A physics-informed deep learning framework for dynamic susceptibility contrast perfusion MRI.

BACKGROUND: Perfusion magnetic resonance imaging (MRI)s plays a central role in the diagnosis and monitoring of neurovascular or neurooncological disease. However, conventional processing techniques are limited in their ability to capture relevant characteristics of the perfusion dynamics and suffer from a lack of standardization. PURPOSE: We propose a physics-informed deep learning framework which is capable of analyzing dynamic susceptibility contrast perfusion MRI data and recovering the dynamic tissue response with high accuracy. METHODS: The framework uses physics-informed neural networks (PINNs) to learn the voxel-wise TRF, which represents the dynamic response of the local vascular network to the contrast agent bolus. The network output is stabilized by total variation and elastic net regularization. Parameter maps of normalized cerebral blood flow (nCBF) and volume (nCBV) are then calculated from the predicted residue functions. The results are validated using extensive comparisons to values derived by conventional Tikhonov-regularized singular value decomposition (TiSVD), in silico simulations and an in vivo dataset of perfusion MRI exams of patients with high-grade gliomas. RESULTS: The simulation results demonstrate that PINN-derived residue functions show a high concordance with the true functions and that the calculated values of nCBF and nCBV converge towards the true values for higher contrast-to-noise ratios. In the in vivo dataset, we find high correlations between conventionally derived and PINN-predicted perfusion parameters (Pearson's rho for nCBF: 0.84 ± 0.03 $0.84 \pm 0.03$ and nCBV: 0.92 ± 0.03 $0.92 \pm 0.03$ ) and very high indices of image similarity (structural similarity index for nCBF: 0.91 ± 0.03 $0.91 \pm 0.03$ and for nCBV: 0.98 ± 0.00 $0.98 \pm 0.00$ ). CONCLUSIONS: PINNs can be used to analyze perfusion MRI data and stably recover the response functions of the local vasculature with high accuracy.

Whole-Brain Vascular Architecture Mapping Identifies Region-Specific Microvascular Profiles In Vivo.

BACKGROUND AND PURPOSE: The novel MR imaging technique of vascular architecture mapping allows in vivo characterization of local changes in cerebral microvasculature, but reference ranges for vascular architecture mapping parameters in healthy brain tissue are lacking, limiting its potential applicability as an MR imaging biomarker in clinical practice. We conducted whole-brain vascular architecture mapping in a large cohort to establish vascular architecture mapping parameter references ranges and identify region-specific cortical and subcortical microvascular profiles. MATERIALS AND METHODS: This was a single-center examination of adult patients with unifocal, stable low-grade gliomas with multiband spin- and gradient-echo EPI sequence at 3T using parallel imaging. Voxelwise plotting of resulting values for gradient-echo (R2*) versus spin-echo (R2) relaxation rates during contrast agent bolus administration generates vessel vortex curves that allow the extraction of vascular architecture mapping parameters representative of, eg, vessel type, vessel radius, or CBV in the underlying voxel. Averaged whole-brain parametric maps were calculated for 9 parameters, and VOI analysis was conducted on the basis of a standardized brain atlas and individual cortical GM and WM segmentation. RESULTS: Prevalence of vascular risk factors among subjects (n = 106; mean age, 39.2 [SD, 12.5] years; 56 women) was similar to those in the German population. Compared with WM, we found cortical GM to have larger mean vascular calibers (5.80 [SD, 0.59] versus 4.25 [SD, 0.62] P < .001), increased blood volume fraction (20.40 [SD, 4.49] s-1 versus 11.05 [SD, 2.44] s-1; P < .001), and a dominance of venous vessels. Distinct microvascular profiles emerged for cortical GM, where vascular architecture mapping vessel type indicator differed, eg, between the thalamus and cortical GM (mean, -2.47 [SD, 4.02] s-2 versus -5.41 [SD, 2.84] s-2; P < .001). Intraclass correlation coefficient values indicated overall high test-retest reliability for vascular architecture mapping parameter mean values when comparing multiple scans per subject. CONCLUSIONS: Whole-brain vascular architecture mapping in the adult brain reveals region-specific microvascular profiles. The obtained parameter reference ranges for distinct anatomic and functional brain areas may be used for future vascular architecture mapping studies on cerebrovascular pathologies and might facilitate early discovery of microvascular changes, in, eg, neurodegeneration and neuro-oncology.

Patient, Relative and Staff Experiences of Clinical Trial Participation in Neurooncology: "Maybe You Can Also Show the Positive, No Matter How It Ends".

Purpose: There is a lack of evidence regarding how patients with malignant brain tumor and their relatives experience participation in neurooncological clinical trials. Similarly, insights from the perspective of trial staff caring for this group of patients are missing. This study aims to investigate patient, relative and trial staff experiences regarding participation in clinical neurooncological trials. Methods: Within a qualitative exploratory study, 29 semi-structured interviews with brain tumor patients, relatives and trial staff were conducted and analyzed using reflexive thematic analysis (RTA) by Braun and Clarke. A patient researcher and patient council were involved in data analysis and interpretation. Results: Four themes were developed reflecting significant aspects of the trial experience: 1. "It all revolves around hope"; 2. "Trial participation: experiencing unique medical care"; 3. "Everyone's roles are changing"; 4. "Communication as a possible area of conflict". Experiencing trial participation and general medical treatment were found to be interconnected to such a degree that they were often not meaningfully distinguished by patients and relatives. Conclusion: In addition to assessing traditional endpoints for patient outcomes, we recommend increased emphasis on investigating the impact of the "soft" components constituting trial participation. Due to the interconnectedness of medical treatment and trial participation, we recommend further investigation in comparison to experiences in regular care. A deeper understanding of trial participation is needed to inform improvements for patient experiences and staff satisfaction alongside medical and scientific progress.

The treatment options available to patients with (malignant) brain tumors are currently very limited. Therefore, patients are sometimes offered to participate in a clinical trial. This means that they receive an experimental treatment (eg new medicine) for which it is not yet clear whether it works better than regular medical care. Currently, little is known about how this group of patients, their relatives and the hospital staff who care for them experience the participation in these clinical trials ­ which is what we aimed to explore in our study reported here. Based on interviews with patients, relatives and staff, we found that: trial participation mainly revolves around hope;trial participation entails experiencing unique medical care;trial participation significantly changes the previous roles of patients, relatives and staff;trial participation intensifies communication as a possible area of conflict. By providing information on how patients, relatives and staff make sense of their trial experiences, this study constitutes an important addition to the traditional focus of clinical trials on medical and scientific endpoints (eg progression-free survival). This may help clinicians and researchers involved in cancer research and treatment to understand why "unsuccessful" trials can still be perceived as positive by patients or how hopeful communication may support their patients even when perceived as "unrealistic" from the clinicians' perspective. An in depth understanding of trial participation from the perspective of those affected is needed for improved care experiences alongside medical and scientific progress for cancer treatment.

Magnetization transfer ratio of the sciatic nerve differs between patients in type 1 and type 2 diabetes.

BACKGROUND: Previous studies on magnetic resonance neurography (MRN) found different patterns of structural nerve damage in type 1 diabetes (T1D) and type 2 diabetes (T2D). Magnetization transfer ratio (MTR) is a quantitative technique to analyze the macromolecular tissue composition. We compared MTR values of the sciatic nerve in patients with T1D, T2D, and healthy controls (HC). METHODS: 3-T MRN of the right sciatic nerve at thigh level was performed in 14 HC, 10 patients with T1D (3 with diabetic neuropathy), and 28 patients with T2D (10 with diabetic neuropathy). Results were subsequently correlated with clinical and electrophysiological data. RESULTS: The sciatic nerve's MTR was lower in patients with T2D (0.211 ± 0.07, mean ± standard deviation) compared to patients with T1D (T1D 0.285 ± 0.03; p = 0.015) and HC (0.269 ± 0.05; p = 0.039). In patients with T1D, sciatic MTR correlated positively with tibial nerve conduction velocity (NCV; r = 0.71; p = 0.021) and negatively with hemoglobin A1c (r = - 0.63; p < 0.050). In patients with T2D, we found negative correlations of sciatic nerve's MTR peroneal NCV (r = - 0.44; p = 0.031) which remained significant after partial correlation analysis controlled for age and body mass index (r = 0.51; p = 0.016). CONCLUSIONS: Lower MTR values of the sciatic nerve in T2D compared to T1D and HC and diametrical correlations of MTR values with NCV in T1D and T2D indicate that there are different macromolecular changes and pathophysiological pathways underlying the development of neuropathic nerve damage in T1D and T2D. TRIAL REGISTRATION: https://classic. CLINICALTRIALS: gov/ct2/show/NCT03022721 . 16 January 2017. RELEVANCE STATEMENT: Magnetization transfer ratio imaging may serve as a non-invasive imaging method to monitor the diseases progress and to encode the pathophysiology of nerve damage in patients with type 1 and type 2 diabetes. KEY POINTS: • Magnetization transfer imaging detects distinct macromolecular nerve lesion patterns in diabetes patients. • Magnetization transfer ratio was lower in type 2 diabetes compared to type 1 diabetes. • Different pathophysiological mechanisms drive nerve damage in type 1 and 2 diabetes.

Association of Small Fiber Function with Microvascular Perfusion of Peripheral Nerves in Patients with Type 2 Diabetes : Study using Quantitative Sensory Testing and Magnetic Resonance Neurography.

INTRODUCTION/AIMS: Diabetic small fiber neuropathy (SFN) is caused by damage to thinly myelinated A­fibers (δ) and unmyelinated C­fibers. This study aimed to assess associations between quantitative sensory testing (QST) and parameters of peripheral nerve perfusion obtained from dynamic contrast enhanced (DCE) magnetic resonance neurography (MRN) in type 2 diabetes patients with and without SFN. METHODS: A total of 18 patients with type 2 diabetes (T2D, 8 with SFN, 10 without SFN) and 10 healthy controls (HC) took part in this cross-sectional single-center study and underwent QST of the right leg and DCE-MRN of the right thigh with subsequent calculation of the sciatic nerve constant of capillary permeability (Ktrans), extravascular extracellular volume fraction (Ve), and plasma volume fraction (Vp). RESULTS: The Ktrans (HC 0.031 min-1 ± 0.009, T2D 0.043 min-1 ± 0.015; p = 0.033) and Ve (HC 1.2% ± 1.5, T2D: 4.1% ± 5.1; p = 0.027) were lower in T2D patients compared to controls. In T2D patients, compound z­scores of thermal and mechanical detection correlated with Ktrans (r = 0.73; p = 0.001, and r = 0.57; p = 0.018, respectively) and Ve (r = 0.67; p = 0.002, and r = 0.69; p = 0.003, respectively). Compound z­scores of thermal pain and Vp (r = -0.57; p = 0.015) correlated negatively. DISCUSSION: The findings suggest that parameters of peripheral nerve microcirculation are related to different symptoms in SFN: A reduced capillary permeability may result in a loss of function related to insufficient nutritional supply, whereas increased capillary permeability may be accompanied by painful symptoms related to a gain of function.

A diminished sciatic nerve structural integrity is associated with distinct peripheral sensory phenotypes in individuals with type 2 diabetes.

AIMS/HYPOTHESIS: Quantitative sensory testing (QST) allows the identification of individuals with rapid progression of diabetic sensorimotor polyneuropathy (DSPN) based on certain sensory phenotypes. Hence, the aim of this study was to investigate the relationship of these phenotypes with the structural integrity of the sciatic nerve among individuals with type 2 diabetes. METHODS: Seventy-six individuals with type 2 diabetes took part in this cross-sectional study and underwent QST of the right foot and high-resolution magnetic resonance neurography including diffusion tensor imaging of the right distal sciatic nerve to determine the sciatic nerve fractional anisotropy (FA) and cross-sectional area (CSA), both of which serve as markers of structural integrity of peripheral nerves. Participants were then assigned to four sensory phenotypes (participants with type 2 diabetes and healthy sensory profile [HSP], thermal hyperalgesia [TH], mechanical hyperalgesia [MH], sensory loss [SL]) by a standardised sorting algorithm based on QST. RESULTS: Objective neurological deficits showed a gradual increase across HSP, TH, MH and SL groups, being higher in MH compared with HSP and in SL compared with HSP and TH. The number of participants categorised as HSP, TH, MH and SL was 16, 24, 17 and 19, respectively. There was a gradual decrease of the sciatic nerve's FA (HSP 0.444, TH 0.437, MH 0.395, SL 0.382; p=0.005) and increase of CSA (HSP 21.7, TH 21.5, MH 25.9, SL 25.8 mm2; p=0.011) across the four phenotypes. Further, MH and SL were associated with a lower sciatic FA (MH unstandardised regression coefficient [B]=-0.048 [95% CI -0.091, -0.006], p=0.027; SL B=-0.062 [95% CI -0.103, -0.020], p=0.004) and CSA (MH ß=4.3 [95% CI 0.5, 8.0], p=0.028; SL B=4.0 [95% CI 0.4, 7.7], p=0.032) in a multivariable regression analysis. The sciatic FA correlated negatively with the sciatic CSA (r=-0.35, p=0.002) and markers of microvascular damage (high-sensitivity troponin T, urine albumin/creatinine ratio). CONCLUSIONS/INTERPRETATION: The most severe sensory phenotypes of DSPN (MH and SL) showed diminishing sciatic nerve structural integrity indexed by lower FA, likely representing progressive axonal loss, as well as increasing CSA of the sciatic nerve, which cannot be detected in individuals with TH. Individuals with type 2 diabetes may experience a predefined cascade of nerve fibre damage in the course of the disease, from healthy to TH, to MH and finally SL, while structural changes in the proximal nerve seem to precede the sensory loss of peripheral nerves and indicate potential targets for the prevention of end-stage DSPN. TRIAL REGISTRATION: ClinicalTrials.gov NCT03022721.

Rational design of a SOCS1-edited tumor-infiltrating lymphocyte therapy using CRISPR/Cas9 screens.

Cell therapies such as tumor-infiltrating lymphocyte (TIL) therapy have shown promise in the treatment of patients with refractory solid tumors, with improvement in response rates and durability of responses nevertheless sought. To identify targets capable of enhancing the antitumor activity of T cell therapies, large-scale in vitro and in vivo clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 screens were performed, with the SOCS1 gene identified as a top T cell-enhancing target. In murine CD8+ T cell-therapy models, SOCS1 served as a critical checkpoint in restraining the accumulation of central memory T cells in lymphoid organs as well as intermediate (Texint) and effector (Texeff) exhausted T cell subsets derived from progenitor exhausted T cells (Texprog) in tumors. A comprehensive CRISPR tiling screen of the SOCS1-coding region identified sgRNAs targeting the SH2 domain of SOCS1 as the most potent, with an sgRNA with minimal off-target cut sites used to manufacture KSQ-001, an engineered TIL therapy with SOCS1 inactivated by CRISPR/Cas9. KSQ-001 possessed increased responsiveness to cytokine signals and enhanced in vivo antitumor function in mouse models. These data demonstrate the use of CRISPR/Cas9 screens in the rational design of T cell therapies.

Insulin Resistance Is Associated With Reduced Capillary Permeability of Thigh Muscles in Patients With Type 2 Diabetes.

CONTEXT: Insulin-mediated microvascular permeability and blood flow of skeletal muscle appears to be altered in the condition of insulin resistance. Previous studies on this effect used invasive procedures in humans or animals. OBJECTIVE: The aim of this study was to demonstrate the feasibility of a noninvasive assessment of human muscle microcirculation via dynamic contrast-enhanced (DCE)-magnetic resonance imaging (MRI) of skeletal muscle in patients with type 2 diabetes (T2D). METHODS: A total of 56 participants (46 with T2D, 10 healthy controls [HC]) underwent DCE-MRI of the right thigh at 3 Tesla. The constant of the musculature's microvascular permeability (Ktrans), extravascular extracellular volume fraction (ve), and plasma volume fraction (vp) were calculated. RESULTS: In T2D patients, skeletal muscle Ktrans was lower (HC 0.0677 ± 0.002 min-1, T2D 0.0664 ± 0.002 min-1; P = 0.042) while the homeostasis model assessment (HOMA) index was higher in patients with T2D compared to HC (HC 2.72 ± 2.2, T2D 6.11 ± 6.2; P = .011). In T2D, Ktrans correlated negatively with insulin (r = -0.39, P = .018) and HOMA index (r = -0.38, P = .020). CONCLUSION: The results signify that skeletal muscle DCE-MRI can be employed as a noninvasive technique for the assessment of muscle microcirculation in T2D. Our findings suggest that microvascular permeability of skeletal muscle is lowered in patients with T2D and that a decrease in microvascular permeability is associated with insulin resistance. These results are of interest with regard to the impact of muscle perfusion on diabetic complications such as diabetic sarcopenia.

Reverse Engineering Tone-Deafness: Disrupting Pitch-Matching by Creating Temporary Dysfunctions in the Auditory-Motor Network.

Perceiving and producing vocal sounds are important functions of the auditory-motor system and are fundamental to communication. Prior studies have identified a network of brain regions involved in pitch production, specifically pitch matching. Here we reverse engineer the function of the auditory perception-production network by targeting specific cortical regions (e.g., right and left posterior superior temporal (pSTG) and posterior inferior frontal gyri (pIFG)) with cathodal transcranial direct current stimulation (tDCS)-commonly found to decrease excitability in the underlying cortical region-allowing us to causally test the role of particular nodes in this network. Performance on a pitch-matching task was determined before and after 20 min of cathodal stimulation. Acoustic analyses of pitch productions showed impaired accuracy after cathodal stimulation to the left pIFG and the right pSTG in comparison to sham stimulation. Both regions share particular roles in the feedback and feedforward motor control of pitched vocal production with a differential hemispheric dominance.

Sensitivity and engineered resistance of myeloid leukemia cells to BRD9 inhibition.

Here we show that acute myeloid leukemia (AML) cells require the BRD9 subunit of the SWI-SNF chromatin-remodeling complex to sustain MYC transcription, rapid cell proliferation and a block in differentiation. Based on these observations, we derived small-molecule inhibitors of the BRD9 bromodomain that selectively suppress the proliferation of mouse and human AML cell lines. To establish these effects as on-target, we engineered a bromodomain-swap allele of BRD9 that retains functionality despite a radically altered bromodomain pocket. Expression of this allele in AML cells confers resistance to the antiproliferative effects of our compound series, thus establishing BRD9 as the relevant cellular target. Furthermore, we used an analogous domain-swap strategy to generate an inhibitor-resistant allele of EZH2. To our knowledge, our study provides the first evidence for a role of BRD9 in cancer and reveals a simple genetic strategy for constructing resistance alleles to demonstrate on-target activity of chemical probes in cells.

BET Bromodomain Inhibition Releases the Mediator Complex from Select cis-Regulatory Elements.

The bromodomain and extraterminal (BET) protein BRD4 can physically interact with the Mediator complex, but the relevance of this association to the therapeutic effects of BET inhibitors in cancer is unclear. Here, we show that BET inhibition causes a rapid release of Mediator from a subset of cis-regulatory elements in the genome of acute myeloid leukemia (AML) cells. These sites of Mediator eviction were highly correlated with transcriptional suppression of neighboring genes, which are enriched for targets of the transcription factor MYB and for functions related to leukemogenesis. A shRNA screen of Mediator in AML cells identified the MED12, MED13, MED23, and MED24 subunits as performing a similar regulatory function to BRD4 in this context, including a shared role in sustaining a block in myeloid maturation. These findings suggest that the interaction between BRD4 and Mediator has functional importance for gene-specific transcriptional activation and for AML maintenance.

Structure-Based Design of an in Vivo Active Selective BRD9 Inhibitor.

Components of the chromatin remodelling switch/sucrose nonfermentable (SWI/SNF) complex are recurrently mutated in tumors, suggesting that altering the activity of the complex plays a role in oncogenesis. However, the role that the individual subunits play in this process is not clear. We set out to develop an inhibitor compound targeting the bromodomain of BRD9 in order to evaluate its function within the SWI/SNF complex. Here, we present the discovery and development of a potent and selective BRD9 bromodomain inhibitor series based on a new pyridinone-like scaffold. Crystallographic information on the inhibitors bound to BRD9 guided their development with respect to potency for BRD9 and selectivity against BRD4. These compounds modulate BRD9 bromodomain cellular function and display antitumor activity in an AML xenograft model. Two chemical probes, BI-7273 (1) and BI-9564 (2), were identified that should prove to be useful in further exploring BRD9 bromodomain biology in both in vitro and in vivo settings.

The transcriptional cofactor TRIM33 prevents apoptosis in B lymphoblastic leukemia by deactivating a single enhancer.

Most mammalian transcription factors (TFs) and cofactors occupy thousands of genomic sites and modulate the expression of large gene networks to implement their biological functions. In this study, we describe an exception to this paradigm. TRIM33 is identified here as a lineage dependency in B cell neoplasms and is shown to perform this essential function by associating with a single cis element. ChIP-seq analysis of TRIM33 in murine B cell leukemia revealed a preferential association with two lineage-specific enhancers that harbor an exceptional density of motifs recognized by the PU.1 TF. TRIM33 is recruited to these elements by PU.1, yet acts to antagonize PU.1 function. One of the PU.1/TRIM33 co-occupied enhancers is upstream of the pro-apoptotic gene Bim, and deleting this enhancer renders TRIM33 dispensable for leukemia cell survival. These findings reveal an essential role for TRIM33 in preventing apoptosis in B lymphoblastic leukemia by interfering with enhancer-mediated Bim activation.

A rationale to target the SWI/SNF complex for cancer therapy.

SWI/SNF is a multisubunit chromatin-remodeling complex that performs fundamental roles in gene regulation, cell lineage specification, and organismal development. Mutations that inactivate SWI/SNF subunits are found in nearly 20% of human cancers, which indicates that the proper functioning of this complex is necessary to prevent tumor formation in diverse tissues. Recent studies show that SWI/SNF-mutant cancers depend on residual SWI/SNF complexes for their aberrant growth, thus revealing synthetic lethal interactions that could be exploited for therapeutic purposes. Other studies reveal that certain acute leukemias and small cell lung cancers, which lack SWI/SNF mutations, can be vulnerable to inhibition of the SWI/SNF ATPase subunit BRG1, whereas several normal and malignant cell types do not show this sensitivity. Here, we review the emerging evidence that implicates SWI/SNF as a tumor-dependency and candidate drug target in human cancer.

Enhanced cortical connectivity in absolute pitch musicians: a model for local hyperconnectivity.

Connectivity in the human brain has received increased scientific interest in recent years. Although connection disorders can affect perception, production, learning, and memory, few studies have associated brain connectivity with graded variations in human behavior, especially among normal individuals. One group of normal individuals who possess unique characteristics in both behavior and brain structure is absolute pitch (AP) musicians, who can name the appropriate pitch class of any given tone without a reference. Using diffusion tensor imaging and tractography, we observed hyperconnectivity in bilateral superior temporal lobe structures linked to AP possession. Furthermore, volume of tracts connecting left superior temporal gyrus to left middle temporal gyrus predicted AP performance. These findings extend previous reports of exaggerated temporal lobe asymmetry, may explain the higher incidence of AP in special populations, and may provide a model for understanding the heightened connectivity that is thought to underlie savant skills and cases of exceptional creativity.

Inducing Disorders in Pitch Perception and Production: a Reverse-Engineering Approach.

To perceive and produce music accurately, the brain must represent, categorize, plan, and execute pitched information in response to environmental stimuli. Convergent methods from psychophysics, voxel-based morphometry, and diffusion tensor imaging with normal and tone-deaf (TD) subjects have shown that neural networks controlling pitch perception and production systems include bilateral frontotemporal networks. Although psychophysical and neuroimaging results are suggestive of a superior temporal and inferior frontal network responsible for pitch perception and production, active intervention of these areas is necessary to establish a causal connection between superior temporal and inferior frontal areas and pitch production ability. We sought to reverse-engineer the pitch perception-production network by noninvasive brain stimulation. Transcranial direct current stimulation (tDCS), a noninvasive brain-stimulation technique that is optimal for auditory research, was applied over superior temporal and inferior frontal regions. Pitch matching ability was assessed using an individually optimized pitch matching task administered after each stimulation session. Results showed diminished accuracy in pitch matching after cathodal stimulation over inferior frontal and superior temporal areas compared to sham control. Results demonstrate that intact function and connectivity of a distributed cortical network, centered around bilateral superior temporal and inferior frontal regions, are required for efficient neural interactions with musical sounds.

Atrial arrhythmogenicity in aged Scn5a+/DeltaKPQ mice modeling long QT type 3 syndrome and its relationship to Na+ channel expression and cardiac conduction.

Recent studies have reported that human mutations in Nav1.5 predispose to early age onset atrial arrhythmia. The present experiments accordingly assess atrial arrhythmogenicity in aging Scn5a+/KPQ mice modeling long QT3 syndrome in relationship to cardiac Na(+) channel, Nav1.5, expression. Atrial electrophysiological properties in isolated Langendorff-perfused hearts from 3- and 12-month-old wild type (WT), and Scn5a+/KPQ mice were assessed using programmed electrical stimulation and their Nav1.5 expression assessed by Western blot. Cardiac conduction properties were assessed electrocardiographically in intact anesthetized animals. Monophasic action potential recordings demonstrated increased atrial arrhythmogenicity specifically in aged Scn5a+/DeltaKPQ hearts. These showed greater action potential duration/refractory period ratios but lower atrial Nav1.5 expression levels than aged WT mice. Atrial Nav1.5 levels were higher in young Scn5a+/DeltaKPQ than young WT. These levels increased with age in WT but not Scn5a+/DeltaKPQ. Both young and aged Scn5a+/DeltaKPQ mice showed lower heart rates and longer PR intervals than their WT counterparts. Young Scn5a+/DeltaKPQ mice showed longer QT and QTc intervals than young WT. Aged Scn5a+/DeltaKPQ showed longer QRS durations than aged WT. PR intervals were prolonged and QT intervals were shortened in young relative to aged WT. In contrast, ECG parameters were similar between young and aged Scn5a+/DeltaKPQ. Aged murine Scn5a+/DeltaKPQ hearts thus exhibit an increased atrial arrhythmogenicity. The differing Nav1.5 expression and electrocardiographic indicators of slowed cardiac conduction between Scn5a+/DeltaKPQ and WT, which show further variations associated with aging, may contribute toward atrial arrhythmia in aged Scn5a+/DeltaKPQ hearts.

The Therapeutic Effects of Singing in Neurological Disorders.

Music making (playing an instrument or singing) is a multimodal activity that involves the integration of auditory and sensorimotor processes. The ability to sing in humans is evident from infancy, and does not depend on formal vocal training but can be enhanced by training. Given the behavioral similarities between singing and speaking, as well as the shared and distinct neural correlates of both, researchers have begun to examine whether singing can be used to treat some of the speech-motor abnormalities associated with various neurological conditions. This paper reviews recent evidence on the therapeutic effects of singing, and how it can potentially ameliorate some of the speech deficits associated with conditions such as stuttering, Parkinson's disease, acquired brain lesions, and autism. By reviewing the status quo, it is hoped that future research can help to disentangle the relative contribution of factors to why singing works. This may ultimately lead to the development of specialized or "gold-standard" treatments for these disorders, and to an improvement in the quality of life for patients.