ULTRA-SR Challenge: Assessment of Ultrasound Localization and TRacking Algorithms for Super-Resolution Imaging

With the widespread interest and uptake of super-resolution ultrasound (SRUS) through localization and tracking of microbubbles, also known as ultrasound localization microscopy (ULM), many localization and tracking algorithms have been developed. ULM can image many centimeters into tissue in-vivo and track microvascular flow non-invasively with sub-diffraction resolution. In a significant community effort, we organized a challenge, Ultrasound Localization and TRacking Algorithms for Super-Resolution (ULTRA-SR). The aims of this paper are threefold: to describe the challenge organization, data generation, and winning algorithms; to present the metrics and methods for evaluating challenge entrants; and to report results and findings of the evaluation. Realistic ultrasound datasets containing microvascular flow for different clinical ultrasound frequencies were simulated, using vascular flow physics, acoustic field simulation and nonlinear bubble dynamics simulation. Based on these datasets, 38 submissions from 24 research groups were evaluated against ground truth using an evaluation framework with six metrics, three for localization and three for tracking. In-vivo mouse brain and human lymph node data were also provided, and performance assessed by an expert panel. Winning algorithms are described and discussed. The publicly available data with ground truth and the defined metrics for both localization and tracking present a valuable resource for researchers to benchmark algorithms and software, identify optimized methods/software for their data, and provide insight into the current limits of the field. In conclusion, Ultra-SR challenge has provided benchmarking data and tools as well as direct comparison and insights for a number of the state-of-the art localization and tracking algorithms.

Acoustic diffraction-resistant adaptive profile technology (ADAPT) for elasticity imaging

Acoustic beam shaping with high degrees of freedom is critical for applications such as ultrasound imaging, acoustic manipulation, and stimulation. However, the ability to fully control the acoustic pressure profile over its propagation path has not yet been achieved. Here, we demonstrate an acoustic diffraction-resistant adaptive profile technology (ADAPT) that can generate a propagation-invariant beam with an arbitrarily desired profile. By leveraging wave number modulation and beam multiplexing, we develop a general framework for creating a highly flexible acoustic beam with a linear array ultrasonic transducer. The designed acoustic beam can also maintain the beam profile in lossy material by compensating for attenuation. We show that shear wave elasticity imaging is an important modality that can benefit from ADAPT for evaluating tissue mechanical properties. Together, ADAPT overcomes the existing limitation of acoustic beam shaping and can be applied to various fields, such as medicine, biology, and material science.

The Future Is Beyond Bright: The Evolving Role of Quantitative US for Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a common cause of morbidity and mortality. Nonfocal liver biopsy is the historical reference standard for evaluating NAFLD, but it is limited by invasiveness, high cost, and sampling error. Imaging methods are ideally situated to provide quantifiable results and rule out other anatomic diseases of the liver. MRI and US have shown great promise for the noninvasive evaluation of NAFLD. US is particularly well suited to address the population-level problem of NAFLD because it is lower-cost, more available, and more tolerable to a broader range of patients than MRI. Noninvasive US methods to evaluate liver fibrosis are widely available, and US-based tools to evaluate steatosis and inflammation are gaining traction. US techniques including shear-wave elastography, Doppler spectral imaging, attenuation coefficient, hepatorenal index, speed of sound, and backscatter-based estimation have regulatory clearance and are in clinical use. New methods based on channel and radiofrequency data analysis approaches have shown promise but are mostly experimental. This review discusses the advantages and limitations of clinically available and experimental approaches to sonographic liver tissue characterization for NAFLD diagnosis as well as future applications and strategies to overcome current limitations.

Ultrasonic Sound Speed Estimation for Liver Fat Quantification: A Review by the AIUM-RSNA QIBA Pulse-Echo Quantitative Ultrasound Initiative

Non-alcoholic fatty liver disease (NAFLD) is a significant cause of diffuse liver disease, morbidity and mortality worldwide. Early and accurate diagnosis of NALFD is critical to identify patients at risk of disease progression. Liver biopsy is the current gold standard for diagnosis and prognosis. However, a non-invasive diagnostic tool is desired because of the high cost and risk of complications of tissue sampling. Medical ultrasound is a safe, inexpensive and widely available imaging tool for diagnosing NAFLD. Emerging sonographic tools to quantitatively estimate hepatic fat fraction, such as tissue sound speed estimation, are likely to improve diagnostic accuracy, precision and reproducibility compared with existing qualitative and semi-quantitative techniques. Various pulse-echo ultrasound speed of sound estimation methodologies have been investigated, and some have been recently commercialized. We review state-of-the-art in vivo speed of sound estimation techniques, including their advantages, limitations, technical sources of variability, biological confounders and existing commercial implementations. We report the expected range of hepatic speed of sound as a function of liver steatosis and fibrosis that may be encountered in clinical practice. Ongoing efforts seek to quantify sound speed measurement accuracy and precision to inform threshold development around meaningful differences in fat fraction and between sequential measurements.

Memory-efficient low-compute segmentation algorithms for bladder-monitoring smart ultrasound devices

Post-operative urinary retention is a medical condition where patients cannot urinate despite having a full bladder. Ultrasound imaging of the bladder is used to estimate urine volume for early diagnosis and management of urine retention. Moreover, the use of bladder ultrasound can reduce the need for an indwelling urinary catheter and the risk of catheter-associated urinary tract infection. Wearable ultrasound devices combined with machine-learning based bladder volume estimation algorithms reduce the burdens of nurses in hospital settings and improve outpatient care. However, existing algorithms are memory and computation intensive, thereby demanding the use of expensive GPUs. In this paper, we develop and validate a low-compute memory-efficient deep learning model for accurate bladder region segmentation and urine volume calculation. B-mode ultrasound bladder images of 360 patients were divided into training and validation sets; another 74 patients were used as the test dataset. Our 1-bit quantized models with 4-bits and 6-bits skip connections achieved an accuracy within [Formula: see text] and [Formula: see text], respectively, of a full precision state-of-the-art neural network (NN) without any floating-point operations and with an [Formula: see text] and [Formula: see text] reduction in memory requirements to fit under 150 kB. The means and standard deviations of the volume estimation errors, relative to estimates from ground-truth clinician annotations, were [Formula: see text] ml and [Formula: see text] ml, respectively. This lightweight NN can be easily integrated on the wearable ultrasound device for automated and continuous monitoring of urine volume. Our approach can potentially be extended to other clinical applications, such as monitoring blood pressure and fetal heart rate.

Individualized Ultrasound-Guided Intervention Phantom Development, Fabrication, and Proof of Concept

Commercial ultrasound vascular phantoms lack the anatomic diversity required for robust pre-clinical interventional device testing. We fabricated individualized phantoms to test an artificial intelligence enabled ultrasound-guided surgical robotic system (AI-GUIDE) which allows novices to cannulate deep vessels. After segmenting vessels on computed tomography scans, vessel cores, bony anatomy, and a mold tailored to the skin contour were 3D-printed. Vessel cores were coated in silicone, surrounded in tissue-mimicking gel tailored for ultrasound and needle insertion, and dissolved with water. One upper arm and four inguinal phantoms were constructed. Operators used AI-GUIDE to deploy needles into phantom vessels. Two groin phantoms were tested due to imaging artifacts in the other two phantoms. Six operators (medical experience: none, 3; 1-5 years, 2; 5+ years, 1) inserted 27 inguinal needles with 81% (22/27) success in a median of 48 seconds. Seven operators performed 24 arm injections, without tuning the AI for arm anatomy, with 71% (17/24) success. After excluding failures due to motor malfunction and a defective needle, success rate was 100% (22/22) in the groin and 85% (17/20) in the arm. Individualized 3D-printed phantoms permit testing of surgical robotics across a large number of operators and different anatomic sites. AI-GUIDE operators rapidly and reliably inserted a needle into target vessels in the upper arm and groin, even without prior medical training. Virtual device trials in individualized 3-D printed phantoms may improve rigor of results and expedite translation.Clinical Relevance- Individualized phantoms enable rigorous and efficient evaluation of interventional devices and reduce the need for animal and human subject testing.

Spatially targeted brain cancer immunotherapy with closed-loop controlled focused ultrasound and immune checkpoint blockade

Despite the challenges in treating glioblastomas (GBMs) with immune adjuvants, increasing evidence suggests that targeting the immune cells within the tumor microenvironment (TME) can lead to improved responses. Here, we present a closed-loop controlled, microbubble-enhanced focused ultrasound (MB-FUS) system and test its abilities to safely and effectively treat GBMs using immune checkpoint blockade. The proposed system can fine-tune the exposure settings to promote MB acoustic emission-dependent expression of the proinflammatory marker ICAM-1 and delivery of anti-PD1 in a mouse model of GBM. In addition to enhanced interaction of proinflammatory macrophages within the PD1-expressing TME and significant improvement in survival (P < 0.05), the combined treatment induced long-lived memory T cell formation within the brain that supported tumor rejection in rechallenge experiments. Collectively, our findings demonstrate the ability of MB-FUS to augment the therapeutic impact of immune checkpoint blockade in GBMs and reinforce the notion of spatially tumor-targeted (loco-regional) brain cancer immunotherapy.

Esophageal safety in CLOSE-guided 50W high-power-short-duration pulmonary vein isolation - The PREHEAT-PVI-Registry

AIMS

Pulmonary vein isolation (PVI) using high-power-short-duration (HPSD) radiofrequency ablation (RF) is emerging as the standard of care for treatment of atrial fibrillation (AF). While procedural short-term to mid-term efficacy and efficiency are very promising, this registry aims to investigate esopahgeal safety using an optimized ablation approach.

METHODS

In a single-centre experience, 388 consecutive standardized first-time AF ablation were performed using a CLOSE-guided-fixed-50W-circumferential PVI and substrate modification without intraprocedural oesophageal temperature measurement. 300 patients underwent post-procedural esophageal endoscopy to diagnose and grade endoscopically detected esophageal lesions (EDEL) and were included in the analysis.

RESULTS

EDEL were detected in 35 of 300 patients (11.6%), 25 of 35 were low-grade KCC 1 lesions with fast healing tendencies. 6 patients suffered KCC 2a lesions, 4 patients had KCC 2b lesions (1.3% of all patients). No esophageal perforation or fistula formation was observed. Patient baseline characteristics, especially patients age, gender and body-mass-index did not influence EDEL incidence. Additional posterior box isolation did not increase the incidence of EDEL. In patients diagnosed with EDEL, mean catheter contact force during posterior wall ablation was higher (11.9 ± 1.8 vs. 14.7 ± 3 grams, p<0.001), mean RF duration was shorter (11.9 ± 1 vs. 10.7 ± 1.2 sec., p<0.001), while achieved AI was not different between groups (434 ± 4.9 vs. 433 ± 9.5, n.s.).

CONCLUSIONS

Incidence of EDEL after CLOSE-guided-50W-HPSD PVI is lower compared to historical cohorts using standard-power RF settings. Catheter contact force during posterior HPSD ablation should not exceed 15 grams. This article is protected by copyright. All rights reserved.

Spinal surgery for gallstones disease - Case report of a rare differential diagnosis

INTRODUCTION AND IMPORTANCE

Abdominal pain in the right upper quadrant is very common for patients to present in the emergency department. Finding the correct diagnosis seems straightforward in most cases but can be challenging.

CASE PRESENTATION

We present the case of a 75-year-old male with a rare differential diagnosis for right upper quadrant and back pain, initially diagnosed as symptomatic cholelithiasis. After referral to an abdominal surgeon, detailed history taking prior to planned cholecystectomy revealed a record of back pain due to spinal degeneration and fusion surgery, as well as a bulb of the right abdominal wall with hypesthesia in a dermatomal area in the right upper quadrant. Considering these "new" facts, a spinal surgeon was consulted and a foraminal disc hernia of the thoracic vertebrae 11/12 was identified as the cause of symptoms. Instead of the initially planned cholecystectomy, a right-sided facetectomy Th11/12, sequestrectomy and unilateral transpedicular stabilization to decompress the nerve root was successfully performed.

CLINICAL DISCUSSION

Although, symptomatic cholelithiasis is one of the most common diagnoses for patients presenting with right upper quadrant pain in the presence of gallstones, other differential diagnoses have to be considered. Thoracic disc herniations can present with atypical symptoms that mimic other non-spinal causes and may pose a diagnostic challenge, sometimes even leading to unnecessary surgery.

CONCLUSION

This case highlights a rare differential diagnosis for one of the most common diseases seen by emergency physicians. It emphasizes the risk of working under time pressure, especially in an emergency setting, which may lead to premature diagnostic error and treatment, endangering patient's care and safety.

Reconnection patterns after high-power-short-duration pulmonary vein isolation Reconnection patterns after CLOSE-guided 50W high-power-short-duration circumferential pulmonary vein isolation and substrate modification - PV reconnection might no longer be an issue

INTRODUCTION

Ablation of atrial fibrillation (AF) with high-power-short-duration (HPSD) radiofrequency (RF) technology is emerging as a new standard of care in many electrophysiology laboratories. While procedural short-term efficacy and efficiency is very promising, little is known about mid- to long-term effects of HPSD ablation for pulmonary vein isolation and left atrial substrate modification.

METHODS AND RESULTS

In a single-centre registry, 412 AF procedures were performed in 400 individual patients using a standardized CLOSE protocol guided fixed 50W HPSD ablation, aiming for an ablation index (AI) of 400 on the posterior and 550 on the anterior wall. Additional substrate-tailored lines were performed when required. After a mean clinical follow-up of 337 ± 134 days, 15 patients suffered from AF recurrence beyond the blinding period. 12 gave consent to the indicated re-ablation. Here, 11 of 12 patients had chronic isolation of all 4 pulmonary veins (PV). In 3 of 6 patients, a reconnection of additional left atrial ablation lines was revealed. 10 out of 12 patients showed progressive fibrous atrial cardiomyopathy and required additional left atrial substrate modification or re-isolation of left-atrial lines. During the follow-up no clinical case of atrioesophageal fistula was registered. No PV stenosis after initial HPSD PVI was documented.

CONCLUSIONS

Patients requiring re-ablation of AF or other atrial tachycardia after a fixed 50W HPSD circumferential PVI and substrate modification predominantly suffer from progressive fibrous atrial cardiomyopathy, while PV reconnection appears to be a rare cause of AF recurrence. This article is protected by copyright. All rights reserved.

Experimental Demonstration of Trans-Skull Volumetric Passive Acoustic Mapping With the Heterogeneous Angular Spectrum Approach

Real-time, 3-D, passive acoustic mapping (PAM) of microbubble dynamics during transcranial focused ultrasound (FUS) is essential for optimal treatment outcomes. The angular spectrum approach (ASA) potentially offers a very efficient method to perform PAM, as it can reconstruct specific frequency bands pertinent to microbubble dynamics and may be extended to correct aberrations caused by the skull. Here, we experimentally assess the abilities of heterogeneous ASA (HASA) to perform trans-skull PAM. Our experimental investigations demonstrate that the 3-D PAMs of a known 1-MHz source, constructed with HASA through an ex vivo human skull segment, reduced both the localization error (from 4.7 ± 2.3 to 2.3 ± 1.6 mm) and the number, size, and energy of spurious lobes caused by aberration, with the modest additional computational expense. While further improvements in the localization errors are expected with arrays with denser elements and larger aperture, our analysis revealed that experimental constraints associated with the array pitch and aperture (here, 1.8 mm and 2.5 cm, respectively) can be ameliorated by interpolation and peak finding techniques. Beyond the array characteristics, our analysis also indicated that errors in the registration (translation and rotation of ±5 mm and ±5°, respectively) of the skull segment to the array can lead to peak localization errors of the order of a few wavelengths. Interestingly, errors in the spatially dependent speed of sound in the skull (±20%) caused only subwavelength errors in the reconstructions, suggesting that registration is the most important determinant of point source localization accuracy. Collectively, our findings show that HASA can address source localization problems through the skull efficiently and accurately under realistic conditions, thereby creating unique opportunities for imaging and controlling the microbubble dynamics in the brain.

Towards controlled drug delivery in brain tumors with microbubble-enhanced focused ultrasound

Brain tumors are particularly challenging malignancies, due to their location in a structurally and functionally distinct part of the human body - the central nervous system (CNS). The CNS is separated and protected by a unique system of brain and blood vessel cells which together prevent most bloodborne therapeutics from entering the brain tumor microenvironment (TME). Recently, great strides have been made through microbubble (MB) ultrasound contrast agents in conjunction with ultrasound energy to locally increase the permeability of brain vessels and modulate the brain TME. As we elaborate in this review, this physical method can effectively deliver a wide range of anticancer agents, including chemotherapeutics, antibodies, and nanoparticle drug conjugates across a range of preclinical brain tumors, including high grade glioma (glioblastoma), diffuse intrinsic pontine gliomas, and brain metastasis. Moreover, recent evidence suggests that this technology can promote the effective delivery of novel immunotherapeutic agents, including immune check-point inhibitors and chimeric antigen receptor T cells, among others. With early clinical studies demonstrating safety, and several Phase I/II trials testing the preclinical findings underway, this technology is making firm steps towards shaping the future treatments of primary and metastatic brain cancer. By elaborating on its key components, including ultrasound systems and MB technology, along with methods for closed-loop spatial and temporal control of MB activity, we highlight how this technology can be tuned to enable new, personalized treatment strategies for primary brain malignancies and brain metastases.

Morphological Reconstruction Improves Microvessel Mapping in Super-Resolution Ultrasound

Generation of super-resolution (SR) ultrasound (US) images, created from the successive localization of individual microbubbles in the circulation, has enabled the visualization of microvascular structure and flow at a level of detail that was not possible previously. Despite rapid progress, tradeoffs between spatial and temporal resolution may challenge the translation of this promising technology to the clinic. To temper these tradeoffs, we propose a method based on morphological image reconstruction. This method can extract from ultrafast contrast-enhanced US (CEUS) images hundreds of microbubble peaks per image (312-by-180 pixels) with intensity values varying by an order of magnitude. Specifically, it offers a fourfold increase in the number of peaks detected per frame, requires on the order of 100 ms for processing, and is robust to additive electronic noise (down to 3.6-dB CNR in CEUS images). By integrating this method to an SR framework, we demonstrate a sixfold improvement in spatial resolution, when compared with CEUS, in imaging chicken embryo microvessels. This method that is computationally efficient and, thus, scalable to large data sets may augment the abilities of SR-US in imaging microvascular structure and function.

Acoustic source localization with the angular spectrum approach in continuously stratified media

The angular spectrum approach (ASA)-a frequency domain method to calculate the acoustic field-enables highly efficient passive source localization and modeling forward propagation in homogeneous media. If the medium is continuously stratified, a first-order analytical solution may be obtained for the field at arbitrary depth. Simulations show that the proposed stratified ASA solution enables accurate source localization as compared to the uncorrected ASA (error from 1.2 ± 0.3 to 0.49 ± 0.3 wavelengths) at scalings relevant to biomedical, underwater, and atmospheric acoustic applications, and requiring milliseconds on nonspecialized hardware. The results suggest the proposed correction enables efficient and accurate localization in stratified environments.

Heterogeneous Angular Spectrum Method for Trans-Skull Imaging and Focusing

Ultrasound, alone or in concert with circulating microbubble contrast agents, has emerged as a promising modality for therapy and imaging of brain diseases. While this has become possible due to advancements in aberration correction methods, a range of applications, including adaptive focusing and tracking of the microbubble dynamics through the human skull, may benefit from even more computationally efficient methods to account for skull aberrations. Here, we derive a general method for the angular spectrum approach (ASA) in a heterogeneous medium, based on a numerical marching scheme to approximate the full implicit solution. We then demonstrate its functionality with simulations for (human) skull-related aberration correction and trans-skull passive acoustic mapping. Our simulations show that the general solution provides accurate trans-skull focusing as compared to the uncorrected case (error in focal point location of 1.0 ± 0.4 mm vs 2.2 ± 0.7 mm) for clinically relevant frequencies (0.25-1.5MHz), apertures (50-100 mm), and targets, with peak focal pressures approximately 30 ± 17% of the free field case, with the effects of skull attenuation and amplitude shading included. In the case of source localization, our method leads to an average of 75% error reduction (from 2.9 ± 1.8 mm to 0.7 ± 0.5 mm) and 40-60% increase in peak intensity, evaluated over the range of frequencies (0.4-1.2 MHz), apertures (50-100 mm), and point source locations (40 mm by 50 mm grid) as compared to the homogeneous medium ASA. Overall, total computation times for both focusing and point source localization of the order milliseconds (166 ± 37 ms, compared with 44 ± 4 ms for the homogeneous ASA formulation) can be attained with this approach. Collectively our findings indicate that the proposed phase correction method based on the ASA could provide a computationally efficient and accurate method for trans-skull transmit focusing and imaging of point scatterers, potentially opening new possibilities for treatment and diagnosis of brain diseases.

Evaluation and classification of right ventricular wall motion abnormalities in healthy subjects by 3-tesla cardiovascular magnetic resonance imaging

BACKGROUND

Right ventricular (RV) shape and function serves as an indicator in several types of heart disease such as arrhythmogenic right ventricular dysplasia (ARVD). However, there is no in-depth knowledge of RV motion, even in healthy subjects. The aim of our study was to provide a quantitative analysis of normal variations in RV wall motion in healthy subjects by cardiac magnetic resonance imaging (CMRI).

MATERIAL AND METHODS

The study population consisted of 65 consecutive patients referred for the evaluation of cardiac function by 3 Tesla CMR. Balanced steady-state free-precession images were obtained and areas of disordered RV wall motion were evaluated and classified based on a standardised segmental model for the right ventricle.

RESULTS

In 59 patients (90.8 %) wall motion abnormalities (WMA) of the right ventricle were evident. WMA were predominately detected in the apicolateral segments (72 %) compared with mediolateral (24 %, P < 0.001) and inferolateral segments (4 %, P < 0.001). Dyskinesia was the most frequent wall motion disorder (62.4 %), followed by hypokinesia (20.8 %) and bulging (16.8 %). The mean WMA diameter in the transverse plane (6.4 ± 1.9 mm) was significantly shorter compared with the diameter in the horizontal long-axis (8.1 ± 3.6 mm, P = 0.002) and short-axis plane (10.7 ± 4.6 mm).

CONCLUSION

WMA of the right ventricle are common. Therefore, one should be aware that these nonpathological wall motion disorders can easily be mistaken for a pathological regional wall motion contraction, particularly in ARVD where to date, clear wall motion criteria are lacking.

Intra-aortic balloon pump (IABP) counterpulsation improves cerebral perfusion in patients with decreased left ventricular function

Background:

The current goal of treatment after acute ischemic stroke is the increase of cerebral blood flow (CBF) in ischemic brain tissue. Intra-aortic balloon pump (IABP) counterpulsation in the setting of cardiogenic shock is able to reduce left ventricular afterload and increase coronary blood flow. The effects of an IABP on CBF have not been sufficiently examined. We hypothesize that the use of an IABP especially enhances cerebral blood flow in patients with pre-existing heart failure.

Methods:

In this pilot study, 36 subjects were examined to investigate the effect of an IABP on middle cerebral artery (MCA) transcranial Doppler (TCD) flow velocity change and relative CBF augmentation by determining velocity time integral changes (ΔVTI) in a constant caliber of the MCA compared to a baseline measurement without an IABP. Subjects were divided into two groups according to their left ventricular ejection fraction (LVEF): Group 1 LVEF >30% and Group 2 LVEF ≤30%.

Results:

Both groups showed an increase in CBF using an IABP. Patients with a LVEF ≤30% showed a significantly higher increase of ΔVTI in the MCA under IABP augmentation compared to patients with a LVEF >30% (20.9% ± 3.9% Group 2 vs.10.5% ± 2.2% Group 1, p<0,05). The mean arterial pressure (MAP) increased only marginally in both groups under IABP augmentation.

Conclusions:

IABP improves cerebral blood flow, particularly in patients with pre-existing heart failure and highly impaired LVEF. Hence, an IABP might be a treatment option to improve cerebral perfusion in selected patients with cerebral misperfusion and simultaneously existing severe heart failure.

Tricuspid annular plane systolic excursion assessed using MRI for semi-quantification of right ventricular ejection fraction

OBJECTIVE

Accurate determination of right ventricular volume and ejection fraction (RVEF) is established using MRI. Automatic contour detection of the right ventricular endocardial border is not established in clinical practice, resulting in considerable manual efforts to quantify RVEF. Using transthoracic echocardiography (TTE), the tricuspid annular plane systolic excursion (TAPSE) has proved its worth for quantification of RVEF and risk prediction. Therefore, the aim of this study was to clarify whether TAPSE assessed with MRI as a fast and easily obtainable parameter correlated with volumetric quantification of RVEF.

METHODS

Right ventricular volumes and RVEF were measured with the standardised slice-summation method at MRI. MRI-TAPSE was defined as maximum apical excursion of lateral tricuspid annular plane and measured in a four-chamber view using steady-state free precession sequences. Additionally, MRI-TAPSE was compared with TAPSE assessed using TTE.

RESULTS

76 consecutive patients (aged 58±17 years) were examined. At MRI, right end-diastolic volumes were 97±36 ml, right end-systolic volumes were 57±27 ml and the mean RVEF was 42±14%. MRI-TAPSE was determined with 19±6 mm and correlated well at linear regression analysis with volumetric RVEF (r=0.72, p<0.001). Furthermore, MRI-TAPSE discriminated sufficiently between patients with impaired and normal RVEF. Multiplying MRI-TAPSE by 2.5 led to values close to the RVEF by volumetry. Additionally, MRI-TAPSE correlated well with TAPSE determined using TTE. The inter- and intra-observer variabilities of MRI-TAPSE determination were low (3.1% and 1.8%).

CONCLUSION

TAPSE assessed with MRI is a fast and easily obtainable parameter which correlates well with volumetric quantification of RVEF.

Breastfeeding habits in families with Type 1 diabetes

AIMS

Breastfeeding is acknowledged to be beneficial for child development. Women with diabetes may be more likely not to breastfeed their children because of neonatal morbidity and instability in diabetes control. The aim of this study was to assess the effect of maternal Type 1 diabetes on breastfeeding habits.

METHODS

Full breastfeeding and any breastfeeding were reported in the first year of life in 1560 children born in Germany between 1989 and 2004. Of those, 997 children had a mother with Type 1 diabetes, and the remaining 563 children had a father or sibling with Type 1 diabetes.

RESULTS

Fewer children of mothers with Type 1 diabetes were breastfed than children of non-diabetic mothers (77 vs. 86%; P < 0.0001) and, amongst breastfed children, there was a shorter duration of full breastfeeding (12 vs. 17 weeks; P < 0.0001) and any breastfeeding (20 vs. 26 weeks, P < 0.0001) in children of mothers with Type 1 diabetes compared with children of non-diabetic mothers. Other factors associated with reduced frequency and duration of breastfeeding were pre-term delivery (P < 0.0001), young maternal age (P < 0.0001), and firstborn children (P < 0.0001). After stratification for each of these factors, breastfeeding remained significantly less frequent and of less duration in children of mothers with Type 1 diabetes as compared with children of non-diabetic mothers.

CONCLUSIONS

Mothers with Type 1 diabetes breastfeed their children less than international recommendations. Counselling to increase frequency and duration of breastfeeding may be warranted in this population.

Transcatheter closure of patent foramen ovale (PFO) in patients with paradoxical embolism Periprocedural safety and mid-term follow-up results of three different device occluder systems

AIMS

Interventional PFO closure has previously been reported to reduce the risk for recurrent thromboembolic events. The aim of the present study was to evaluate three different occluder systems in respect to (a) the safety and practicability and (b) the mid-term risk of recurrent thromboembolic events.

METHODS AND RESULTS

Since 08/98 until 12/02, 307 consecutive patients (138 women, 169 men, mean age 43 years) with a symptomatic PFO underwent PFO closure using the PFO-Star ( n=177), Amplatzer PFO occluder ( n=69) and CardioSeal/Starflex ( n=61 ). Implantation was successful in all patients. Periinterventional complications occurred in 9 patients (5x ST-segment elevations, 1x arteriovenous fistula, 2x TIA, 1x device dislodgement). All of them were reversible and not associated with a specific type of device. During the median follow-up of 24 months (25/75th percentiles: 14/37 months), the annual risk of recurrence was 0.6% for TIA, 0% for stroke and 0.2% for peripheral embolism (PFO-Star: 0.8%, Amplatzer PFO occluder: 0.7% and CardioSeal/Starflex: 1.0%).

CONCLUSION

Interventional PFO closure appears to be safe and a promising technique in symptomatic PFO patients with a low incidence of periinterventional complications and recurrent thromboembolic events using three different devices (PFO-Star, Amplatzer PFO occluder or the CardioSeal/Starflex).

Nitrergic neurons make synapses on dual-input dendritic spines of neurons in the cerebral cortex and the striatum of the rat: implication for a postsynaptic action of nitric oxide

Pre-embedding electron microscopic immunocytochemistry was used to examine the ultrastructure of neurons containing nitric oxide synthase and to evaluate their synaptic relationships with target neurons in the striatum and sensorimotor cerebral cortex. Intense nitric oxide synthase immunoreactivity was found by light and electron microscopy in a type of aspiny neuron scattered in these two regions. The intensity of the labeling was uniform in the soma, dendrites and axon terminals of these neurons. In both forebrain regions, nitric oxide synthase-immunoreactive neurons received synaptic contacts from unlabeled terminals, which were mostly apposed to small-caliber dendrites. The unlabeled symmetric contacts were generally about four times as abundant as the unlabeled asymmetric contacts on the nitric oxide synthase-immunoreactive neurons. Terminals labeled for nitric oxide synthase were filled with synaptic vesicles and were observed to contact unlabeled neurons. Only 54% (in the cerebral cortex) and 44.3% (in the striatum) of the nitric oxide synthase-immunoreactive terminals making apposition with the target structures were observed to form synaptic membrane specializations within the plane of the randomly sampled sections. The most common targets of nitric oxide synthase-immunoreactive terminals were thin dendritic shafts (54% of the immunoreactive terminals in the cortex and 75.7% of the immunoreactive terminals in the striatum), while dendritic spines were a common secondary target (42% of the immunoreactive terminals in the cortex and 20.6% of the immunoreactive terminals in the striatum). The spines contacted by nitric oxide synthase-immunoreactive terminals typically also received an asymmetric synaptic contact from an unlabeled axon terminal. These findings suggest that: (i) nitric oxide synthase-immunoreactive neurons in the cortex and striatum preponderantly receive inhibitory input; (ii) nitric oxide synthase-containing terminals commonly make synaptic contact with target structures in the cortex and striatum; (iii) spines targeted by nitric oxide synthase-containing terminals in the cortex and striatum commonly receive an asymmetric contact as well, which may provide a basis for a synaptic interaction of nitric oxide with excitatory input to individual spines.

The interaction of bacteriophage P2 B protein with Escherichia coli DnaB helicase

Bacteriophage P2 requires several host proteins for lytic replication, including helicase DnaB but not the helicase loader, DnaC. Some genetic studies have suggested that the loading is done by a phage-encoded protein, P2 B. However, a P2 minichromosome containing only the P2 initiator gene A and a marker gene can be established as a plasmid without requiring the P2 B gene. Here we demonstrate that P2 B associates with DnaB. This was done by using the yeast two-hybrid system in vivo and was confirmed in vitro, where (35)S-labeled P2 B bound specifically to DnaB adsorbed to Q Sepharose beads and monoclonal antibodies directed against the His-tagged P2 B protein were shown to coprecipitate the DnaB protein. Finally, P2 B was shown to stabilize the opening of a reporter origin, a reaction that is facilitated by the inactivation of DnaB. In this respect, P2 B was comparable to lambda P protein, which is known to be capable of binding and inactivating the helicase while acting as a helicase loader. Even though P2 B has little similarity to other known or predicted helicase loaders, we suggest that P2 B is required for efficient loading of DnaB and that this role, although dispensable for P2 plasmid replication, becomes essential for P2 lytic replication.

Comparative messenger ribonucleic acid analysis of immediate early genes and sex steroid receptors in human leiomyoma and healthy myometrium

To shed light on the molecular mechanisms involved in the pathogenesis of uterine leiomyomas, transcript levels of the immediate early genes c-fos, c-myc, and c-jun and of the estrogen receptor (ER) and progesterone receptor (PR) were determined in tissue samples of human myometrium and leiomyoma. The messenger RNA (mRNA) content was analyzed by RT-PCR. mRNAs for c-fos, c-myc, c-jun, ER, and PR were detected in all 18 samples of leiomyoma and corresponding myometrial tissue collected in this study. Interestingly, in contrast to healthy tissues, we found a distinct and significant reduction of c-fos mRNA in the tumor. These data were substantiated by the finding of lowered c-Fos protein levels in leiomyomas tissues. Moreover, transcripts of c-jun and c-myc were less abundant in most of the leiomyomas than in the myometrium. This different expression of the protooncogenes in leiomyomas and myometrium was independent of the phase of the menstrual cycle in which samples were collected. In contrast to the reduced transcript levels observed for the immediate early genes, the ER and PR mRNA contents of the leiomyomas and myometrium did not differ. These results were confirmed by immunohistochemical studies for ER and PR protein. In conclusion, our data show that the deregulated expression of protooncogenes, especially of c-fos, is linked to the pathogenesis of leiomyomas. Confirmation of a potential role of downregulated c-fos levels for the benign character of these tumors requires further investigation. Additionally, the findings suggest that sex steroids do not influence the different expression patterns of c-fos, c-myc, and c-jun in leiomyomas, as compared with myometrium.

A preliminary evaluation of the lunar expert-XL for bone densitometry and vertebral morphometry

We have evaluated the Lunar Expert-XL for standard bone mineral densitometry (BMD) and for morphometric imaging of the spine in the lateral projection. The short-term precision in vitro of the Expert-XL for BMD measurements was 0.7% for the Hologic and European spine phantoms, and the long-term stability (15-month) measurements had a 1.1% coefficient of variation. The precision in vivo for three operators examining a group of 10 premenopausal women was 0.9-1.5% for lumbar spine (L2-L4), 1.7-2.2% for the femoral neck, and 0.9% for the total hip region of interest. For a group of nine postmenopausal women, the lumbar spine, femoral neck, and total femur precision ranges were 2.0-2.4, 1.2-2.9, and 1.6-1.7% respectively. For L2-L4, BMD comparison between the Expert-XL and DPX-L yielded a correlation coefficient of r = 0.98, a slope of 0.86, and an intercept of 0.139 g/cm2. The femoral neck results were r = 0.92, slope = 1.00, and intercept = 0.03 g/cm2. In an evaluation of the Expert-XL for lateral morphometry, we employed a group of 16 postmenopausal women. Comparison of vertebral dimensions between the Expert-XL and radiographic morphometry showed strong agreement (r = 0.97), but the interobserver variability for vertebral height was higher for the Expert-XL than for radiographs (3-5% vs. 1-2%). In a subset of four women who had repeat scans, the interscan precision for measuring vertebral dimensions was 1.9, 4.1, and 43% for the L1-L4, T12-T8, and T7-T5 levels respectively. In the Expert-XL images, it was possible to identify clearly L4-T4 in 10 of 16 patients and L4-T6 in 15 of 16, indicating potential utility for vertebral fracture prescreening.

Antioxidant function of ambroxol in mononuclear and polymorphonuclear cells in vitro

This study quantifies the antioxidant function of ambroxol (2-amino-3,5-dibromo-N-[trans-4-hydroxycyclohexyl]benzylamine) in vitro. Polymorphonuclear cells (PMN) and mononuclear cells were isolated from the blood of healthy volunteers (n = 46) to determine reactive oxygen species (ROS) by luminol-enhanced chemiluminescence. Ambroxol or the controls N-acetylcysteine (NAC), nacystelyn (NAL), glutathione (GSH), superoxide dismutase (SOD), catalase, and the combination of SOD/catalase were incubated for 1 or 2 h with zymosan-activated cells in vitro using concentrations ranging from 10(-6) to 10(-3) mol/liter. Reduction of ROS-mediated luminescence was similar within the cell types. Ambroxol (10(-4) mol/liter) reduced ROS about 75% (1-h incubation) and 98% (2-h incubation), respectively (p < 0.001). SOD and SOD/catalase, but not the H2O2-catalyzing substances (NAC, NAL, GSH, and catalase), reduced cellular ROS. This indicates that inflammatory cells predominantly generate O2-, which can be scavenged by ambroxol. The antioxidant function of ambroxol with increasing incubation time suggests additional cellular antiinflammatory properties of this substance. Our results indicate that good antioxidant function of ambroxol is related mainly to direct scavenger function of reactive oxygen metabolites such as O2-. However, an antioxidative effect of ambroxol may also be associated with the reduction of prooxidative metabolism in inflammatory cells. Concluding from this observation, and because of the well known high affinity of ambroxol for lung tissue, ambroxol may be an alternative in antioxidant augmentation therapy, particularly in pulmonary diseases characterized by an overburden of toxic oxygen metabolites.

Calcitonin receptor mRNA expression in the human prostate

OBJECTIVES

A subpopulation of prostate neuroendocrine (NE) cells contain calcitonin (CT). It has been postulated that CT-producing cells in the prostate account for the high CT level in the semen, and may be involved in the regulation of other epithelial cells via a paracrine mechanism. The presence of CT binding sites in the plasma membrane fraction of prostate tissue has been demonstrated by radioligand binding assay. In the present study, we investigated the CT receptor gene expression in the human prostate, a key component of the autocrine/paracrine loop in the CT functional pathway.

METHODS

Reverse transcription polymerase chain reaction (RT-PCR) was carried out to evaluate the CT receptor mRNA expression in normal prostate tissue. Subsequent DNA sequencing was used to verify RT-PCR amplified products and to determine the isoform of the receptor. To define the location of the CT receptor expression, nonradioactive in situ hybridization was performed with a digoxigenin-labeled probe complementary to the coding region of the CT receptor mRNA. A polyclonal antibody against CT was used to reveal the CT-secreting cells in the prostate.

RESULTS

CT receptor MRNA expression was detected in the prostate tissue. Further analysis of the DNA sequence showed that CT receptor expressed in the prostate was the isoform without a 16-amino acid insert in the first intracellular domain. In situ hybridization revealed that CT receptor was present in the prostate NE cells. Immunocytochemical staining of mirror image sections showed that some CT-secreting cells also expressed CT receptor.

CONCLUSIONS

CT receptor expression in the prostate, a key component in the CT functional pathway, is located in subsets of dispersed NE cells (CT secreting and CT nonsecreting), which indicates that prostate CT may play an important role in the autocrine/paracrine regulation of the prostate NE system.

Nucleotide sequence of the herpes simplex virus type 2 gene encoding the protease and capsid protein ICP35

The complete nucleotide sequence of the gene encoding the protease and ICP35 capsid protein of herpes simplex virus (HSV) type 2 strain G has been determined. The gene consisits of a 1908 bp open reading frame capable of encoding 636 amino acids. Comparative nucleotide sequence analysis of the gene with published HSV-1 sequences revealed that the HSV-2 nucleic acid segment most likely encodes two distinct proteins. The first protein is the HSV-2 protease, which is required for the assembly of the herpes virus capsid. The second protein has been previously designated as ICP35 in HSV-1, and belongs to the family of herpesvirus capsid proteins.

Immunoreactive parathyroid hormone-related protein is present in human seminal plasma and is of prostate origin

Parathyroid hormone-related protein (PTHrP) is a regulatory peptide that has been associated with normal fetal growth and differentiation as well as the regulation of fetal calcium. We recently demonstrated the expression of PTHrP in neuroendocrine cells of human prostatic glands. The present study was undertaken to determine if semen contained PTHrP and to determine if there were any differences in seminal PTHrP between normal and vasectomized men. Radioimmunoassay was used to examine whether immunoreactive PTHrP in seminal fluid is secreted by the prostate. Significant quantities of immunoreactive PTHrP were detected in all seminal samples from normal men of ages 24-34 years (mean +/- SD, 12.94 +/- 8.2 ng/ml). Vasectomy did not decrease the semen levels of PTHrP (25.53 +/- 12.14 ng/ml). In addition, immunohistochemical evaluation with a monoclonal antibody used in our previous study did not show PTHrP immunostaining in the seminal vesicles. These findings indicate that seminal PTHrP is predominantly of prostatic origin. Moreover, the significant correlations between PTHrP and calcium levels in human seminal plasma from both normal (P < 0.001) and vasectomized (P < 0.02) patients suggest that PTHrP may serve as a regulatory factor of calcium secretion in the prostate.

Single-laboratory evaluation of EPA method 8080 for determination of chlorinated pesticides and polychlorinated biphenyls in hazardous wastes

Method 8080, as published in the Second Edition of "Test Methods for Evaluating Solid Waste," EPA Manual SW-846, has been evaluated in a single-laboratory study. The Florisil procedure recommended in Method 8080 for sample cleanup does not separate organochlorine pesticides (OCPs) from the polychlorinated biphenyls (PCBs). Consequently, gas chromatographic analysis of OCPs on the packed column recommended in the method may result in false identifications or in no identifications at all when PCBs are present. Therefore, silica gel was substituted for Florisil, a capillary column was substituted for the packed column, and a sulfur cleanup procedure was incorporated in the method. The revised method was evaluated with samples spiked at 3 concentrations. Precision and accuracy indicate that the revised method can be reliably applied to the determination of OCPs and PCBs in liquid and solid matrixes. Detection limits for liquid matrixes range from 0.02 to 0.09 micrograms/L for OCPs and from 0.5 to 0.9 micrograms/L for PCBs. Detection limits for solid matrixes range from 1 to 6 micrograms/kg for OCPs and from 60 to 70 micrograms/kg for PCBs.

Effect of intravesical administration of tumor necrosis serum and human recombinant tumor necrosis factor on a murine bladder tumor

The effect of intravesical administration of tumor necrosis factor (TNF) on the implantability and growth of bladder cancer was studied using the murine tumor model, MBT-2. Crude TNF was prepared from serum (TNS) of BCG infected rats after injection of endotoxin or the recombinant product of human TNF-alpha was used. Treatment was begun 24 hr. or seven days after tumor instillation and repeated three times. Tumor implantability and tumor weight were determined on day 21. Low dose TNF (200 U), given in the form of TNS, failed to suppress the growth of established tumors (seven-day tumor). It did, however, significantly reduce tumor implantability. The growth of seven-day tumors was significantly suppressed by administration of higher dose of TNF (3,700 U) given in recombinant form.

Future of physician recruiting

Group practices need to be wary of assuming that the anticipated surplus of physicians will make recruiting any easier. Problems previously associated with candidate identification will give way to how to best manage the screening, interviewing and evaluation of prospective candidates. Furthermore, increasing numbers of physicians competing for patients in the medical care marketplace will pose a direct threat to established groups. This is already occurring in many areas of the country. A recent example of this is occurring with an 85-person multispecialty group in a city of 120,000 with a service of 220,000. A nearby town of 50,000 with a 200-bed hospital is actively recruiting its own physicians. The result will be a steadily eroding referral base for the large multispecialty group over the next five years.

Anticipation of renal transplant failure by postanastomosis biopsy and immunofluorescence

Ninety-six pre- and postanastomosis allograft biopsies from 48 transplant recipients were studied employing the direct fluorescent antibody procedure. Of the 48 transplants studied, 26 postanastomosis biopsies showed significant blood vessel wall deposits consisting predominantly of 2-4+ staining IgM and C3 deposits. The corresponding preanastomosis biopsies showed only patchy intimal surface staining. All but two of the grafts with positive biopsies had been preserved by the pulsatile perfusion method for various periods of time. Twenty-three of the twenty-six grafts with positive findings failed within 1 month while only 2 of the 19 negative postanastomosis biopsies failed within the 1-month period. Based on these findings actual graft failure occurred in 89% of the patients with postanastomosis transplant biopsies with positive findings. Although crossmatch studies were negative in all cases, further immunologic studies of eluates obtained from positive postanastomosis biopsies revealed the presence of lymphocytotoxic IgM antibodies in three of five cases studied. These findings suggest that rapid deposition of undetected preformed lymphocytotoxic antibodies accumulate in the vessel walls following anastomosis and contribute to transplant failure.