Association of serotonin receptor gene polymorphisms with anorexia nervosa: a systematic review and meta-analysis.

PURPOSE: Several studies have investigated the association between anorexia nervosa and polymorphisms of genes regulating serotonin neurotransmission, with a focus on the rs6311 polymorphism of 5-HTR2A. However, inconsistent results of these studies and conflicting conclusions of existing meta-analyses complicate the understanding of a possible association. We have updated these results and evaluated the involvement of other serotonin receptor gene polymorphisms in anorexia nervosa. METHODS: Adhering to PRISMA guidelines, we have searched studies on anorexia nervosa and serotonin-regulating genes published from 1997 to 2022, selected those concerning receptor genes and meta-analyzed the results from twenty candidate gene studies on the 5-HTR2A rs6311 polymorphism and the 5-HTR2C rs6318 polymorphism. RESULTS: Present analyses reveal an association for the 5-HTR2A rs6311 polymorphism, with G and A alleles, across eighteen studies (2049 patients, 2877 controls; A vs. G allele, Odds Ratio = 1.24; 95% Confidence Interval = 1.06-1.47; p = 0.009). However, after geographic subgrouping, an association emerged only in a Southern European area, involving five studies (722 patients, 773 controls; A vs. G allele, Odds Ratio = 1.82; 95% Confidence Interval = 1.41-2.37; p < 0.00001). No association was observed for the 5-HTR2C rs6318 polymorphism across three studies. CONCLUSIONS: To date, the involvement in the pathophysiology of anorexia nervosa of the 5-HTR2A rs6311 polymorphism appears limited to a specific genetic and/or environmental context, while that of the 5-HTR2C rs6318 polymorphism seems excluded. Genome-wide association studies and epigenetic studies will likely offer deeper insights of genetic and environmental factors possibly contributing to the disorder. LEVEL OF EVIDENCE: III Evidence obtained from well-designed cohort or case-control analytic studies. Clinical trial registration PROSPERO registration number: CRD42021246122.

Oxytocin administration in neonates shapes hippocampal circuitry and restores social behavior in a mouse model of autism.

Oxytocin is an important regulator of the social brain. In some animal models of autism, notably in Magel2tm1.1Mus-deficient mice, peripheral administration of oxytocin in infancy improves social behaviors until adulthood. However, neither the mechanisms responsible for social deficits nor the mechanisms by which such oxytocin administration has long-term effects are known. Here, we aimed to clarify these oxytocin-dependent mechanisms, focusing on social memory performance. Using in situ hybridization (RNAscope), we have established that Magel2 and oxytocin receptor are co-expressed in the dentate gyrus and CA2/CA3 hippocampal regions involved in the circuitry underlying social memory. Then, we have shown that Magel2tm1.1Mus-deficient mice, evaluated in a three-chamber test, present a deficit in social memory. Next, in hippocampus, we conducted neuroanatomical and functional studies using immunostaining, oxytocin-binding experiments, ex vivo electrophysiological recordings, calcium imaging and biochemical studies. We demonstrated: an increase of the GABAergic activity of CA3-pyramidal cells associated with an increase in the quantity of oxytocin receptors and of somatostatin interneurons in both DG and CA2/CA3 regions. We also revealed a delay in the GABAergic development sequence in Magel2tm1.1Mus-deficient pups, linked to phosphorylation modifications of KCC2. Above all, we demonstrated the positive effects of subcutaneous administration of oxytocin in the mutant neonates, restoring hippocampal alterations and social memory at adulthood. Although clinical trials are debated, this study highlights the mechanisms by which peripheral oxytocin administration in neonates impacts the brain and demonstrates the therapeutic value of oxytocin to treat infants with autism spectrum disorders.

Brugada syndrome genetics is associated with phenotype severity.

AIMS: Brugada syndrome (BrS) is associated with an increased risk of sudden cardiac death due to ventricular tachycardia/fibrillation (VT/VF) in young, otherwise healthy individuals. Despite SCN5A being the most commonly known mutated gene to date, the genotype-phenotype relationship is poorly understood and remains uncertain. This study aimed to elucidate the genotype-phenotype correlation in BrS. METHODS AND RESULTS: Brugada syndrome probands deemed at high risk of future arrhythmic events underwent genetic testing and phenotype characterization by the means of epicardial arrhythmogenic substrate (AS) mapping, and were divided into two groups according to the presence or absence of SCN5A mutation. Two-hundred probands (160 males, 80%; mean age 42.6 ± 12.2 years) were included in this study. Patients harbouring SCN5A mutations exhibited a spontaneous type 1 pattern and experienced aborted cardiac arrest or spontaneous VT/VF more frequently than the other subjects. SCN5A-positive patients exhibited a larger epicardial AS area, more prolonged electrograms and more frequently observed non-invasive late potentials. The presence of an SCN5A mutation explained >26% of the variation in the epicardial AS area and was the strongest predictor of a large epicardial area. CONCLUSION: In BrS, the genetic background is the main determinant for the extent of the electrophysiological abnormalities. SCN5A mutation carriers exhibit more pronounced epicardial electrical abnormalities and a more aggressive clinical presentation. These results contribute to the understanding of the genetic determinants of the BrS phenotypic expression and provide possible explanations for the varying degrees of disease expression.

First-in-man fully leadless transvenous CRT-P with a transseptal implant of WISE-CRT® system and Micra® PM.

We describe the world's first fully leadless cardiac resynchronization therapy pacing implant with transseptal approach, in a patient with pacemaker dependency, atrial fibrillation, ischemic hypokinetic cardiomyopathy, and a history of pocket infections. After lead extraction, we implanted a MicraTranscathether Pacing System® (Medtronic, Minneapolis, MN, USA) as the sole right ventricular pacemaker, and the WISECRT system (EBR Systems, Sunnyvale, CA, USA) to provide biventricular pacing. We performed the WISECRT implant procedure using the transseptal approach given the presence of a prosthetic aortic mechanical valve, achieving satisfactory periprocedural results.

Oxytocin receptors in the Magel2 mouse model of autism: Specific region, age, sex and oxytocin treatment effects.

The neurohormone oxytocin (OXT) has been implicated in the regulation of social behavior and is intensively investigated as a potential therapeutic treatment in neurodevelopmental disorders characterized by social deficits. In the Magel2-knockout (KO) mouse, a model of Schaaf-Yang Syndrome, an early postnatal administration of OXT rescued autistic-like behavior and cognition at adulthood, making this model relevant for understanding the actions of OXT in (re)programming postnatal brain development. The oxytocin receptor (OXTR), the main brain target of OXT, was dysregulated in the hippocampus of Magel2-KO adult males, and normalized upon OXT treatment at birth. Here we have analyzed male and female Magel2-KO brains at postnatal day 8 (P8) and at postnatal day 90 (P90), investigating age, genotype and OXT treatment effects on OXTR levels in several regions of the brain. We found that, at P8, male and female Magel2-KOs displayed a widespread, substantial, down-regulation of OXTR levels compared to wild type (WT) animals. Most intriguingly, the postnatal OXT treatment did not affect Magel2-KO OXTR levels at P8 and, consistently, did not rescue the ultrasonic vocalization deficits observed at this age. On the contrary, the postnatal OXT treatment reduced OXTR levels at P90 in male Magel2-KO in a region-specific way, restoring normal OXTR levels in regions where the Magel2-KO OXTR was upregulated (central amygdala, hippocampus and piriform cortex). Interestingly, Magel2-KO females, previously shown to lack the social deficits observed in Magel2-KO males, were characterized by a different trend in receptor expression compared to males; as a result, the dimorphic expression of OXTR observed in WT animals, with higher OXTR expression observed in females, was abolished in Magel2-KO mice. In conclusion, our data indicate that in Magel2-KO mice, OXTRs undergo region-specific modifications related to age, sex and postnatal OXT treatment. These results are instrumental to design precisely-timed OXT-based therapeutic strategies that, by acting at specific brain regions, could modify the outcome of social deficits in Schaaf-Yang Syndrome patients.

cSSMD: assessing collective activity for addressing off-target effects in genome-scale RNA interference screens.

MOTIVATION: Off-target activity commonly exists in RNA interference (RNAi) screens and often generates false positives. Existing analytic methods for addressing the off-target effects are demonstrably inadequate in RNAi confirmatory screens. RESULTS: Here, we present an analytic method assessing the collective activity of multiple short interfering RNAs (siRNAs) targeting a gene. Using this method, we can not only reduce the impact of off-target activities, but also evaluate the specific effect of an siRNA, thus providing information about potential off-target effects. Using in-house RNAi screens, we demonstrate that our method obtains more reasonable and sensible results than current methods such as the redundant siRNA activity (RSA) method, the RNAi gene enrichment ranking (RIGER) method, the frequency approach and the t-test. CONTACT: xiaohua_zhang@merck.com SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Inhibition of calcineurin-mediated endocytosis and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors prevents amyloid beta oligomer-induced synaptic disruption.

Synaptic degeneration, including impairment of synaptic plasticity and loss of synapses, is an important feature of Alzheimer disease pathogenesis. Increasing evidence suggests that these degenerative synaptic changes are associated with an accumulation of soluble oligomeric assemblies of amyloid beta (Abeta) known as ADDLs. In primary hippocampal cultures ADDLs bind to a subpopulation of neurons. However the molecular basis of this cell type-selective interaction is not understood. Here, using siRNA screening technology, we identified alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor subunits and calcineurin as candidate genes potentially involved in ADDL-neuron interactions. Immunocolocalization experiments confirmed that ADDL binding occurs in dendritic spines that express surface AMPA receptors, particularly the calcium-impermeable type II AMPA receptor subunit (GluR2). Pharmacological removal of the surface AMPA receptors or inhibition of AMPA receptors with antagonists reduces ADDL binding. Furthermore, using co-immunoprecipitation and photoreactive amino acid cross-linking, we found that ADDLs interact preferentially with GluR2-containing complexes. We demonstrate that calcineurin mediates an endocytotic process that is responsible for the rapid internalization of bound ADDLs along with surface AMPA receptor subunits, which then both colocalize with cpg2, a molecule localized specifically at the postsynaptic endocytic zone of excitatory synapses that plays an important role in activity-dependent glutamate receptor endocytosis. Both AMPA receptor and calcineurin inhibitors prevent oligomer-induced surface AMPAR and spine loss. These results support a model of disease pathogenesis in which Abeta oligomers interact selectively with neurotransmission pathways at excitatory synapses, resulting in synaptic loss via facilitated endocytosis. Validation of this model in human disease would identify therapeutic targets for Alzheimer disease.

Assessing QT interval in COVID-19 patients:safety of hydroxychloroquine-azithromycin combination regimen.

BACKGROUND: Hydroxychloroquine (HCQ) and azithromycin (AZT) have been proposed for COVID-19 treatment. Data available in the literature reported a potential increased risk of fatal arrhythmias under these therapies. The aim of this study was to assess the effects of these drugs on QT interval and outcome in a COVID-19 population. METHOD: A total of 112 consecutive COVID-19 patients were included in this analysis and were divided in 3 groups according to the receiving therapeutic regimens: 19 (17%) patients in Group 1 (no treatment), 40 (36%) in Group 2 (HCQ only), 53 (47%) in Group 3 (HCQ/AZT). RESULTS: A prolonged QTc interval was found in 61% of patients treated with HCQ alone or in combination with AZT, but only 4 (4%) patients showed a QTc > 500 ms. HCQ/AZT combination determined a greater increase of QTc duration compared to the other two strategies (Group 3 452 ± 26.4 vs Group 2 436.3 ± 28.4 vs Group 1 424.4 ± 24.3 ms, respectively; p < 0.001). Multivariate analysis demonstrated that HCQ/AZT combination (OR 9.02, p = 0.001) and older age (OR 1.04, p = 0.031) were independent predictors of QTc prolongation. The risk increased with age (incremental utility analysis p = 0.02). Twenty patients (18%) died, and no cardiac arrest neither arrhythmic fatalities were documented. CONCLUSIONS: The HCQ/AZT combination therapy causes a significantly increase of QT interval compared to HCQ alone. Older patients under such regimen are at higher risk of experiencing QT prolongation. The use of such drugs may be considered as safe relating to arrhythmic risk in the treatment of COVID-19 patients as no arrhythmic fatalities occurred.

Development of a novel GLUT4 translocation assay for identifying potential novel therapeutic targets for insulin sensitization.

GLUT4 (glucose transporter 4) plays important roles in glucose homoeostasis in vivo. GLUT4 expression and function are diminished in diabetic human and animal subjects. The goal of the present study is to develop a cell-based assay for identifying negative regulators of GLUT4 translocation as potential targets for the treatment of Type 2 diabetes. Traditional GLUT4 translocation assays performed in differentiated myocytes or adipocytes are difficult to perform, particularly in HTS (high-throughput screening) mode. In the present study, we stably co-expressed c-Myc and eGFP [enhanced GFP (green fluorescent protein)] dual-tagged recombinant GLUT4 with recombinant IRS1 (insulin receptor substrate 1) in HEK-293 cells (human embryonic kidney cells) (HEK-293.IRS1.GLUT4 cells). Insulin treatment stimulated both glucose uptake and GLUT4 translocation in these cells. GLUT4 translocation is quantified by a TRF (time-resolved fluorescence) assay in a 96-well HTS format. TRF assays confirmed insulin-stimulated GLUT4 translocation, which can be inhibited by PI3K (phosphoinositide 3-kinase) or Akt [also called PKB (protein kinase B)] inhibitors. Treatment with palmitate increased IRS1 serine phosphorylation and reduced insulin-stimulated Akt phosphorylation and GLUT4 translocation, indicating insulin resistance. Knockdown of PTEN (phosphatase and tensin homologue deleted on chromosome 10) and PTP1B (protein tyrosine phosphatase 1B) gene expression by siRNA (small interfering RNA) treatment significantly increased GLUT4 translocation only in cells treated with palmitate but not in untreated cells. Similar results were obtained on treatment with siRNA of JNK1 (c-Jun N-terminal kinase 1), S6K1 (ribosomal protein S6 kinase, 70 kDa, polypeptide 1) and PKC(theta) (protein kinase C theta). In summary, we have established and validated a novel GLUT4 translocation assay that is optimal for identifying negative regulators of GLUT4 translocation. In combination with more physiologically relevant secondary assays in myotubes and adipocytes, this assay system can be used to identify potential novel therapeutic targets for the treatment of Type 2 diabetes.

The E3 ubiquitin ligase AIP4 mediates ubiquitination and sorting of the G protein-coupled receptor CXCR4.

Ubiquitination of the chemokine receptor CXCR4 serves as a targeting signal for lysosomal degradation, but the mechanisms mediating ubiquitination and lysosomal sorting remain poorly understood. Here we report that the Nedd4-like E3 ubiquitin ligase AIP4 mediates ubiquitination of CXCR4 at the plasma membrane, and of the ubiquitin binding protein Hrs on endosomes. CXCR4 activation promotes CXCR4 colocalization with AIP4 and Hrs within the same region of endosomes. Endosomal sorting of CXCR4 is dependent on Hrs as well as the AAA ATPase Vps4, the latter involved in regulating the ubiquitination status of both CXCR4 and Hrs. We propose a model whereby AIP4, Hrs, and Vps4 coordinate a cascade of ubiquitination and deubiquitination events that sort CXCR4 to the degradative pathway.

Identification of small-molecule modulators of mouse SVZ progenitor cell proliferation and differentiation through high-throughput screening.

Adult mouse subventricular zone (SVZ) neural stem/progenitor cells are multipotent self-renewing cells that retain the capacity to generate the major cell types of the central nervous system in vitro and in vivo. The relative ease of expanding SVZ cells in culture as neurospheres makes them an ideal model for carrying out large-scale screening to identify compounds that regulate neural progenitor cell proliferation and differentiation. The authors have developed an adenosine triphosphate-based cell proliferation assay using adult SVZ cells to identify small molecules that activate or inhibit progenitor cell proliferation. This assay was miniaturized to a 1536-well format for high-throughput screening (HTS) of >1 million small-molecule compounds, and 325 and 581 compounds were confirmed as potential inducers of SVZ cell proliferation and differentiation, respectively. A number of these compounds were identified as having a selective proliferative and differentiation effect on SVZ cells versus mouse Neuro2a neuroblastoma cells. These compounds can potentially be useful pharmacological tools to modulate resident stem cells and neurogenesis in the adult brain. This study represents a novel application of primary somatic stem cells in the HTS of a large-scale compound library.

G protein-coupled receptor/arrestin3 modulation of the endocytic machinery.

Nonvisual arrestins (arr) modulate G protein-coupled receptor (GPCR) desensitization and internalization and bind to both clathrin (CL) and AP-2 components of the endocytic coated pit (CP). This raises the possibility that endocytosis of some GPCRs may be a consequence of arr-induced de novo CP formation. To directly test this hypothesis, we examined the behavior of green fluorescent protein (GFP)-arr3 in live cells expressing beta2-adrenergic receptors and fluorescent CL. After agonist stimulation, the diffuse GFP-arr3 signal rapidly became punctate and colocalized virtually completely with preexisting CP spots, demonstrating that activated complexes accumulate in previously formed CPs rather than nucleating new CP formation. After arr3 recruitment, CP appeared larger: electron microscopy analysis revealed an increase in both CP number and in the occurrence of clustered CPs. Mutant arr3 proteins with impaired binding to CL or AP-2 displayed reduced recruitment to CPs, but were still capable of inducing CP clustering. In contrast, though constitutively present in CPs, the COOH-terminal moiety of arr3, which contains CP binding sites but lacks receptor binding, did not induce CP clustering. Together, these results indicate that recruitment of functional arr3-GPCR complexes to CP is necessary to induce clustering. Latrunculin B or 16 degrees C blocked CP rearrangements without affecting arr3 recruitment to CP. These results and earlier studies suggest that discrete CP zones exist on cell surfaces, each capable of supporting adjacent CPs, and that the cortical actin membrane skeleton is intimately involved with both the maintenance of existing CPs and the generation of new structures.

Small interfering RNA screens reveal enhanced cisplatin cytotoxicity in tumor cells having both BRCA network and TP53 disruptions.

RNA interference technology allows the systematic genetic analysis of the molecular alterations in cancer cells and how these alterations affect response to therapies. Here we used small interfering RNA (siRNA) screens to identify genes that enhance the cytotoxicity (enhancers) of established anticancer chemotherapeutics. Hits identified in drug enhancer screens of cisplatin, gemcitabine, and paclitaxel were largely unique to the drug being tested and could be linked to the drug's mechanism of action. Hits identified by screening of a genome-scale siRNA library for cisplatin enhancers in TP53-deficient HeLa cells were significantly enriched for genes with annotated functions in DNA damage repair as well as poorly characterized genes likely having novel functions in this process. We followed up on a subset of the hits from the cisplatin enhancer screen and validated a number of enhancers whose products interact with BRCA1 and/or BRCA2. TP53(+/-) matched-pair cell lines were used to determine if knockdown of BRCA1, BRCA2, or validated hits that associate with BRCA1 and BRCA2 selectively enhances cisplatin cytotoxicity in TP53-deficient cells. Silencing of BRCA1, BRCA2, or BRCA1/2-associated genes enhanced cisplatin cytotoxicity approximately 4- to 7-fold more in TP53-deficient cells than in matched TP53 wild-type cells. Thus, tumor cells having disruptions in BRCA1/2 network genes and TP53 together are more sensitive to cisplatin than cells with either disruption alone.

Five years of experience using palatal mini-implants for orthodontic anchorage.

PURPOSE: The authors review 5 years of clinical experience using Straumann Orthosystem (Straumann, Basel, Switzerland) palatal mini-implants for orthodontic anchorage, describe clinical procedures, and give statistical results. MATERIALS AND METHODS: Diagnostic planning, surgical phase, and clinical procedure are described. The diagnostic planning was performed on lateral cephalogram in 13 cases; in 1 case, with an ectopically included upper canine, a computed tomography was requested. The Straumann Orthosystem kit includes a pure titanium implant with the healing cap, and a set of burs and instruments for the surgical insertion and removal. The sample comprised 14 adult patients (2 males and 12 females) requiring fixed orthodontic appliance for Class II malocclusion. Because of critical anchorage conditions they had received a palatal mini-implant as absolute anchorage during orthodontic treatment: 9 implants of 6.0 mm and 7 implants of 4.0 mm were positioned, primarily using a 2.5 mm transmucosal neck length. The orthodontic phase always started after 13 weeks of the insertion, in order to ensure osteointegration. RESULTS: In all cases, neither a perforation of the nasal cavity nor other surgical complication occurred. All implants have been successfully osteointegrated, except for 1 which has been lost for critical hygiene conditions. Two implants needed to be replaced because of tongue forces, which had been determined to interfere with the osteointegration immediately after surgery; this inconvenience was afterwards solved by the use of a resin splint. CONCLUSIONS: Palatal mini-implants revealed to be clinically easy to use and proved to be an efficient auxiliary device in orthodontics when absolute anchorage is needed.

Sorafenib and thyroid cancer.

Sorafenib (Nexavar) is a multikinase inhibitor, which has demonstrated both anti-proliferative and anti-angiogenic properties in vitro and in vivo, inhibiting the activity of targets present in the tumor cell [c-RAF (proto-oncogene serine/threonine-protein kinase), BRAF, (V600E)BRAF, c-KIT, and FMS-like tyrosine kinase 3] and in tumor vessels (c-RAF, vascular endothelial growth factor receptor-2, vascular endothelial growth factor receptor-3, and platelet-derived growth factor receptor ß). For several years, sorafenib has been approved for the treatment of hepatocellular carcinoma and advanced renal cell carcinoma. After previous studies showing that sorafenib was able to inhibit oncogenic RET mutants, (V600E)BRAF, and angiogenesis and growth of orthotopic anaplastic thyroid cancer xenografts in nude mice, some clinical trials demonstrated the effectiveness of sorafenib in advanced thyroid cancer. Currently, the evaluation of the clinical safety and efficacy of sorafenib for the treatment of advanced thyroid cancer is ongoing. This article reviews the anti-neoplastic effect of sorafenib in thyroid cancer. Several completed (or ongoing) studies have evaluated the long-term efficacy and tolerability of sorafenib in patients with papillary and medullary aggressive thyroid cancer. The results suggest that sorafenib is a promising therapeutic option in patients with advanced thyroid cancer that is not responsive to traditional therapeutic strategies.

New targeted therapies for anaplastic thyroid cancer.

Anaplastic thyroid cancer (ATC) is often incurable because it doesn't respond to radioiodine, radiotherapy or chemotherapy, and new therapeutic approaches are needed. Peroxisome proliferator-activated receptor-gamma (PPARg) gene and protein are present in ATC cells, and PPARg ligands inhibit cell proliferation, induce apoptosis, and also down regulate the invasive potential of ATC cells. Also, inhibitors of the Aurora serine/threonine kinases have antineoplastic effect on ATC cells in vitro and on ATC xenografts. Tyrosine kinases inhibitors are actually under evaluation for the treatment of ATC, for example imanitib or sorafenib. Other studies have focused on evaluating antiangiogenic agents for treatment of ATC. These agents include: combretastatin A4 phosphate, aplidin, PTK787/ZK222584, and human VEGF monoclonal antibodies (bevacizumab, cetuximab). Small-molecule adenosine triphosphate (ATP) competitive inhibitors directed intracellularly at epidermal growth factor receptor (EGFR)'s tyrosine kinase, such as erlotinib, or gefitinib are also under evaluation. The development of drugs that have multiple therapeutic targets and the utilization of multiple cancer-targeting agents are both emerging strategies for ATC treatment. For example, a preclinical study evaluated the activity of a dual inhibitor of EGFR and vascular endothelial growth factor (VEGF), NVP-AEE788, alone and in combination with paclitaxel for the treatment of ATC. Even if new therapeutic approaches against ATC are under development, more research is needed to finally identify therapies able to control and to cure this disease. The possibility of testing the sensitivity of primary ATC cells from each subject to different drugs could increase the effectiveness of the treatment in the next future.

A multiplexed siRNA screening strategy to identify genes in the PARP pathway.

Gene silencing by RNA interference has become a powerful tool to help identify genes that regulate biological processes. However, the complexity of the biology probed and the incomplete validation of the reagents used make it difficult to interpret the results of genome-wide siRNA screens. To address this challenge and maximize the return on the efforts required for validating genomic screen hits, the screening strategy must be designed to increase the robustness of the primary screening hits and include assays that inform on the mechanism of action of the knocked-down transcripts. Here, we describe the implementation of a small interfering RNA (siRNA) screen to identify genes that sensitize the effect of poly-(ADP ribose)-polymerase (PARP) inhibitor on cell survival. In the strategy we designed for the primary screen, two biological activities, apoptosis and cell viability, were measured simultaneously at different time points in the presence and absence of a PARP inhibitor (PARPi). The multiplexed assay allowed us to identify PARPi sensitizers induced by both caspase-dependent and independent mechanisms. The multiplexed screening strategy yielded robust primary hits with significant enrichment for DNA repair genes, which were further validated using relevant high-content imaging assays and confirmation of transcript knockdown by real-time PCR (rtPCR).

Impact of prolonged cardiac unloading on left ventricular mass and longitudinal myocardial performance: an experimental bed rest study in humans.

OBJECTIVE: This study evaluated the impact of prolonged circulatory unloading and subsequent left ventricular (LV) mass decrease on LV myocardial performance. Five-week head-down tilt (-6°) bed rest (HDTBR) was used as a model of prolonged circulatory unloading. METHODS: Ten young healthy male volunteers (age 23 ± 2 years) were studied a day before and within the first 24 h after the end of HDTBR by two-dimensional Doppler echocardiography and carotid applanation tonometry. LV preload and afterload, cardiac workload, LV mass and wall stress, LV chamber function and diastolic filling were assessed. Longitudinal, radial and circumferential myocardial strain rate were evaluated by tissue tracking algorithm. RESULTS: After HDTBR, stroke volume (P < 0.01), stroke work (P = 0.01) and LV mass (P < 0.001) decreased, whereas relative wall thickness, peak and end-systolic wall stress and ejection fraction remained unchanged. HDTBR was also followed by a decrease in longitudinal systolic strain rate (-1.11 ± 0.05 vs. -1.00 ± 0.05 s, P = 0.02) and a prolongation of isovolumic relaxation time (IVRT) (74 ± 2 vs. 82 ± 3 ms, P < 0.01). Bed rest-induced changes in LV mass index were directly related to changes in stroke work index (r = 0.65, P < 0.05), and changes in longitudinal systolic strain rate and IVRT correlated with changes in stroke volume index, directly and inversely, respectively (r = 0.69 and -0.64, P < 0.05 for both). CONCLUSION: A decrease in LV mass following HDTBR parallels the reduction in cardiac workload and is associated with an attenuation of longitudinal systolic myocardial deformation rate and prolongation of IVRT that seem to reflect a functional adaptation of cardiac muscle to lower LV volume load.