS: After matching, the indexed effective orifice area was 1.50 ± 0.18 cm 2 /m 2 and 0.81 ± 0.19 cm 2 /m 2 in the sutureless and the sutured group, respectively ( P < 0.001). No PPM occurred in patients who received a Perceval bioprosthesis ( n = 62). In the sutured group ( n = 62), 38 patients (61.3%) developed a PPM, which was moderate in 41.9% ( n = 26) and severe in 19.4% ( n = 12) ( P < 0.001). CONCLUSIONS: The indexed effective orifice area of the sutureless group was significantly larger than in the sutured one. The incidence of PPM with the conventional sutured biprosthesis was 61.3%, while it decreases to 0% in the sutureless group. No PPM was reported in the sutureless valve group. Therefore, the Perceval sutureless valve provides larger effective orifice areas compared to the sutured conventional bioprosthesis and could be considered as a good option to reduce the risk of a PPM.