Artificial intelligence-based risk stratification of atrial fibrillation among women with peripartum cardiomyopathy compared to other cardiomyopathies

Background

Atrial fibrillation (AF) is diagnosed in up to 50% of patients with heart failure. However, the prevalence of AF among patients with peripartum cardiomyopathy (PPCM) ranges from only 2–10%, with the lowest rates in Black women. An artificial intelligence enhanced electrocardiogram (AI-ECG) has previously been shown to be effective in detecting AF while in sinus rhythm, and for AF risk prediction in a population-based study.

Purpose

Our objective was to evaluate the use of an AI-ECG for AF risk stratification among women of reproductive age (18 to 49 years) with PPCM compared to other forms of cardiomyopathy.

Methods

We identified 59 reproductive age women with a diagnosis of PPCM between January 2007, and October 2018 and included matched controls in a 3:1 fashion. Matching was performed based on sex, age, race, and left ventricular ejection fraction. We excluded patients with a diagnosis of AF prior to cardiomyopathy diagnosis date. AI-ECG prediction probabilities were generated for ECGs performed within a 30-day window prior to the patient's first cardiomyopathy diagnosis date for the entire study cohort.

Results

A total of 236 patients were included in the final analysis (59 cases, 177 controls). Overall, the median age at cardiomyopathy diagnosis was 31.7 years (IQR: 18.5, 49.4), 76.3% were White, 8.5% were Black, and 15.3% represented other or unknown race. Over the period studied, 3.4% of women with PPCM developed AF compared to 5.6% of women with other cardiomyopathies. The frequency of positive AI-ECG predictions for AF was more common among women with other cardiomyopathies (40.7%) compared to women with PPCM (20.3%). The predicted odds ratio for AF development following a cardiomyopathy diagnosis based on AI-ECG results was 0.37 (95% CI: 0.18, 0.73) for PPCM compared to other cardiomyopathies (p=0.006).

Conclusion

We demonstrated that an AI-ECG model for AF prediction may play a potential role in arrhythmia risk stratification/prediction among young women with PPCM who have a demonstrable lower risk for AF compared to women with other cardiomyopathies. Mechanisms for lower AF risk among patients with PPCM remain unknown. Further studies evaluating mechanistic pathways will be essential.

Funding Acknowledgement

Type of funding sources: None.

Structural and Morphological Analysis of the First Alloy/Dealloy of a Bulk Si-Li System at Elevated Temperature

There have been tremendous improvements in the field of Si electrode materials, either by nanoscale or composite routes, and though silicon-containing carbon electrode materials have begun to penetrate the marketplace, the commercial capacities achieved by these cells still fall short of the promise of high capacity Si electrodes. Enabling a cheaper feedstock of Si in the bulk form would make this technology more accessible, though there are many challenges that must be overcome. Whereas other methods utilize nanomaterials and composites to overcome volume expansion and pulverization of a Si electrode, this study explores a thermal route to enable the use of carbon-free bulk Si. To accomplish this, a modified Swagelok cell has been constructed to accommodate high temperatures, corrosive molten salt electrolytes, and a molten lithium electrode to study lithiation of a bulk Si wafer at 250 °C. Scanning electron microscopy, X-ray diffraction, and microcomputed tomography were used to examine morphological and structural changes within the Si upon lithiation and delithiation. It was discovered that semiordered Li _x Si phases were formed upon lithiation in molten LiTFSI electrolyte at 250 °C, and the higher temperature does not completely mitigate pulverization of the bulk Si electrode.

Machine learning predicts all-cause mortality in patients with severe aortic regurgitation

Funding Acknowledgements

Type of funding sources: None.

Background

Aortic regurgitation (AR) is a common valvular lesion associated with left ventricular (LV) enlargement and dysfunction and increased risk of death with onset of symptoms, significant LV enlargement, or systolic dysfunction. The current guidelines are based on symptoms, LV size and LV function to evaluate the candidacy for surgery in patients with severe AR.

Purpose

 We propose a machine-learning (ML) based algorithm to identify patients at risk for death from AR independent of aortic valve replacement (AVR) surgery (patients were censored at AVR event unless the operation occurred within 100 days of the first visit, in which case baseline AVR is included as a predictor).

Methods

The model was trained with 5-fold cross-validation on a dataset of 1035 patients. Model performance is reported on an independent dataset of 207 patients. Optimal predictive performance was observed with a Conditional Random Survival Forest model. A subset of 19 / 41 variables were selected for inclusion in the final model. Variable selection was performed with 10-fold cross validation using Random Survival Forest model; variables that were on an average selected by less than 6/10 splits were excluded.

Results

The mean age of patients was 60 ± 17 years and 198 (18%) were females. The variables included in the models were age, end-diastolic volume, end systolic dimension, body surface area, ejection fraction, NYHA class, body mass index, diastolic blood pressure, bicuspid valve, regurgitant volume, filling pressure, mid ascending aorta diameter, mitral tissue early relaxation velocity, pulmonary artery systolic pressure, and comorbidities, and the relative variable importances averaged across five splits of cross validation in each repeat were evaluated (Figure). The predictive AUC for predicting survival of the best-performing model was 0.84 at 1 year, 0.86 at 2 years, and 0.87 overall, respectively.

Conclusion

Using commonly observed echo parameters and patient characteristics we successfully trained a ML model to predict survival in patients with severe AR. This technique could identify high-risk patients who would benefit from early intervention, thereby improving patient outcomes. Abstract Figure.

Detecting cardiomyopathies in pregnancy and the postpartum period using ECG

Background

Cardiovascular disease (CVD) has been identified as a major threat to maternal health in the US and UK with cardiomyopathy being one of the most common acquired CVD in the pregnant and postpartum period. Diagnosing cardiomyopathy in pregnancy is challenging due to an overlap of cardiovascular symptoms with normal pregnancy symptoms.

Purpose

The purpose of this study was to evaluate the effectiveness of an ECG based deep learning model in identifying cardiomyopathy among pregnant and postpartum women.

Methods

We utilized an ECG based deep learning model to detect cardiomyopathy in a cohort of pregnant or postpartum women seen at multiple hospital sites. Model performance was evaluated using area under the curve (AUC), accuracy, sensitivity, and specificity. We compared the diagnostic probabilities of the deep learning model with natriuretic peptides and a multivariable model consisting of demographic and clinical parameters.

Results

1,807 women were included. 7%, 10% and 13% had LVEF ≤35%, <45% and <50% respectively. The ECG based deep learning model identified cardiomyopathy with an AUC of 0.92 for left ventricular ejection fraction (LVEF) ≤35%, 0.89 for LVEF <45% and 0.87 for LVEF <50%. For LVEF ≤35%, AUC was higher in Black (0.95) and Hispanic (0.98) women compared to white (0.91). Natriuretic peptides and the multivariable model had AUCs of 0.85 and 0.72 respectively.

Conclusions

A deep learning model effectively identifies cardiomyopathy in pregnant or postpartum women, outperforms natriuretic peptides and traditional clinical parameters with the potential to become a powerful initial screening tool for cardiomyopathy in the obstetric care setting.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): This study was made possible using resources supported by the Mayo Clinic Women's Health Research Center and the Mayo Clinic Building Interdisciplinary Research Careers in Women's Health (BIRCWH) Program funded by the National Institutes of Health (NIH), grant number K12 HD065987. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Does gadolinium improve magnetic resonance arthrography of the hip beyond fluid distension alone?

AIM

To determine if there is a difference in the detection of labral tears and cartilage lesions using the T2-weighted sequences of magnetic resonance arthrography (MRA) only, which simulate MRA with saline alone, compared with the full examination including T1-weighted sequences.

MATERIALS AND METHODS

One hundred hip MRA examinations performed at 3 T were identified retrospectively. Each study was reviewed by a musculoskeletal radiologist using either the T2-weighted sequences only (without gadolinium-based contrast agent [GBCA] effect) or the entire examination, including T1-weighted sequences (with GBCA effect). Receiver operating characteristic (ROC) curves were calculated for both groups and compared within a non-inferiority framework, using - 0.10 as the limit of non-inferiority.

RESULTS

For labral tears, the difference area under the curve (AUC) was -0.004 (95% confidence interval [CI]: -0.064-0.056, p=0.90). For acetabular cartilage lesions, the difference AUC was 0.011 (95% CI: -0.073-0.096, p=0.79). For femoral cartilage lesions, the difference AUC was -0.059 (95% CI: -0.206-0.087, p=0.43).

CONCLUSION

T2-weighted sequences alone were not inferior in diagnostic accuracy compared with the full examination (including T1-weighted sequences with intra-articular GBCA) in detecting acetabular cartilage lesions and labral tears. Further study with prospective comparison of saline injectate to GBCA-containing injectate may help clarify the necessity of continued GBCA use in MRA of the hip.

Point-of-Care Ultrasonography

Point-of-care ultrasonography (POCUS) is performed by a physician at the bedside and is standard practice in obstetric, emergency, and musculoskeletal medicine. When compared with formal sonography, POCUS is equivalent in screening for abdominal aortic aneurysm and as accurate in diagnosing deep venous thrombosis. POCUS has high accuracy for diagnosing pneumonia and detecting acute decompensated heart failure but is less accurate than computed tomography for identifying pulmonary embolism. POCUS confirmation of intrauterine pregnancy rules out an ectopic pregnancy. In the third trimester of high-risk pregnancies, umbilical artery Doppler ultrasonography can improve perinatal outcomes. Musculoskeletal POCUS is used to diagnose and guide treatment of many joint and soft tissue conditions. It is as accurate as magnetic resonance imaging in the diagnosis of complete rotator cuff tears. Ultrasound guidance improves outcomes in the placement of central venous catheters and fluid drainage from body cavities and lumbar punctures. Ultrasonography can reduce the use of CT for diagnosis of appendicitis; however, negative scan results do not rule out disease. POCUS can accurately diagnose and rule out gallbladder pathology, and is effective for diagnosing urolithiasis. Focused cardiac ultrasonography can detect pericardial effusion and decreased systolic function, but is less accurate than lung ultrasonography at diagnosing acute heart failure. Limited evidence demonstrates a benefit of diagnosing testicular and gynecologic conditions. The American College of Emergency Physicians, the American Institute of Ultrasound in Medicine, the Society for Academic Emergency Medicine, the American College of Radiology, and others offer POCUS training. Training standards for POCUS have been defined for residency programs but are less established for credentialing.

Evaluation of Lower-Dose Spiral Head CT for Detection of Intracranial Findings Causing Neurologic Deficits

BACKGROUND AND PURPOSE

Despite the frequent use of unenhanced head CT for the detection of acute neurologic deficit, the radiation dose for this exam varies widely. Our aim was to evaluate the performance of lower-dose head CT for detection of intracranial findings resulting in acute neurologic deficit.

MATERIALS AND METHODS

Projection data from 83 patients undergoing unenhanced spiral head CT for suspected neurologic deficits were collected. Cases positive for infarction, intra-axial hemorrhage, mass, or extra-axial hemorrhage required confirmation by histopathology, surgery, progression of findings, or corresponding neurologic deficit; cases negative for these target diagnoses required negative assessments by two neuroradiologists and a clinical neurologist. A routine dose head CT was obtained using 250 effective mAs and iterative reconstruction. Lower-dose configurations were reconstructed (25-effective mAs iterative reconstruction, 50-effective mAs filtered back-projection and iterative reconstruction, 100-effective mAs filtered back-projection and iterative reconstruction, 200-effective mAs filtered back-projection). Three neuroradiologists circled findings, indicating diagnosis, confidence (0-100), and image quality. The difference between the jackknife alternative free-response receiver operating characteristic figure of merit at routine and lower-dose configurations was estimated. A lower 95% CI estimate of the difference greater than -0.10 indicated noninferiority.

RESULTS

Forty-two of 83 patients had 70 intracranial findings (29 infarcts, 25 masses, 10 extra- and 6 intra-axial hemorrhages) at routine head CT (CT dose index = 38.3 mGy). The routine-dose jackknife alternative free-response receiver operating characteristic figure of merit was 0.87 (95% CI, 0.81-0.93). Noninferiority was shown for 100-effective mAs iterative reconstruction (figure of merit difference, -0.04; 95% CI, -0.08 to 0.004) and 200-effective mAs filtered back-projection (-0.02; 95% CI, -0.06 to 0.02) but not for 100-effective mAs filtered back-projection (-0.06; 95% CI, -0.10 to -0.02) or lower-dose levels. Image quality was better at higher-dose levels and with iterative reconstruction (P < .05).

CONCLUSIONS

Observer performance for dose levels using 100-200 eff mAs was noninferior to that observed at 250 effective mAs with iterative reconstruction, with iterative reconstruction preserving noninferiority at a mean CT dose index of 15.2 mGy.

Comparison of a Photon-Counting-Detector CT with an Energy-Integrating-Detector CT for Temporal Bone Imaging: A Cadaveric Study

BACKGROUND AND PURPOSE

Evaluating abnormalities of the temporal bone requires high-spatial-resolution CT imaging. Our aim was to assess the performance of photon-counting-detector ultra-high-resolution acquisitions for temporal bone imaging and compare the results with those of energy-integrating-detector ultra-high-resolution acquisitions.

MATERIALS AND METHODS

Phantom studies were conducted to quantify spatial resolution of the ultra-high-resolution mode on a prototype photon-counting-detector CT scanner and an energy-integrating-detector CT scanner that uses a comb filter. Ten cadaveric temporal bones were scanned on both systems with the radiation dose matched to that of the clinical examinations. Images were reconstructed using a sharp kernel, 0.6-mm (minimum) thickness for energy-integrating-detector CT, and 0.6- and 0.25-mm (minimum) thicknesses for photon-counting-detector CT. Image noise was measured and compared using adjusted 1-way ANOVA. Images were reviewed blindly by 3 neuroradiologists to assess the incudomallear joint, stapes footplate, modiolus, and overall image quality. The ranking results for each specimen and protocol were compared using the Friedman test. The Krippendorff α was used for interreader agreement.

RESULTS

Photon-counting-detector CT showed an increase of in-plane resolution compared with energy-integrating-detector CT. At the same thickness (0.6 mm), images from photon-counting-detector CT had significantly lower (P < .001) image noise compared with energy-integrating-detector CT. Readers preferred the photon-counting-detector CT images to the energy-integrating-detector images for all 3 temporal bone structures. A moderate interreader agreement was observed with the Krippendorff α = 0.50. For overall image quality, photon-counting-detector CT image sets were ranked significantly higher than images from energy-integrating-detector CT (P < .001).

CONCLUSIONS

This study demonstrated substantially better delineation of fine anatomy for the temporal bones scanned with the ultra-high-resolution mode of photon-counting-detector CT compared with the ultra-high-resolution mode of a commercial energy-integrating-detector CT scanner.

Tunable Mechanochemistry of Lithium Battery Electrodes

The interplay between mechanical strains and battery electrochemistry, or the tunable mechanochemistry of batteries, remains an emerging research area with limited experimental progress. In this report, we demonstrate how elastic strains applied to vanadium pentoxide (V₂O₅), a widely studied cathode material for Li-ion batteries, can modulate the kinetics and energetics of lithium-ion intercalation. We utilize atomic layer deposition to coat V₂O₅ materials onto the surface of a shapememory superelastic NiTi alloy, which allows electrochemical assessment at a fixed and measurable level of elastic strain imposed on the V₂O₅, with strain state assessed through Raman spectroscopy and X-ray diffraction. Our results indicate modulation of electrochemical intercalation potentials by ∼40 mV and an increase of the diffusion coefficient of lithium ions by up to 2.5-times with elastic prestrains of <2% imposed on the V₂O₅. These results are supported by density functional theory calculations and demonstrate how mechanics of nanomaterials can be used as a precise tool to strain engineer the electrochemical energy storage performance of battery materials.

Low-Dose CT for Craniosynostosis: Preserving Diagnostic Benefit with Substantial Radiation Dose Reduction

BACKGROUND AND PURPOSE

Given the positive impact of early intervention for craniosynostosis, CT is often performed for evaluation but radiation dosage remains a concern. We evaluated the potential for substantial radiation dose reduction in pediatric patients with suspected craniosynostosis.

MATERIALS AND METHODS

CT projection data from pediatric patients undergoing head CT for suspected craniosynostosis were archived. Simulated lower-dose CT images corresponding to 25%, 10%, and 2% of the applied dose were created using a validated method. Three neuroradiologists independently interpreted images in a blinded, randomized fashion. All sutures were evaluated by using 3D volume-rendered images alone, and subsequently with 2D and 3D images together. Reference standards were defined by reader agreement by using routine dose and 2D and 3D images. Performance figures of merit were calculated based on reader response and confidence.

RESULTS

Of 33 pediatric patients, 21 had craniosynostosis (39 positive sutures and 225 negative sutures). The mean volume CT dose index was 15.5 ± 2.3 mGy (range, 9.69-19.38 mGy) for the routine dose examination. Average figures of merit for multireader analysis ranged from 0.92 (95% CI, 0.90-0.95) at routine pediatric dose to 0.86 (95% CI, 0.79-0.94) at 2% dose using 3D images alone. Similarly, pooled reader figures of merit ranged from 0.91 (95% CI, 0.89-0.95) at routine pediatric dose to 0.85 (95% CI, 0.76-0.95) at 2% dose using 2D and 3D images together. At 25% and 10% dose, 95% CI of the difference in figures of merit from routine dose included 0, suggesting similar or noninferior performance.

CONCLUSIONS

For pediatric head CT for evaluation of craniosynostosis, dose reductions of 75%-90% were possible without compromising observer performance.

Mechanism of potassium ion intercalation staging in few layered graphene from in situ Raman spectroscopy

Recently emerging potassium ion (K-ion) batteries offer a lower-cost alternative to lithium-ion batteries while enabling comparably high storage capacity. Here, we leverage the strong Raman spectroscopic response of few-layered graphene to provide the first insight into the electrochemical staging sequence for K⁺ ions in graphitic carbons. Our analysis reveals the signature of a dilute stage I compound that precedes formation of ordered intercalation compounds transitioning from stage VI (KC₇₂), stage II (KC₂₄), and stage I (KC₈) and correlates electrochemical responses to the stage formation. Overall, our study emphasizes a minimum barrier to transfer the general understanding acquired for lithium-ion battery anodes to cheaper, earth abundant K-ion battery systems ideally suited for grid-scale storage.

Temporal Bone CT: Improved Image Quality and Potential for Decreased Radiation Dose Using an Ultra-High-Resolution Scan Mode with an Iterative Reconstruction Algorithm

BACKGROUND AND PURPOSE

Radiation dose in temporal bone CT imaging can be high due to the requirement of high spatial resolution. In this study, we assessed whether CT imaging of the temporal bone by using an ultra-high-resolution scan mode combined with iterative reconstruction provides higher spatial resolution and lower image noise than a z-axis ultra-high-resolution mode.

MATERIALS AND METHODS

Patients with baseline temporal bone CT scans acquired by using a z-axis ultra-high-resolution protocol and a follow-up scan by using the ultra-high-resolution-iterative reconstruction technique were identified. Images of left and right temporal bones were reconstructed in the axial, coronal, and Poschl planes. Three neuroradiologists assessed the spatial resolution of the following structures: round and oval windows, incudomallear and incudostapedial joints, basal turn spiral lamina, and scutum. The paired z-axis ultra-high-resolution and ultra-high-resolution-iterative reconstruction images were displayed side by side in random order, with readers blinded to the imaging protocol. Image noise was compared in ROIs over the posterior fossa.

RESULTS

We identified 8 patients, yielding 16 sets of temporal bone images (left and right). Three sets were excluded because the patient underwent surgery between the 2 examinations. Spatial resolution was comparable (Poschl) or slightly better (axial and coronal planes) with ultra-high-resolution-iterative reconstruction than with z-axis ultra-high-resolution. A paired t test indicated that noise was significantly lower with ultra-high-resolution-iterative reconstruction than with z-axis ultra-high-resolution (P < .001), with a mean noise reduction of 37% (range, 18%-49%).

CONCLUSIONS

The ultra-high-resolution-iterative reconstruction scan mode has similar or slightly better resolution relative to the z-axis ultra-high-resolution mode for CT of the temporal bone but significantly (P < .01) lower image noise, which may enable the dose to be reduced by approximately 50%.

All silicon electrode photocapacitor for integrated energy storage and conversion

We demonstrate a simple wafer-scale process by which an individual silicon wafer can be processed into a multifunctional platform where one side is adapted to replace platinum and enable triiodide reduction in a dye-sensitized solar cell and the other side provides on-board charge storage as an electrochemical supercapacitor. This builds upon electrochemical fabrication of dual-sided porous silicon and subsequent carbon surface passivation for silicon electrochemical stability. The utilization of this silicon multifunctional platform as a combined energy storage and conversion system yields a total device efficiency of 2.1%, where the high frequency discharge capability of the integrated supercapacitor gives promise for dynamic load-leveling operations to overcome current and voltage fluctuations during solar energy harvesting.

Bisphenol diglycidyl ethers and bisphenol A and their hydrolysis in drinking water

Epoxy coatings are commonly used to protect the interior (and exterior) surfaces of water mains and storage tanks and can be used on the interior surfaces of water pipes in homes, hospitals, hotels, and other buildings. Common major components of epoxies include bisphenols, such as bisphenol A (BPA) or bisphenol F (BPF), and their reactive prepolymers, bisphenol A diglycidyl ether (BADGE) and bisphenol F diglycidyl ether (BFDGE), respectively. There currently are health concerns about the safety of BPA and BPF due to known estrogenic effects. Determination of key bisphenol leachates, development of a hydrolysis model, and identification of stable hydrolysis products will aid in assessment of human bisphenol exposure through ingestion of drinking water. Liquid chromatography/mass spectrometry (LC/MS/MS) was used for quantitation of key analytes, and a pseudo-first order kinetic approach was used for modeling. In fill-and-dump studies on epoxy-coated pipe specimens, BADGE and a BPA-like compound were identified as leachates. The BADGE hydrolysis model predicts BADGE half-lives at pH 7 and 15, 25, 35, and 40 °C to be 11, 4.6, 2.0, and 1.4 days respectively; the BFDGE half-life was 5 days at pH 7 and 25 °C. The two identified BADGE hydrolysis products are BADGE-H2O and BADGE 2H2O, with BADGE 2H2O being the final end product under the conditions studied.

Correlation of the Patient Reported Outcomes Measurement Information System with legacy outcomes measures in assessment of response to lumbar transforaminal epidural steroid injections

BACKGROUND AND PURPOSE

The Patient Reported Outcomes Measurement Information System is a newly developed outcomes measure promulgated by the National Institutes of Health. This study compares changes in pain and physical function-related measures of this system with changes on the Numeric Rating Pain Scale, Roland Morris Disability Index, and the European Quality of Life scale 5D questionnaire in patients undergoing transformational epidural steroid injections for radicular pain.

MATERIALS AND METHODS

One hundred ninety-nine patients undergoing transforaminal epidural steroid injections for radicular pain were enrolled in the study. Before the procedure, they rated the intensity of their pain by using the 0-10 Numeric Rating Pain Scale, Roland Morris Disability Index, and European Quality of Life scale 5D questionnaire. Patients completed the Patient Reported Outcomes Measurement Information System Physical Function, Pain Behavior, and Pain Interference short forms before transforaminal epidural steroid injections and at 3 and 6 months. Seventy and 43 subjects replied at 3- and 6-month follow-up. Spearman rank correlations were used to assess the correlation between the instruments. The minimally important differences were calculated for each measurement tool as an indicator of meaningful change.

RESULTS

All instruments were responsive in detecting changes at 3- and 6-month follow-up (P < .0001). There was significant correlation between changes in Patient Reported Outcomes Measurement Information System scores and legacy questionnaires from baseline to 3 months (P < .05). There were, however, no significant correlations in changes from 3 to 6 months with any of the instruments.

CONCLUSIONS

The studied Patient Reported Outcomes Measurement Information System domains offered responsive and correlative psychometric properties compared with legacy instruments in a population of patients undergoing transforaminal epidural steroid injections for radicular pain.

On-chip high power porous silicon lithium ion batteries with stable capacity over 10,000 cycles

We demonstrate the operation of a graphene-passivated on-chip porous silicon material as a high rate lithium battery anode with over 50 X power density, and 100 X energy density improvement compared to identically prepared on-chip supercapacitors. We demonstrate this Faradaic storage behavior to occur at fast charging rates (1-10 mA cm(-2)) where lithium locally intercalates into the nanoporous silicon, preventing the degradation and poor cycling performance attributed to deep storage in the bulk silicon. This device exhibits cycling performance that exceeds 10,000 cycles with capacity above 0.1 mA h cm(-2) without notable capacity fade. This demonstrates a practical route toward high power, high energy, and long lifetime all-silicon on-chip storage systems relevant toward integration into electronics, photovoltaics, and other silicon-based platforms.

Tungsten diselenide (WSe2) as a high capacity, low overpotential conversion electrode for sodium ion batteries

Tungsten diselenide (WSe₂) is demonstrated as an efficient electrode for sodium ion batteries for the first time.

Intramedullary spinal cord metastases: prognostic value of MRI and clinical features from a 13-year institutional case series

BACKGROUND AND PURPOSE

In patients with intramedullary spinal cord metastases, the impact of MR imaging and clinical characteristics on survival has not been elucidated. Our aim was to identify MR imaging and clinical features with prognostic value among patients with intramedullary spinal cord metastases from a large retrospective series.

MATERIALS AND METHODS

The relevant MR imaging examination and baseline clinical data for each patient from a consecutive group of patients with intramedullary spinal cord metastases had previously been reviewed by 2 neuroradiologists. Additional relevant clinical data were extracted. The influence of clinical and imaging characteristics on survival was assessed by Kaplan-Meier survival curves and log-rank tests for categoric characteristics.

RESULTS

Forty-nine patients had 70 intramedullary spinal cord metastases; 10 (20%) of these patients had multiple metastases. From the date of diagnosis, median survival for all patients was 104 days (95% CI, 48-156 days). One clinical feature was associated with decreased median survival: lung or breast primary malignancy (57 days) compared with all other malignancy types (308 days; P < .001). Three MR imaging features were associated with decreased median survival: multiple intramedullary spinal cord metastases (53 versus 121 days, P = .022), greater longitudinal extent of cord T2 hyperintensity (if ≥3 segments, 111 days; if ≤2, 184 days; P = .018), and ancillary visualization of the primary tumor and/or non-CNS metastases (96 versus 316 days, P = .012).

CONCLUSIONS

Spinal cord edema spanning multiple segments, the presence of multifocal intramedullary spinal cord metastases, and ancillary evidence for non-CNS metastases and/or the primary tumor are MR imaging features associated with decreased survival and should be specifically sought. Patients with either a lung or breast primary malignancy are expected to have decreased survival compared with other primary tumor types.

Intramedullary spinal cord metastases: MRI and relevant clinical features from a 13-year institutional case series

BACKGROUND AND PURPOSE

Because intramedullary spinal cord metastasis is often a difficult diagnosis to make, our purpose was to perform a systematic review of the MR imaging and relevant baseline clinical features of intramedullary spinal cord metastases in a large series.

MATERIALS AND METHODS

Consecutive patients with intramedullary spinal cord metastasis with available pretreatment digital MR imaging examinations were identified. The MR imaging examination(s) for each patient was reviewed by 2 neuroradiologists for various imaging characteristics. Relevant clinical data were obtained.

RESULTS

Forty-nine patients had 70 intramedullary spinal cord metastases, with 10 (20%) having multiple intramedullary spinal cord metastases; 8% (4/49) were asymptomatic. Primary tumor diagnosis was preceded by intramedullary spinal cord metastasis presentation in 20% (10/49) and by intramedullary spinal cord metastasis diagnosis in 10% (5/49); 98% (63/64) of intramedullary spinal cord metastases enhanced. Cord edema was extensive: mean, 4.5 segments, 3.6-fold larger than enhancing lesion, and ≥3 segments in 54% (37/69). Intratumoral cystic change was seen in 3% (2/70) and hemorrhage in 1% (1/70); 59% (29/49) of reference MR imaging examinations displayed other CNS or spinal (non-spinal cord) metastases, and 59% (29/49) exhibited the primary tumor/non-CNS metastases, with 88% (43/49) displaying ≥1 finding and 31% (15/49) displaying both findings. Patients with solitary intramedullary spinal cord metastasis were less likely than those with multiple intramedullary spinal cord metastases to have other CNS or spinal (non-spinal cord) metastases on the reference MR imaging (20/39 [51%] versus 9/10 [90%], respectively; P = .0263).

CONCLUSIONS

Lack of known primary malignancy or spinal cord symptoms should not discourage consideration of intramedullary spinal cord metastasis. Enhancement and extensive edema for lesion size (often ≥3 segments) are typical for intramedullary spinal cord metastasis. Presence of cystic change/hemorrhage makes intramedullary spinal cord metastasis unlikely. Evidence for other CNS or spinal (non-spinal cord) metastases and the primary tumor/non-CNS metastases are common. The prevalence of other CNS or spinal (non-spinal cord) metastases in those with multiple intramedullary spinal cord metastases is especially high.

Facet joint signal change on MRI at levels of acute/subacute lumbar compression fractures

BACKGROUND AND PURPOSE

The prevalence of facet joint signal change in acute/subacute lumbar vertebral body compression fractures is unknown. We hypothesized that facet joint signal change on MR imaging is more common in facet joints associated with an acute/subacute lumbar compression fracture than those associated with normal vertebral bodies or ones that have a chronic compression fracture.

MATERIALS AND METHODS

Three neuroradiologists and a neuroradiology fellow retrospectively graded facet joint inflammatory change on MR imaging in 900 facet joints in 75 patients with at least 1 painful osteoporotic lumbar compression fracture. Facet joint signal change was assessed on T2-weighted images with chemical fat-saturation, STIR images, and/or gadolinium-enhanced T1-weighted images with chemical fat-saturation. Each facet joint from the T12/L1 to L5/S1 level was assessed individually. An overall facet joint signal-change score, which is a composite measure of the grade of signal change for all 4 facet joints associated with a given lumbar vertebral level, was devised, and statistical significance was assessed via Wilcoxon rank sum tests.

RESULTS

The overall facet joint signal-change scores were significantly higher at vertebral body levels affected by an acute/subacute compression fracture compared with control levels, which were associated with either normal bodies or chronic compression fractures.

CONCLUSIONS

Our findings suggest an association between facet joint signal change on MR imaging and acute/subacute lumbar vertebral body compression fractures.

Interobserver variability in retreatment decisions of recurrent and residual aneurysms

BACKGROUND AND PURPOSE

The degree of variation in retreatment decisions for residual or recurrent aneurysms among endovascular therapists remains poorly defined. We performed a multireader study to determine what reader and patient variables contribute to this variation.

MATERIALS AND METHODS

Seven endovascular therapists (4 neuroradiologists, 3 neurosurgeons) independently reviewed 66 cases of patients treated with endovascular coil embolization for ruptured or unruptured aneurysm. Cases were rated on a 5-point scale recommending for whether to retreat and a recommended retreatment type. Reader agreement was assessed by intraclass correlation coefficient and by identifying cases with a "clinically meaningful difference" (a difference in score that would result in a difference in treatment). Variables that affect reader agreement and retreatment decisions were examined by using the Wilcoxon signed-rank test, Pearson χ(2) test, and linear regression.

RESULTS

Overall interobserver variability for decision to retreat was moderate (ICC = 0.50; 95% CI, 0.40-0.61). Clinically meaningful differences between at least 2 readers were present in 61% of cases and were significantly more common among neuroradiologists than neurosurgeons (P = .0007). Neurosurgeons were more likely to recommend "definitely retreat" than neuroradiologists (P < .0001). Previously ruptured aneurysms, larger remnant size, and younger patients were associated with more retreat recommendations. Interobserver variability regarding retreatment type was fair overall 0.25 (95% CI, 0.14-0.41) but poor for experienced readers 0.14 (95% CI, 0-0.34).

CONCLUSIONS

There is a large amount of interobserver variability regarding the decision to retreat an aneurysm and the type of retreatment. This variability must be reduced to increase consistency in these subjective outcome measurements.

Cervical spine MR imaging findings of patients with Hirayama disease in North America: a multisite study

BACKGROUND AND PURPOSE

Most studies of HD have been conducted in Asia, particularly Japan. To characterize the MR imaging findings of North American patients with HD, we reviewed neutral and flexion cervical MR imaging examinations performed for possible HD at 3 academic medical centers located in the Southeastern, Southwestern, and Midwestern regions of the United States.

MATERIALS AND METHODS

Three neuroradiologists assessed the MR imaging examinations in a blinded fashion and reached a consensus rating for LOA of the posterior dura to the spine, lower spinal cord atrophy, spinal cord T2 hyperintensity, loss of cervical lordosis, anterior dural shift with flexion, and confidence of imaging diagnosis. Final reference diagnosis was established separately with a retrospective chart review by a neurologist.

RESULTS

Twenty-one patients met the criteria for HD, all were North American males and all who reported their race were white. Seventeen patients did not meet the criteria and served as controls. Four imaging attributes, LOA, dural shift with flexion, consensus diagnosis of neutral images, and consensus diagnosis of combined neutral and flexion images were all able to discriminate the group with HD from the group without HD (P < .05 for each). Findings of HD were often present on neutral images, but the addition of flexion images increased diagnostic confidence.

CONCLUSIONS

MR imaging findings in white North American patients with HD include LOA on neutral images and forward displacement of the dura with flexion. Findings are often present on neutral MR images and, in the appropriate clinical scenario, should prompt flexion MR imaging to evaluate anterior dural shift.

Safety and efficacy of CT-guided transforaminal cervical epidural steroid injections using a posterior approach

BACKGROUND AND PURPOSE

Image-guided cervical transforaminal epidural injections play an important role in the management of cervical radicular pain syndromes. The safety and efficacy of these injections via an anterolateral approach has been well-studied. The goal of this retrospective review was to determine the safety and efficacy of CT-guided transforaminal epidural injections by using a posterior approach.

MATERIALS AND METHODS

Retrospective review of patient records was used to define VNPS and RMDI of patients undergoing CT-guided transforaminal cervical epidural injections between 2006 and 2010. Pain scores were recorded preprocedure, immediately postprocedure, at 2 weeks, and at 2 months. The RMDI was recorded preprocedure, at 2 weeks, and at 2 months. Data analysis of 247 patients was completed. Differences in VNPS scores and the RMDI were then compared on the basis of a CT-guided approach (anterolateral versus posterior).

RESULTS

There was no statistical difference in the degree of pain relief and improvement in the RMDI between the CT-guided transforaminal anterolateral approach and the posterior approach at 2 weeks and at 2 months. Both groups demonstrated a statistically significant improvement in pain scores and the RMDI. Approximately 35% of patients in both groups demonstrated >50% pain relief at 2 months. There were no serious complications in either group.

CONCLUSIONS

CT-guided transforaminal cervical epidural injections by using a posterior approach are safe and effective.

When should I do dynamic CT myelography? Predicting fast spinal CSF leaks in patients with spontaneous intracranial hypotension

BACKGROUND AND PURPOSE

Some patients with SIH have fast CSF leaks requiring dynamic CTM for localization; however, patients generally undergo conventional CTM before a dynamic study. Our aim was to determine whether findings on head MR imaging, spine MR imaging, or opening pressure measurements can predict fast spinal CSF leaks.

MATERIALS AND METHODS

A retrospective review was performed on 151 consecutive patients referred for CTM to evaluate for spinal CSF leak. Head MR imaging was evaluated for diffuse dural enhancement and "brain sag," and spine MR imaging for presence of an extradural fluid collection. The opening pressure was recorded. The CTM was scored as no leak, slow leak localized on conventional CTM, or fast leak that required dynamic CTM.

RESULTS

Fast CSF leaks were identified in 32 (21%), slow leaks in 36 (24%), and no leak in 83 (55%) of 151 patients on initial CTM. There was significant association between spinal extra-arachnoid fluid on MR imaging and the presence of a fast leak (sensitivity 85%, specificity 79%, P < .0001). There was not significant association between fast leak and findings on head MR imaging (P = .27) or opening pressure (P = .30).

CONCLUSIONS

If all patients with spinal extra-arachnoid CSF on MR imaging had been sent directly to dynamic CTM, repeat myelography would have been avoided in most patients with fast leaks (23 of 27; 85%). However, a minority of patients with slow or no leaks would have been converted from conventional to dynamic CTM (16 of 77; 21%). Spinal MR imaging is helpful in premyelographic evaluation of SIH.

Trafficking of yellow-fluorescent-protein-tagged mu1 subunit of clathrin adaptor AP-1 complex in living cells

Clathrin adaptor protein AP-1 complex is thought to function in forming clathrin-coated vesicles at the trans-Golgi network (TGN) and mediating transport of cargo between the TGN and endosomes. To study trafficking of AP-1 in living cells, yellow fluorescent protein (YFP) was inserted in the middle of mu1 A subunit of AP-1. When expressed in a tetracycline-dependent manner in HeLa cells, YFP-mu1 was efficiently incorporated into the AP-1 complex, replacing endogenous mu1 in most of cellular AP-1. Time-lapse imaging revealed that YFP-mu1/AP-1 departs from TGN as isolated vesicles and spherical structures, or varicosities, associated with fine tubular processes. Typically, several vesicles or varicosities were seen moving sequentially along the same 'tracks' from TGN to cell periphery. These data suggest that AP-1 may function after formation of Golgi transport intermediates in facilitating their intracellular movement. Mutagenesis of YFP-mu1 determined that the structural requirements for its binding to tyrosine-containing sequence motifs are similar to those previously defined in mu2 subunit of AP-2. Moreover, the carboxyl-terminal half of mu2 could replace the corresponding fragment of mu1 without loss of the ability of the resulting mu1-YFP-mu2 chimeric protein to incorporate into AP-1 and bind tyrosine-containing motifs. Mutations that abolish binding capacity for tyrosine motifs did not mistarget AP-1 in the cell, suggesting that AP-1 interactions with this type of sorting signals are not essential for membrane docking of AP-1 at the TGN. Altogether, this study demonstrates that YFP-tagged mu1 protein can serve as a useful tool for visualizing the dynamics of AP-1 in living cells and for the structure-function analysis of mu1-cargo interactions.

Vital capacity in tetraplegics twenty years and beyond

OBJECTIVES

To observe the trends in vital capacity (VC) over time in tetraplegics 20 years and more after injury, the effects of age at injury, severity of injury and gender on this trend.

METHODS

The medical records of all spinal cord injured persons admitted to a regional spinal injury center from January 1960 to December 1996 were reviewed. Fifty-seven patients had documented post-rehabilitation VC (mean 1.3+/-1.1 years) and VC at 10 (mean 11.8+/-2.69) and 20 (20.60+/-2.67) years post injury and beyond.

RESULTS

The mean age at injury was 23.2+/-9.1 years. Severity of injury when classified according the system proposed by Coll et al were: Group 1: C1-4 Frankel A injury: 11.6%, Group 2: C5-8 Frankel A injury: 55.6%, Group 3: C2-8 Frankel B and C: 29.8% and Group 4: C2-8 Frankel D: 3.5% respectively. The mean VC at initial, 10 and 20 years post injury was 2586+/-948, 2803+/-940 and 2525+/-818 cc respectively. Multivariate analysis of variance revealed that there was significant difference in VC over a 20 year period, (F(2,54)=8.43, P<0.05). The difference between VC at 10 years and VC at 20 years accounted for the 19.8% of the variance in VC over time (F(1,55)=12.35, P<0.05). Age at injury, gender and severity of injury did not have a significant influence on the rate of decline in VC. Analysis of a subset of 26 patients who were followed up more than 20 years post injury (range 22 to 34.5 years) revealed similar, with a greater drop in the VC from 10 years post injury (F(1,23)=6.52, P<0.05). In this subset of patients, the mean VC at initial injury was 2840.9+/-847.3 cc, at 10 years was 2549.6+/-750.3 cc, at 20 years was 2400.9+/-724.1 cc and beyond 20 years was 2194.2+/-738.7 cc. There was no significant difference in mean VC between non smokers and ex/current smokers at initial, 10 and 20 years post injury, using the independent t-test (P>0.05).

CONCLUSION

Vital capacity in tetraplegics declines significantly over the years, with a greater decline occurring at more than 20 years post injury.

Gain in functional ability during medical rehabilitation as related to rehabilitation process indices and neurologic measures

OBJECTIVE

To determine the incremental value of neurologic and rehabilitation process indices in predicting gain in functional abilities during rehabilitation after spinal cord injury (SCI) and to describe a model for program evaluation that provides unbiased comparisons of rehabilitation process and normative comparison of individual patient gains in functional ability.

STUDY DESIGN

Multiple regression including variables in a prespecified hierarchical fashion. Linear models are formulated to gauge the incremental value of neurologic measures and rehabilitation process indices when investigating the rehabilitation process and the outcome of medical rehabilitation.

RESULTS

All measures and indices vary in predictable and expected manners across individual centers and injury groups; moreover, each has demonstrated the capacity to provide unique information to the investigation of the rehabilitation process. The comprehensive set of variables accounts for 52.8% of the variance in self-care gain and 53.3% of the variance in mobility gain. The rehabilitation process indices together contribute 15% of the variance of self-care gain and over 18% of the explained variance in mobility gain.

CONCLUSION

Forecasting gain in functional ability of patients in the domains of self-care and mobility may be enhanced when measures of neurologic impairment are supplemented with rehabilitation process indices. In addition, technical enhancements in measurement of rehabilitation process indices and gain in functional ability provide objective comparison of individual center differences and individual patient gains.

Inhibition of the receptor-binding function of clathrin adaptor protein AP-2 by dominant-negative mutant mu2 subunit and its effects on endocytosis

Although interactions between the mu2 subunit of the clathrin adaptor protein complex AP-2 and tyrosine-based internalization motifs have been implicated in the selective recruitment of cargo molecules into coated pits, the functional significance of this interaction for endocytosis of many types of membrane proteins remains unclear. To analyze the function of mu2-receptor interactions, we constructed an epitope-tagged mu2 that incorporates into AP-2 and is targeted to coated pits. Mutational analysis revealed that Asp176 and Trp421 of mu2 are involved in the interaction with internalization motifs of TGN38 and epidermal growth factor (EGF) receptor. Inducible overexpression of mutant mu2, in which these two residues were changed to alanines, resulted in metabolic replacement of endogenous mu2 in AP-2 complexes and complete abrogation of AP-2 interaction with the tyrosine-based internalization motifs. As a consequence, endocytosis of the transferrin receptor was severely impaired. In contrast, internalization of the EGF receptor was not affected. These results demonstrate the potential usefulness of the dominant-interfering approach for functional analysis of the adaptor protein family, and indicate that clathrin-mediated endocytosis may proceed in both a mu2-dependent and -independent manner.

Endocytosis of functional epidermal growth factor receptor-green fluorescent protein chimera

A chimera of the epidermal growth factor receptor (EGFR) and green fluorescent protein (GFP) has been engineered by fusing GFP to the carboxyl terminus of EGFR. Data are provided to demonstrate that the GFP moiety does not affect the expected functioning of EGFR. EGFR-GFP becomes phosphorylated at tyrosine residues in response to EGF and is capable of phosphorylating endogenous substrates and initiating signaling cascades. EGF-dependent association of the chimeric receptor with the clathrin adaptor protein AP-2, involved in endocytosis, and with Shc adaptor protein, which binds in close proximity to the fusion point, is not affected by the GFP moiety. Receptor down-regulation and internalization occur at rates similar to those in cells expressing wild-type EGFR. Western blot analysis reveals that lysosomal degradation of EGFR-GFP proceeds from the extracellular domain and that GFP is not preferentially cleaved. Time-dependent co-localization of EGFR-GFP and Texas Red-conjugated EGF in living cells using digital deconvolution microscopy demonstrates the trafficking of ligand-receptor complexes through the early and multivesicular endosomes followed by segregation of the ligand and receptor at the late stages of endocytosis. Time-lapse optical analysis of the early stages of endocytosis reveals localization of EGFR-GFP in the tubular-vesicular endosomal compartments. Rapid dynamics of membrane movement and fusion within these compartments were observed. This approach and the fidelity of the biochemical properties of the EGFR-GFP demonstrate that real-time visualization of trafficking and protein interactions of tyrosine kinase receptors in the presence or absence of the ligand are feasible.

Structure and Asn-Pro-Phe binding pocket of the Eps15 homology domain

Eps15 homology (EH) domains are eukaryotic signaling modules that recognize proteins containing Asn-Pro-Phe (NPF) sequences. The structure of the central EH domain of Eps15 has been solved by heteronuclear magnetic resonance spectroscopy. The fold consists of a pair of EF hand motifs, the second of which binds tightly to calcium. The NPF peptide is bound in a hydrophobic pocket between two alpha helices, and binding is mediated by a critical aromatic interaction as revealed by structure-based mutagenesis. The fold is predicted to be highly conserved among 30 identified EH domains and provides a structural basis for defining EH-mediated events in protein trafficking and growth factor signaling.

Eps15 is constitutively oligomerized due to homophilic interaction of its coiled-coil region

Eps15 is a member of an emerging family of proteins containing a novel protein/protein interaction domain, the EH domain, of as yet unknown function. Recent findings of Eps15 association with clathrin adaptor complex AP-2 and its localization in clathrin-coated pits have implicated Eps15 in the regulation of vesicle trafficking. Here we show that Eps15 exists in several multimeric states in vivo. When purified recombinant Eps15 or lysates of NIH 3T3 cells were treated with cross-linking reagents, covalent dimers of Eps15 and larger covalent multimers were detected in high yield. Large Eps15 oligomers co-immunoprecipitated with AP-2 at an efficiency higher than that of Eps15 dimers. Furthermore, cross-linking of the membrane-bound fraction of Eps15 in mildly permeabilized cells was as efficient as that of the cytosolic fraction. Size-exclusion column chromatography of recombinantly produced Eps15 and of total cell lysates was performed to examine the equilibrium ratio of the monomers versus the aggregated forms of Eps15. These experiments showed that essentially all the Eps15 was aggregated, whereas monomers of Eps15 could be obtained only under strong denaturing conditions. To map the region of Eps15 responsible for dimerization, fusion proteins corresponding to the three structural domains of Eps15 were prepared. Cross-linking analysis revealed that the central portion of Eps15, which possesses a coiled-coil region (residues 321-520), serves as the interacting interface. The possibility that hetero-oligomeric complexes of Eps15 dimers and AP-2 function during the recruitment of proteins into coated pits is discussed.

N-acetylaspartylglutamate, N-acetylaspartate, and N-acetylated alpha-linked acidic dipeptidase in human brain and their alterations in Huntington and Alzheimer's diseases

There is mounting evidence, primarily from research in experimental animals, that the dipeptide N-acetylaspartylglutamate (NAAG) and its metabolic enzyme, N-acetylated alpha-linked acid dipeptidase (NAALADase), are involved in glutamatergic neurotransmission. Previous studies in neuropsychiatric disorders associated with the dysregulation of glutamatergic neurotransmission, such as schizophrenia, seizure disorders, and amyotrophic lateral sclerosis (ALS), have revealed region-specific alterations in the levels of NAAG and in the activity of NAALADase. To establish better the cellular localization of these and related parameters in human brain, we have examined their alterations in two well-characterized selective neurodengenerative disorders, Huntington Disease (HD) and Alzheimer Disease (AD). Brain regions from postmortem controls and HD- or AD-affected individuals were assayed to determine the activity of NAALADase as well as the levels of NAAG, N-acetylaspartate (NAA), and several amino acids. The relationships between changes in these neurochemical parameters and changes in neuronal and glial cell density were determined. The present report demonstrates that the decreases in the levels of NAAG and NAA and in the activity of NAALADase in AD and HD brain correlate primarily with neuronal loss. By inference, the results suggest that NAAG and NAA have primarily a neuronal localization in human brain and that there is a close relationship between NAAG and the dipeptidase NAALADase in populations of affected neurons.

Clonal structure of the introduced freshwater snailPotamopyrgus antipodarum(Prosobranchia: Hydrobiidae), as revealed by DNA fingerprinting

Multi-locus DNA fingerprints were obtained from individuals of the hydrobiid snail, Potamopyrgus antipodarum (= P. jenkinsi), by using an RNA derivative (pSPT 18.15) of Jeffrey's 33.15 minisatellite core sequence. Whole-body homogenization of snails yielded 3.21 +/- 0.09 micrograms DNA per individual, producing complex profiles comprising 12-22 fragments within the 1.0-20.0 kilobase (kb) size range. Fingerprints from natural and experimental populations identified three distinct clonal genotypes corresponding to morphological strains A, B and C, with only rare mutational variants. Mother-offspring comparisons of genetic fingerprints revealed genetic stability during apomictic parthenogenesis. Data support the notion that British populations of P. antipodarum comprise three widespread obligate parthenogenetic clones resulting from a mid-19th Century introduction from Australasia. The present-day low levels of genotypic diversity are discussed in relation to the typical occurrence of P. antipodarum in man-made or immature habitats.

Prostate-specific membrane antigen is a hydrolase with substrate and pharmacologic characteristics of a neuropeptidase

This report demonstrates that the investigational prostatic carcinoma marker known as the prostate-specific membrane antigen (PSM) possesses hydrolytic activity with the substrate and pharmacologic properties of the N-acetylated alpha-linked acidic dipeptidase (NAALADase). NAALADase is a membrane hydrolase that has been characterized in the mammalian nervous system on the basis of its catabolism of the neuropeptide N-acetylaspartylglutamate (NAAG) to yield glutamate and N-acetylaspartate and that has been hypothesized to influence glutamatergic signaling processes. The immunoscreening of a rat brain cDNA expression library with anti-NAALADase antisera identified a 1428-base partial cDNA that shares 86% sequence identity with 1428 bases of the human PSM cDNA [Israeli, R. S., Powell, C. T., Fair, W. R. & Heston, W.D.W. (1993) Cancer Res. 53, 227-230]. A cDNA containing the entire PSM open reading frame was subsequently isolated by reverse transcription-PCR from the PSM-positive prostate carcinoma cell line LNCaP. Transient transfection of this cDNA into two NAALADase-negative cell lines conferred NAAG-hydrolyzing activity that was inhibited by the NAALADase inhibitors quisqualic acid and beta-NAAG. Thus we demonstrate a PSM-encoded function and identify a NAALADase-encoding cDNA. Northern analyses identify at least six transcripts that are variably expressed in NAALADase-positive but not in NAALADase-negative rat tissues and human cell lines; therefore, PSM and/or related molecular species appear to account for NAAG hydrolysis in the nervous system. These results also raise questions about the role of PSM in both normal and pathologic prostate epithelial-cell function.

The gene for the serpin thrombin inhibitor (PI7), protease nexin I, is located on human chromosome 2q33-q35 and on syntenic regions in the mouse and sheep genomes

Protease nexin I (PNI) is the most important physiologic regulator of alpha-thrombin in tissues. PNI is highly expressed and developmentally regulated in the nervous system where it is concentrated at neuromuscular junctions and also central synapses in the hippocampus and striatum. Approximately 10% of identified proteins at mammalian neuromuscular junctions are serine protease inhibitors, consistent with their central role in balancing serine protease activity to develop, maintain, and remodel synapses. Southern blot hybridization of PNI cDNA to somatic cell hybrids placed the structural gene for PNI (locus PI7) on human chromosome 2q33-q35 and to syntenic chromosomes in the mouse (chromosome 1) and sheep (chromosome 2).

The immunocytochemical localization of N-acetylaspartyl glutamate, its hydrolysing enzyme NAALADase, and the NMDAR-1 receptor at a vertebrate neuromuscular junction

Although glutamate is thought to be the neurotransmitter at the invertebrate neuromuscular junction, acetylcholine is accepted as the primary neurotransmitter of the vertebrate motoneurons. N-acetylaspartylglutamate, a dipeptide localized in putative glutamatergic neurons in brain, is also found in high concentrations (> mM) in mammalian motoneurons and the ventral roots of spinal cord. N-acetylaspartylglutamate, which is released from neurons by depolarization in a Ca(2+)-dependent fashion, is implicated in glutamatergic transmission in two ways: it is a partial agonist at NMDA receptors, and it is cleaved to yield extracellular glutamate and N-acetylasparate by the specific peptidase N-acetylated alpha-linked acidic dipeptidase. Given the localization of N-acetylaspartylglutamate in motor neuronal perikarya and axons, we wondered whether N-acetylaspartylglutamate or glutamate cleaved from N-acetylaspartylglutamate by N-acetylated alpha-linked acidic dipeptidase may also play a role in neuromuscular transmission. Here we describe the immunocytochemical detection at the rat neuromuscular junction of N-acetylaspartylglutamate in terminals of motoneurons, of N-acetylated alpha-linked acidic dipeptidase in perisynaptic Schwann cells, and of the NMDAR-1 glutamate receptor subunit on postsynaptic muscle membranes. These results point to a potential role for N-acetylaspartylglutamate at the rat neuromuscular junction. Further, this is the first demonstration of a glutamate receptor protein at vertebrate neuromuscular synapses. Together with other recent findings, our results suggest that glutamate-like molecules are involved in neuromuscular transmission not only in invertebrates but also in veretebrates where they may modulate signaling by acetylcholine.

N-acetylated alpha-linked acidic dipeptidase is expressed by non-myelinating Schwann cells in the peripheral nervous system

N-acetylated alpha-linked acidic dipeptidase is a membrane-bound brain peptidase which cleaves the neuropeptide N-acetyl-aspartyl-glutamate to N-acetyl-aspartate and glutamate. In the present study, we have determined the localization of N-acetylated alpha-linked acidic dipeptidase in the peripheral nervous system. Using enzyme assays and immunoblotting, we demonstrate that sciatic nerve, phrenic nerve, cervical dorsal root ganglion and superior cervical ganglion contain N-acetylated alpha-linked acidic dipeptidase activity as well as an N-acetylated alpha-linked acidic dipeptidase-like protein. Furthermore, we show that N-acetylated alpha-linked acidic dipeptidase-like immunoreactivity is extensively co-localized in peripheral nerves with immunoreactivity for glial fibrillary acidic protein, a known marker for non-myelinating Schwann cells. Using electron microscopy, we demonstrate N-acetylated alpha-linked acidic dipeptidase-like immunoreactivity in cell membranes of non-myelinating Schwann cells in the superior cervical ganglion. These results show that N-acetylated alpha-linked acidic dipeptidase is expressed in the peripheral nervous system by non-myelinating Schwann cells. This cellular localization suggests that N-acetylated alpha-linked acidic dipeptidase may be involved in the signalling between axons and Schwann cells, for example during development or regeneration.

No evidence for extrapair fertilizations in the merlin revealed by DNA fingerprinting

Broods of young merlins were compared with the adults in attendance at their nest by DNA fingerprinting. No offspring were found that mismatched genetically suggesting that intraspecific brood parasitism and extrapair fertilization are very rare in this population. The results are discussed in the light of the Paternity Assurance Hypothesis.

Genetic-Evidence for Extra-Pair Fertilizations in Socially Monogamous Short-Tailed Shearwaters, Puffinus-Tenuirostris (Procellariiformes, Procellariidae), Using Dna Fingerprinting

Genetic relationships between adults and nestlings of the short-failed shearwater, Puffinus tenuirostris, were analysed by multilocus DNA fingerprinting. Short-tailed shearwaters are socially monogamous, forming strong pair bonds, often for many years. The human polycore minisatellite probe, 33-6, revealed sufficient variation in shearwater DNA to allow individual-specific identification. A total of 22 nestlings and 32 adults, comprising 10 trios of nestling and both parents, and 12 pairs of nestling and only one parent, were examined. Analysis of fingerprint profiles revealed four cases where a nestling was not related to one of the attendant adults, and may have resulted from an extra-pair fertilisation. Extra-pair fertilisations, as an alternative breeding strategy, are discussed with respect to the biased and low reproductive output of this long-lived species.

Genetically epilepsy-prone rats have increased brain regional activity of an enzyme which liberates glutamate from N-acetyl-aspartyl-glutamate

N-Acetylated-alpha-linked acidic dipeptidase (NAALADase) is a membrane-bound peptidase which hydrolyzes the endogenous neuropeptide N-acetylaspartylglutamate (NAAG) to N-acetylaspartate (NAA) and the excitatory amino acid, glutamate (Glu). Although there is evidence that NAAG might be a neurotransmitter, this dipeptide could also function as a precursor form of Glu, which is liberated by the dipeptidase. We found that the activity of this NAAG hydrolyzing enzyme in genetically epilepsy-prone rats was 11-26% greater than control in brain regions, including the amygdala, hippocampus and cerebellum, as well as the pyriform, entorhinal and frontal cortices. This is consistent with possible increased availability of Glu in certain CNS synapses in these rats, which are reported to have increased susceptibility to audiogenically, electrically and chemically induced convulsions.

Criteria for the academic promotion of medical school-based psychiatrists

The objective of this study was to identify criteria used in recommending faculty for promotion in medical school-based departments of psychiatry. Chairs of 125 departments in the United States were asked to complete a 39-item questionnaire on departmental demographics and the expectations for academic performance of tenure-track, non-tenure-track, part-time, and medical research faculty. Different criteria were reported for the classifications of faculty studied, but not for promotion of the same class of faculty to different academic ranks. The increasing need for faculty to generate revenue blurs the distinction between tenure-track and non-tenure-track faculty and calls into question whether tenure track can practically continue as a faculty classification.

Residency training and the later use of marital and family therapy in psychiatric practice

Marital and family therapy training during psychiatry residency was compared to later use, in practice, for 87 psychiatrists. Respondents reported modest to minimal amounts of training in residency but practiced marital and family therapy with a variety of problems, identified a spread of effect to other treatment modalities, and preferred marital and family therapy second only to individual therapy. These results suggest a trend towards incorporating marital and family therapy into psychiatry and also indicate levels of training which must be exceeded in order to achieve basic competency.

Improved genetic fingerprinting using RNA probes

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Clonidine effect on spasticity: a clinical trial

Clonidine was used as an adjunct to baclofen in 55 patients with spasticity due to spinal cord injury. Dosage was held at the minimum effect amount for those who responded. No effect was seen in 24 patients (44%), although 31 (56%) benefitted from the drug. Patients were grouped as quadriplegics or paraplegics, having complete or incomplete lesions. Of all quadriplegics, seven of 11 complete (64%) and 17 of 25 incomplete patients (68%) responded; among the paraplegics, six of 15 complete (40%) and one of four incomplete patients (25%) improved. Side effects were limited to postural hypotension necessitating reduction in dosage in three patients that were successfully treated; in the unsuccessfully treated group, one patient had insomnia, one had dizziness, and one had drowsiness.

Profile of denials of durable medical equipment for SCI patients by third party payers

The difficulty in obtaining approval for payment of durable medical equipment by third party payers has impeded the rehabilitation program and discharge planning of many spinal cord patients throughout the country for many years. To gain some insight as to the number and level of patients affected, the kinds of equipment denied, the reasons given for the denial, which third party payers were mostly involved and how the patient and his/her family managed to cope or resolve this problem, a survey was undertaken. Letters were sent to 259 members of the American Spinal Injury Association (ASIA) asking them to list representative cases where requests for equipment deemed necessary were denied. Twenty-eight responses from different institutions were received from sixteen states describing 110 patients and 180 pieces of durable medical equipment denied in 1984 and 1985. Manual wheelchairs, motorized wheelchairs, shower/commode chairs, and environmental control units were the four most common equipment items denied by the third party payers. Government agencies ie., Medicaid, Medicare, Vocational Rehabilitation Departments and State Crippled Children's Services were the most frequent deniers, comprising 54% of the total sample. They were followed by private insurance (31%) and Workman's Compensation (3%). By far, the two most common reasons given for denials were: it was not covered by the insurance policy (38%) and it was not medically necessary (30%). Ninety (90) pieces of equipment (50%) were eventually obtained, most often by charity, or through the patient's family resources.

Ultrasonography of the shoulder. Static and dynamic imaging

High-resolution, real-time ultrasonography is an effective diagnostic technique for evaluating rotator cuff movements and is useful in detecting aberrations that correlate with rotator cuff biomechanics and impingement syndrome.

Structure-activity relationships for unsaturated dialdehydes. 1. The mutagenic activity of 18 compounds in the Salmonella/microsome assay

A considerable number of terpenes that contain an "unsaturated dialdehyde" functionality, and possess various biological activities, such as antimicrobial activity, pungency, antifeedant activity, and/or mutagenicity, have been isolated from natural sources. However, large qualitative and quantitative activity differences have been observed for the natural unsaturated dialdehydes, and small structural changes (e.g., stereoisomerization) seem to dramatically affect the biological activity. As part of a general attempt to study structure-activity relationships for unsaturated dialdehydes, the activity of compounds 1-18 (Table 1) in the Salmonella/microsome assay (strains TA98, TA2637 and TA100) has been investigated. 10 of the compounds were found to possess direct-acting mutagenic activity, although the mutagenic potencies vary considerably in this group (from 430 to 0.32 revertants per nmole in the Salmonella strain TA2637). Some structural features that appear to moderate the activity are discussed. The necessity of an intact unsaturated dialdehyde functionality for the mutagenic activity of isovelleral (1) (see Scheme 1 for names, numbers, and chemical structures) in the Salmonella/microsome assay was demonstrated by chemical conversions: modification of either aldehyde group or reduction of the double bond led to loss of activity.