Potential role of epicardial adipose tissue in coronary artery endothelial cell dysfunction in type 2 diabetes.

Cardiovascular disease is the most prevalent cause of morbidity and mortality in diabetes. Epicardial adipose tissue (EAT) lies in direct contact with the myocardium and coronary arteries and can influence cardiac (patho) physiology through paracrine signaling pathways. This study hypothesized that the proteins released from EAT represent a critical molecular link between the diabetic state and coronary artery endothelial cell dysfunction. To simulate type 2 diabetes-associated metabolic and inflammatory status in an ex vivo tissue culture model, human EAT samples were treated with a cocktail composed of high glucose, high palmitate, and lipopolysaccharide (gplEAT) and were compared with control EAT (conEAT). Compared to conEAT, gplEAT showed a markedly increased gene expression profile of proinflammatory cytokines, corroborating EAT inflammation, a hallmark feature observed in patients with type 2 diabetes. Luminex assay of EAT-secretome identified increased release of various proinflammatory cytokines, including tumor necrosis factor-alpha (TNF-alpha), interferon-alpha 2 (IFNA2), interleukin 1 beta (IL1B), interleukin 5 (IL5), interleukin 13 (IL13), and CCL5, among others, in response to high glucose, high palmitate, and lipopolysaccharide. Conditioned culture media was used to collect the concentrated proteins (CPs). In response to gplEAT-CPs, human coronary artery endothelial cells (HCAECs) exhibited an inflammatory endothelial cell phenotype, featuring a significantly increased gene expression of proinflammatory cytokines and cell surface expression of VCAM-1. Moreover, gplEAT-CPs severely decreased Akt-eNOS signaling, nitric oxide production, and angiogenic potential of HCAECs, when compared with conEAT-CPs. These findings indicate that EAT inflammation may play a key role in coronary artery endothelial cell dysfunction in type 2 diabetes.

Category similarity affects study choices in self-regulated learning.

During learning, interleaving exemplars from different categories (e.g., ABCBCACAB) rather than blocking by category (e.g., AAABBBCCC) often enhances inductive learning, especially when the categories are highly similar. However, when allowed to select their own study schedules, learners overwhelmingly tend to block rather than interleave. Category similarity has been shown to moderate the relative benefit of interleaved versus blocked study. We investigated whether learners were sensitive to category similarity when choosing exemplars for study, and whether these choices predicted their learning outcomes. In Experiment 1, learners interleaved more often when the categories were highly similar (difficult to discriminate from each other), compared with when similarity was low. In Experiment 2, learners were presented with two sets of categories to learn; categories within each set were similar to each other, but categories were dissimilar across sets. When learners chose to interleave, they tended to switch to a similar rather than dissimilar category. Importantly, learners' study choices predicted their subsequent categorization performance. Our findings suggest that learners are strategic in their search for commonalities within versus differences among categories and can regulate their study behaviors based on category similarity.

Dye-Mediated Photo-Oxidation Biomaterial Fixation: Analysis of Bioinductivity and Mechanical Properties of Bovine Pericardium for Use in Cardiac Surgery.

Extracellular matrix bioscaffolds can influence the cardiac microenvironment and modulate endogenous cellular mechanisms. These materials can optimize cardiac surgery for repair and reconstruction. We investigated the biocompatibility and bioinductivity of bovine pericardium fixed via dye-mediated photo-oxidation on human cardiac fibroblast activity. We compared a dye-mediated photo-oxidation fixed bioscaffold to glutaraldehyde-fixed and non-fixed bioscaffolds reported in contemporary literature in cardiac surgery. Human cardiac fibroblasts from consenting patients were seeded on to bioscaffold materials to assess the biocompatibility and bioinductivity. Human cardiac fibroblast gene expression, secretome, morphology and viability were studied. Dye-mediated photo-oxidation fixed acellular bovine pericardium preserves human cardiac fibroblast phenotype and viability; and potentiates a pro-vasculogenic paracrine response. Material tensile properties were compared with biomechanical testing. Dye-mediated photo-oxidation fixed acellular bovine pericardium had higher compliance compared to glutaraldehyde-fixed bioscaffold in response to tensile force. The biocompatibility, bioinductivity, and biomechanical properties of dye-mediated photo-oxidation fixed bovine pericardium demonstrate its feasibility as a bioscaffold for use in cardiac surgery. As a fixed yet bioinductive solution, this bioscaffold demonstrates enhanced compliance and retains bioinductive properties that may leverage endogenous reparative pathways. Dye-mediated photo-oxidation fixed bioscaffold warrants further investigation as a viable tool for cardiac repair and reconstruction.

Retrieval practice benefits memory precision.

Although previous research on retrieval practice (RP) has predominantly featured stimuli with discrete right-or-wrong answers, continuous measures offer potentially greater sensitivity in assessing the effects of RP on memory precision. The present study used a colour gradient (125 points ranging from magenta to yellow) as a continuous response variable. The colours of different images were learned through either RP or restudy and either one or three cycles of practice after initial study. On a delayed final test, participants' memory was assessed for each item's colour. Participants also created per-item intervals representing the region where they believed the correct colour most likely to have been. We found that repeated rounds of RP enhanced the correspondence between responses and the correct colour. In addition, RP led to participants creating more accurate (correct answers were more likely to be within the participant-specified intervals) and more precise (narrower) intervals relative to restudy, suggesting that RP enhances the precision of memories.

Influence of Wearing a Tactical Harness on Three-Dimensional Thoracic Limb Kinematics.

OBJECTIVE: The aim of this study was to assess the impact of a tactical harness on three-dimensional motion of the thoracic limb in dogs. ANIMALS: Five adult mixed-breed dogs (age: 4-6 years, weight: 25-35 kg) were used in this study. METHODS: Custom-fit tactical harnesses were applied to each dog and 19 retroreflective skin markers were used to determine three-dimensional joint motion during dynamic motion, with and without the harness. Sagittal plane (flexion-extension), transverse plane (internal-external rotation), and frontal plane (abduction-adduction) kinematics were created for the shoulder, elbow, and carpus from motion capture data, with and without the harness. Kinematic waveforms were analysed using statistical parametric mapping paired t-tests (a = 0.05). Angular displacements were determined, and total joint range of motion was compared using paired t-tests (a = 0.05). RESULTS: Wearing a tactical harness increased sagittal angular displacement in the elbow but decreased it in the shoulder and carpus. Significant differences were found in the kinematic waveforms in almost all joints at both a walk and trot. Dogs wearing the tactical harness had reduced flexion and increased abduction of the shoulder joint at a walk. The elbow joint had increased extension, reduced external rotation and increased abduction at both walk and trot. The carpus had reduced flexion at a trot and walk, as well as increased internal rotation and abduction at a walk. CONCLUSION: Wearing a tactical harness affected kinematic gait data of all joints of the forelimb. The elbow was affected in all three planes at both a walk and trot, while the shoulder joint was only affected at a walk when wearing a tactical harness. CLINICAL RELEVANCE: The clinical impact of wearing a tactical harness is unknown at this time, particularly when dogs are performing their duties while wearing harnesses.

Novel hardening bone putty enhances sternal closure and accelerates postoperative recovery.

OBJECTIVES: Regaining and maintaining sternal stability are key to recovery after cardiac surgery and resuming baseline quality of life. Montage (ABYRX) is a moldable, calcium phosphate-based putty that adheres to bleeding bone, hardens after application, and is resorbed and replaced with bone during the remodeling process. We evaluate the feasibility, safety, and efficacy of enhanced sternal closure with this novel putty to accelerate recovery in patients after sternotomy. METHODS: A single-center, single-blinded, randomized controlled trial was performed (NCT03365843). Patients undergoing elective cardiac surgery via sternotomy received sternal closure with either Montage bone putty and wire cerclage (enhanced sternal closure; n = 33) or wire cerclage alone (control; n = 27). Standardized patient-reported outcomes assessed health-related quality of life (EQ-5D Index) and physical disability (Health Assessment Questionnaire). A Likert-type 11-point scale quantified pain. Spirometry assessed respiratory function. Patients reached 6-week follow-up, with 1-year follow-up for safety end points. RESULTS: There were no device-related adverse events. Enhanced sternal closure improved physical functional recovery (reduced Healthcare Index and Quality) and quality of life (increased EQ-5D Index) at day 5/discharge, week 2, and week 4. Enhanced sternal closure reduced incisional pain while resting, breathing, sleeping, and walking at day 5/discharge. Enhanced sternal closure reduced chest wall and back pain at day 3 and day 5 discharge. A higher proportion of patients with enhanced sternal closure recovered to 60% of their baseline forced vital capacity by day 5/discharge. Enhanced sternal closure shortened hospital stay. CONCLUSIONS: Enhanced sternal closure improves and accelerates postoperative recovery compared with conventional wire closure. Earlier discharge may provide substantial cost benefits for the healthcare system.

Enhancing visuospatial learning: the benefit of retrieval practice.

Studies examining the beneficial effect of testing on memory have relied almost exclusively on verbal materials. Whether testing can improve the learning of novel, abstract visuospatial information was investigated, using Chinese characters as study stimuli. Subjects with no prior Chinese language experience studied English words paired with their Chinese equivalents. Subsequently, they either restudied the pairs twice or attempted to retrieve covertly the Chinese characters twice (with feedback provided afterward). The durations of the study and the retrieval/feedback trials were equated. On a final test given after 10 min (Experiment 1) or 24 h (Experiment 2), the subjects who had practiced retrieval were more accurate at writing/drawing the Chinese characters than were those who had studied repeatedly. The same result was replicated when learning condition was manipulated within subjects (Experiment 3). In predictions of future performance made after training, however, the subjects seemed unaware that retrieval practice was more effective than repeated studying. Testing enhances visuospatial learning, with potential implications for learning a foreign language that uses a writing script different from one's language: Repeated retrieval from memory trumps repeated studying.

Acellular bioscaffolds redirect cardiac fibroblasts and promote functional tissue repair in rodents and humans with myocardial injury.

Coronary heart disease is a leading cause of death. Tissue remodeling and fibrosis results in cardiac pump dysfunction and ischemic heart failure. Cardiac fibroblasts may rebuild damaged tissues when prompted by suitable environmental cues. Here, we use acellular biologic extracellular matrix scaffolds (bioscaffolds) to stimulate pathways of muscle repair and restore tissue function. We show that acellular bioscaffolds with bioinductive properties can redirect cardiac fibroblasts to rebuild microvascular networks and avoid tissue fibrosis. Specifically, when human cardiac fibroblasts are combined with bioactive scaffolds, gene expression is upregulated and paracrine mediators are released that promote vasculogenesis and prevent scarring. We assess these properties in rodents with myocardial infarction and observe bioscaffolds to redirect fibroblasts, reduce tissue fibrosis and prevent maladaptive structural remodeling. Our preclinical data confirms that acellular bioscaffold therapy provides an appropriate microenvironment to stimulate pathways of functional repair. We translate our observations to patients with coronary heart disease by conducting a first-in-human observational cohort study. We show that bioscaffold therapy is associated with improved perfusion of infarcted myocardium, reduced myocardial scar burden, and reverse structural remodeling. We establish that clinical use of acellular bioscaffolds is feasible and offers a new frontier to enhance surgical revascularization of ischemic heart muscle.

Direct Effects of Empagliflozin on Extracellular Matrix Remodelling in Human Cardiac Myofibroblasts: Novel Translational Clues to Explain EMPA-REG OUTCOME Results.

BACKGROUND: Empagliflozin, an SGLT2 inhibitor, has shown remarkable reductions in cardiovascular mortality and heart failure admissions (EMPA-REG OUTCOME). However, the mechanism underlying the heart failure protective effects of empagliflozin remains largely unknown. Cardiac fibroblasts play an integral role in the progression of structural cardiac remodelling and heart failure, in part, by regulating extracellular matrix (ECM) homeostasis. The objective of this study was to determine if empagliflozin has a direct effect on human cardiac myofibroblast-mediated ECM remodelling. METHODS: Cardiac fibroblasts were isolated via explant culture from human atrial tissue obtained at open heart surgery. Collagen gel contraction assay was used to assess myofibroblast activity. Cell morphology and cell-mediated ECM remodelling was examined with the use of confocal microscopy. Gene expression of profibrotic markers was assessed with the use of reverse-transcription quantitative polymerase chain reaction. RESULTS: Empagliflozin significantly attenuated transforming growth factor ß1-induced fibroblast activation via collagen gel contraction after 72-hour exposure, with escalating concentrations (0.5 µmol/L, 1 µmol/L, and 5 µmol/L) resulting in greater attenuation. Morphologic assessment showed that myofibroblasts exposed to empagliflozin were smaller in size with shorter and fewer number of extensions, indicative of a more quiescent phenotype. Moreover, empagliflozin significantly attenuated cell-mediated ECM remodelling as measured by collagen fibre alignment index. Gene expression profiling revealed significant suppression of critical profibrotic markers by empagliflozin, including COL1A1, ACTA2, CTGF, FN1, and MMP-2. CONCLUSIONS: We provide novel data showing a direct effect of empagliflozin on human cardiac myofibroblast phenotype and function by attenuation of myofibroblast activity and cell-mediated collagen remodelling. These data provide critical insights into the profound effects of empagliflozin as noted in the EMPA-REG OUTCOME study.

Pathway control in visual word processing: converging evidence from recognition memory.

The extent to which readers can exert strategic control over oral reading processes is a matter of debate. According to the pathway control hypothesis, the relative contributions of the lexical and nonlexical pathways can be modulated by the characteristics of the context stimuli being read, but an alternative time criterion model is also a viable explanation of past results. In Experiment 1, subjects named high- and low-frequency regular words in the context of either low-frequency exception words (e.g., pint) or nonwords (e.g., flirp). Frequency effects (faster pronunciation latencies for high-frequency words) were attenuated in the nonword context, consistent with the notion that nonwords emphasize the characteristics of the frequency-insensitive nonlexical pathway. Importantly, we also assessed memory for targets, and a similar attenuation of the frequency effect in recognition memory was observed in the nonword condition. Converging evidence was obtained in a second experiment in which a variable that was more sensitive to the nonlexical pathway (orthographic neighborhood size) was manipulated. The results indicated that both speeded pronunciation performance and memory performance were relatively attenuated in the low-frequency exception word context in comparision with the nonword context. The opposing influences of list context type for word frequency and orthographic neighborhood size effects in speeded pronunciation and memory performance provide strong support for the pathway control model, as opposed to the time criterion model.

Induction of human aortic myofibroblast-mediated extracellular matrix dysregulation: A potential mechanism of fluoroquinolone-associated aortopathy.

OBJECTIVES: Fluoroquinolone (FQ) antibiotics are associated with adverse aortic clinical events. We assessed human aortic myofibroblast-mediated extracellular matrix (ECM) dysregulation as a possible cellular mechanism underlying FQ-associated aortopathy. METHODS: Human aortic myofibroblasts were isolated from patients with aortopathy undergoing elective ascending aortic resection (N = 9). The capacity for extracellular matrix degradation in cells exposed to FQ was assessed by multiplex analysis of secreted matrix metalloproteinases relative to tissue inhibitors of matrix metalloproteinases (TIMPs). Direct evaluation of extracellular matrix degradation was investigated in human aortic cells using a 3-dimensional gelatin-fluorescein isothiocyanate fluorescence microgel assay. Aortic cellular collagen-1 expression following FQ exposure was determined by immunoblotting and immunofluorescent staining. Cell apoptosis, necrosis, and metabolic viability was determined by annexin-V, propidium iodide staining, and water-soluble tetrazolium salt (WST1) assay. RESULTS: FQ exposure significantly decreased aortic cell TIMP-1 (P = .004) and TIMP-2 (P = .0004) protein expression compared with vehicle control. The ratio of matrix metalloproteinase-9/TIMP-2 was increased suggesting an increased capacity for extracellular matrix degradation (P = .01). In collagen gels, we show a trend toward increased aortic myofibroblast-mediated collagen fiber degradation with FQ exposure (P = .09). Similarly, FQ exposure attenuated collagen-1 expression as assessed by immunoblotting (P = .002) and immunofluorescence (P = .02). Cell apoptosis, necrosis, and metabolic viability was not significantly influenced by FQ exposure. CONCLUSIONS: For the first time, we document a putative mechanism underlying FQ-associated aortopathy whereby decreased TIMP expression with impaired compensatory collagen-1 expression results in human aortic myofibroblast-mediated extracellular matrix dysregulation. These novel data may provide a cellular and molecular mechanism to explain the established clinical association between FQ exposure and acute aortic events.

Forward versus backward semantic priming: What movement dynamics during lexical decision reveal.

Separate processes underlying forward (e.g., crescent MOON) and backward (e.g., office POST) priming have previously been inferred from button-press lexical decision response times, with an automatic prospective mechanism and a strategic retrospective mechanism presumed responsible for forward and backward priming, respectively. We tracked hand/mouse kinematics during lexical decision, and found that forward, backward, and symmetrical (e.g., cat DOG) priming exhibited different movement trajectories, with the effect of forward priming emerging earlier than that of backward priming and with symmetrical priming taking the lead around the time when the backward priming effect came online. The findings provide strong converging evidence for different mechanisms driving forward and backward priming, and demonstrate that continuous kinematic measures can shed light on cognitive processes as they unfold in real time.

Heparin Augmentation Enhances Bioactive Properties of Acellular Extracellular Matrix Scaffold.

Extracellular matrix (ECM) maintains a reservoir of bioactive growth factors and matricellular proteins that provide bioinductive effects on local cells that influence phenotype and behaviors. Bioactive acellular ECM scaffolds can be used therapeutically to stimulate adaptive tissue repair. Fibroblast growth factor-2 (FGF-2) attenuates transforming growth factor-ß1 (TGF-ß1)-mediated cardiac fibrosis. Heparin glycosaminoglycan can influence FGF-2 bioactivity and could be leveraged to enhance tissue engineering strategies. We explored the effects of heparin on FGF-2 enhancement of bioactive ECM scaffold biomaterials for its antifibrotic effect on attenuating human cardiac myofibroblast activation. Increasing heparin concentration at a fixed concentration of FGF-2 markedly increased the amount of FGF-2 retained and eluted by ECM scaffolds. To explore synergistic bioinductive effects of heparin and FGF-2, collagen gel contraction assay using human cardiac myofibroblasts was performed in vitro. Myofibroblast activation was induced by profibrotic cytokine, TGF-ß1. FGF-2 and heparin in combination reduced human cardiac myofibroblast-mediated collagen gel contraction to a greater extent than FGF-2 alone. These observations were confirmed for both human atrial and human ventricular cardiac fibroblasts. Cell death was not different between groups. In summary, heparin is an effective adjuvant to enhance FGF-2 loading and elution of acellular ECM scaffold biomaterials. Heparin increases the bioactive effects of FGF-2 in attenuating human cardiac myofibroblast activation in response to profibrotic TGF-ß1. These data may inform tissue engineering strategies for myocardial repair to prevent fibrosis.

A Highly Proliferative Group IIC Intron from Geobacillus stearothermophilus Reveals New Features of Group II Intron Mobility and Splicing.

The thermostable Geobacillus stearothermophilus GsI-IIC intron is among the few bacterial group II introns found to proliferate to high copy number in its host genome. Here, we developed a bacterial genetic assay for retrohoming and biochemical assays for protein-dependent and self-splicing of GsI-IIC. We found that GsI-IIC, like other group IIC introns, retrohomes into sites having a 5'-exon DNA hairpin, typically from a bacterial transcription terminator, followed by short intron-binding sequences (IBSs) recognized by base pairing of exon-binding sequences (EBSs) in the intron RNA. Intron RNA insertion occurs preferentially but not exclusively into the parental lagging strand at DNA replication forks, using a nascent lagging strand DNA as a primer for reverse transcription. In vivo mobility assays, selections, and mutagenesis indicated that a variety of GC-rich DNA hairpins of 7-19 bp with continuous base pairs or internal elbow regions support efficient intron mobility and identified a critically recognized nucleotide (T-5) between the hairpin and IBS1, a feature not reported previously for group IIC introns. Neither the hairpin nor T-5 is required for intron excision or lariat formation during RNA splicing, but the 5'-exon sequence can affect the efficiency of exon ligation. Structural modeling suggests that the 5'-exon DNA hairpin and T-5 bind to the thumb and DNA-binding domains of GsI-IIC reverse transcriptase. This mode of DNA target site recognition enables the intron to proliferate to high copy number by recognizing numerous transcription terminators and then finding the best match for the EBS/IBS interactions within a short distance downstream.

Hyperglycaemic impairment of PAR2-mediated vasodilation: Prevention by inhibition of aortic endothelial sodium-glucose-co-Transporter-2 and minimizing oxidative stress.

Hyperglycaemia is a major contributor to diabetic cardiovascular disease with hyperglycaemia-induced endothelial dysfunction recognized as the initiating cause. Coagulation pathway-regulated proteinase-activated receptors (PARs) that can regulate vascular tone in vivo cause eNOS-mediated endothelium-dependent vasodilation; but, the impact of hyperglycaemia on this vasodilatory action of PAR stimulation and the signalling pathways involved are unknown. We hypothesized that vascular sodium-glucose co-transporter 2 activity and hyperglycaemia-induced oxidative stress involving Src-kinase, EGF receptor-kinase, Rho-kinase and protein-kinase-C biochemical signalling pathways would compromise PAR2-mediated endothelium-dependent vasodilation. Using an organ culture approach, wherein murine aorta rings were maintained for 24 h at hyperglycaemic 25 mM versus euglycaemic 10 mM glucose, we observed severely blunted acetylcholine/muscarinic and PAR2-mediated endothelial eNOS/NO-dependent vasodilation. PEG-catalase, superoxide-dismutase, and NADPH-oxidase inhibition (VAS2870) and either SGLT2-inhibition (canagliflozin/dapagliflozin/empagliflozin) or antioxidant gene induction (sulforaphane), prevented the hyperglycaemia-induced impairment of PAR2-mediated vasodilation. Similarly, inhibition of Src-kinase, EGF receptor-kinase, protein kinase-C and Rho-kinase also preserved PAR2-mediated vasodilation in tissues cultured under hyperglycaemic conditions. Thus, intracellular hyperglycaemia, that can be prevented with an inhibitor of the SGLT2 cotransporter that was identified in the vascular tissue and tissue-derived cultured endothelial cells by qPCR, western blot and immunohistochemistry, leads to oxidative stress that compromises PAR2-mediated NOS-dependent vasodilation by an NAPDH oxidase/reactive-oxygen-species-triggered signalling pathway involving EGFR/Src/Rho-kinase and PKC. The data point to novel antioxidant therapeutic strategies including use of an SGLT2 inhibitor and sulforaphane to mitigate hyperglycaemia-induced endothelial dysfunction.

Human pericardial proteoglycan 4 (lubricin): Implications for postcardiotomy intrathoracic adhesion formation.

OBJECTIVE: Intrapericardial fibrous adhesions increase the risk of sternal reentry. Proteoglycan 4/lubricin (PRG4) is a mucin-like glycoprotein that lubricates tissue compartments and prevents inflammation. We characterized PRG4 expression in human pericardium and examined its effects in vitro on human cardiac myofibroblast fibrotic activity and in vivo as a measure of its therapeutic potential to prevent adhesions. METHODS: Full-length PRG4 expression was determined using Western blot analysis and amplified luminescent proximity homogeneous assay in human pericardial tissues obtained at cardiotomy. The in vitro effects of PRG4 were investigated on human cardiac myofibroblasts for cell adhesion, collagen gel contraction, and cell-mediated extracellular matrix remodeling. The influence of PRG4 on pericardial homeostasis was determined in a chronic porcine animal model. RESULTS: PRG4 is expressed in human pericardial fluid and colocalized with pericardial mesothelial cells. Recombinant human PRG4 prevented human cardiac myofibroblast attachment and reduced myofibroblast activity assessed using collagen gel contraction assay (64.6% ± 8.1% vs 47.1% ± 6.8%; P = .02). Using a microgel assay, human cardiac myofibroblast mediated collagen fiber remodeling was attenuated by PRG4 (1.17 ± 0.03 vs 0.90 ± 0.05; P = .002). In vivo, removal of pericardial fluid alone induced severe intrapericardial adhesion formation, tissue thickening, and inflammatory fluid collections. Restoration of intrapericardial PRG4 was protective against fibrous adhesions and preserved the pericardial space. CONCLUSIONS: For the first time, we show that PRG4 is expressed in human pericardial fluid and regulates local fibrotic myofibroblast activity. Loss of PRG4-enriched pericardial fluid after cardiotomy might induce adhesion formation. Therapeutic restoration of intrapericardial PRG4 might prevent fibrous/inflammatory adhesions and reduce the risk of sternal reentry.

Bioactive Extracellular Matrix Scaffold Promotes Adaptive Cardiac Remodeling and Repair.

Structural cardiac remodeling after ischemic injury can induce a transition to heart failure from progressive loss of cardiac function. Cellular regenerative therapies are promising but face significant translational hurdles. Tissue extracellular matrix (ECM) holds the necessary environmental cues to stimulate cell-based endogenous myocardial repair pathways and promote adaptive remodeling toward functional recovery. Heart epicardium has emerged as an important anatomic niche for endogenous repair pathways including vasculogenesis and cardiogenesis. We show that acellular ECM scaffolds surgically implanted on the epicardium following myocardial infarction (MI) can attenuate structural cardiac remodeling and improve functional recovery. We assessed the efficacy of this strategy on post-MI functional recovery by comparing intact bioactive scaffolds with biologically inactivated ECM scaffolds. We confirm that bioactive properties within the acellular ECM biomaterial are essential for the observed functional benefits. We show that interaction of human cardiac fibroblasts with bioactive ECM can induce a robust cell-mediated vasculogenic paracrine response capable of functional blood vessel assembly. Fibroblast growth factor-2 is uncovered as a critical regulator of this novel bioinductive effect. Acellular bioactive ECM scaffolds surgically implanted on the epicardium post-MI can reprogram resident fibroblasts and stimulate adaptive pro-reparative pathways enhancing functional recovery. We introduce a novel surgical strategy for tissue repair that can be performed as an adjunct to conventional surgical revascularization with minimal translational challenges.

Valve-Related Hemodynamics Mediate Human Bicuspid Aortopathy: Insights From Wall Shear Stress Mapping.

BACKGROUND: Suspected genetic causes for extracellular matrix (ECM) dysregulation in the ascending aorta in patients with bicuspid aortic valves (BAV) have influenced strategies and thresholds for surgical resection of BAV aortopathy. Using 4-dimensional (4D) flow cardiac magnetic resonance imaging (CMR), we have documented increased regional wall shear stress (WSS) in the ascending aorta of BAV patients. OBJECTIVES: This study assessed the relationship between WSS and regional aortic tissue remodeling in BAV patients to determine the influence of regional WSS on the expression of ECM dysregulation. METHODS: BAV patients (n = 20) undergoing ascending aortic resection underwent pre-operative 4D flow CMR to regionally map WSS. Paired aortic wall samples (i.e., within-patient samples obtained from regions of elevated and normal WSS) were collected and compared for medial elastin degeneration by histology and ECM regulation by protein expression. RESULTS: Regions of increased WSS showed greater medial elastin degradation compared to adjacent areas with normal WSS: decreased total elastin (p = 0.01) with thinner fibers (p = 0.00007) that were farther apart (p = 0.001). Multiplex protein analyses of ECM regulatory molecules revealed an increase in transforming growth factor ß-1 (p = 0.04), matrix metalloproteinase (MMP)-1 (p = 0.03), MMP-2 (p = 0.06), MMP-3 (p = 0.02), and tissue inhibitor of metalloproteinase-1 (p = 0.04) in elevated WSS regions, indicating ECM dysregulation in regions of high WSS. CONCLUSIONS: Regions of increased WSS correspond with ECM dysregulation and elastic fiber degeneration in the ascending aorta of BAV patients, implicating valve-related hemodynamics as a contributing factor in the development of aortopathy. Further study to validate the use of 4D flow CMR as a noninvasive biomarker of disease progression and its ability to individualize resection strategies is warranted.

Retrieval practice over the long term: should spacing be expanding or equal-interval?

If multiple opportunities are available to review to-be-learned material, should a review occur soon after initial study and recur at progressively expanding intervals, or should the reviews occur at equal intervals? Landauer and Bjork (1978) argued for the superiority of expanding intervals, whereas more recent research has often failed to find any advantage. However, these prior studies have generally compared expanding versus equal-interval training within a single session, and have assessed effects only upon a single final test. We argue that a more generally important goal would be to maintain high average performance over a considerable period of training. For the learning of foreign vocabulary spread over four weeks, we found that expanding retrieval practice (i.e., sessions separated by increasing numbers of days) produced recall equivalent to that from equal-interval practice on a final test given eight weeks after training. However, the expanding schedule yielded much higher average recallability over the whole training period.

Melatonin induces histone hyperacetylation in the rat brain.

We have reported that melatonin induces histone hyperacetylation in mouse neural stem cells, suggesting an epigenetic role for this pleiotropic hormone. To support such a role, it is necessary to demonstrate that melatonin produces similar effects in vivo. Histone acetylation, following chronic treatment with melatonin (4µg/ml in drinking water for 17 days), was examined by western blotting in selected rat brain regions. Melatonin induced significant increases in histone H3 and histone H4 acetylation in the hippocampus. Histone H4 was also hyperacetylated in the striatum, but there were no significant changes in histone H3 acetylation in this brain region. No significant changes in the acetylation of either histone H3 or H4 were observed in the midbrain and cerebellum. An examination of kinase activation, which may be related to these changes, revealed that melatonin treatment increased the levels of phospho-ERK (extracellular signal-regulated kinase) in the hippocampus and striatum, but phospho-Akt (protein kinase B) levels were unchanged. These findings suggest that chromatin remodeling and associated changes in the epigenetic regulation of gene expression underlie the multiple physiological effects of melatonin.