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S J Rosenthal

Publications and source records attributed to S J Rosenthal.

At least 19 recordsLinked to original sources
PubMed2004

Novel fluorescence-based approaches for the study of biogenic amine transporter localization, activity, and regulation.

Pre-synaptic norepinephrine (NE) and dopamine (DA) transporters (NET and DAT) terminate catecholamine synaptic transmission through reuptake of released neurotransmitter. Recent studies reveal that NET and DAT are tightly regulated by receptor and second messenger-linked signaling pathways. Common approaches for studying these transporters involve use of radiolabeled substrates or antagonists, methods possessing limited spatial resolution and that bear limited opportunities for repeated monitoring of living preparations. To circumvent these issues, we have explored two novel assay platforms that permit temporally resolved quantitation of transport activity and transporter protein localization. To monitor the binding and transport function of NET and DAT in real-time, we have investigated the uptake of the fluorescent organic compound 4-(4-diethylaminostyryl)-N-methylpyridinium iodide (ASP+). We have extended our previous single cell level application of this substrate to monitor transport activity via high-throughput assay platforms. Compared to radiotracer uptake methods, acquisition of ASP+ fluorescence is non-isotopic and allows for continuous, repeated transport measurements on both transfected and native preparations. Secondly, we have extended our application of small-molecule-conjugated fluorescent CdSe/ZnS nanocrystals, or quantum dots (Qdots), to utilize antibody and peptide ligands that can identify surface expressed transporters, receptors and other membrane proteins in living cell systems. Unlike typical organic fluorophores, Qdots are highly resistant to bleaching and can be conjugated to multiple ligands. They can also be illuminated by conventional light sources, yet produce narrow, gaussian emission spectra compatible with multiple target visualization (multiplexing). Together, these approaches offer novel opportunities to investigate changes in transporter function and distribution in real-time with superior spatial and temporal resolution.

Antibodies↗
PubMed2001

Ultrasonography for the evaluation of forearm interosseous membrane disruption in a cadaver model.

Recognition of interosseous membrane disruption associated with radial head injury and Essex-Lopresti injury is important, especially if radial head excision is contemplated. Because a widely accepted method to diagnose interosseous membrane disruption does not exist, we evaluated the accuracy of ultrasonography to diagnose this injury in a cadaver model. Nine pairs of cadaver forearms were randomized into 2 groups. The central third of the interosseous membrane of forearms of group 1 was cut, whereas it was visualized but not cut in group 2. A dynamic ultrasound examination was performed to determine interosseous membrane integrity, and static images were made. The static images were evaluated by 2 other radiologists and interpretations were recorded. One radiologist incorrectly interpreted 1 pair of forearms; the other 2 radiologists were 100% accurate. The accuracy of ultrasonography in detecting interosseous injuries was 96% with our methods.

Biomechanical Phenomena↗
PubMed2001

Phase inversion tissue harmonic sonographic imaging: a clinical utility study.

OBJECTIVE: We evaluated the utility of phase inversion tissue harmonic sonographic imaging in a variety of clinical applications. SUBJECTS AND METHODS: Two hundred randomly selected patients were scanned with both fundamental and tissue harmonic methods on a sonography system. The following transducers were used: 2.5 MHz, 20 mm phased array; 3 MHz, 40 mm curved array; 6.5 MHz, 13 mm curved array transvaginal; and 7.5 MHz, 40 mm linear. Operators evaluated visualization of normal and pathologic tissues by tissue harmonic versus fundamental imaging using scores ranging from 1 for much worse visualization to 5 for much better visualization. They also assessed the overall utility of tissue harmonic imaging in the diagnosis of the patient's condition. The studies were saved on magnetooptical disc and were independently reviewed by one of the authors. RESULTS: Tissue harmonic imaging was helpful for all types of examination. Tissue harmonic imaging improved visualization of normal tissue in 49% of the cases and pathologic tissue in 73% of the cases. Tissue harmonic imaging was found to be diagnostically helpful in 43% of the cases and essential to the diagnosis in 6% of the cases. CONCLUSION: Tissue harmonic imaging significantly improves visualization of both normal and pathologic tissues and its selective use has major diagnostic utility in a wide variety of clinical applications.

Female↗
PubMed2000

The measurement of proton stopping power using proton-cone-beam computed tomography.

A cone-beam computed tomography (CT) system utilizing a proton beam has been developed and tested. The cone beam is produced by scattering a 160 MeV proton beam with a modifier that results in a signal in the detector system, which decreases monotonically with depth in the medium. The detector system consists of a Gd2O2S:Tb intensifying screen viewed by a cooled CCD camera. The Feldkamp-Davis-Kress cone-beam reconstruction algorithm is applied to the projection data to obtain the CT voxel data representing proton stopping power. The system described is capable of reconstructing data over a 16 x 16 x 16 cm3 volume into 512 x 512 x 512 voxels. A spatial and contrast resolution phantom was scanned to determine the performance of the system. Spatial resolution is significantly degraded by multiple Coulomb scattering effects. Comparison of the reconstructed proton CT values with x-ray CT derived proton stopping powers shows that there may be some advantage to obtaining stopping powers directly with proton CT. The system described suggests a possible practical method of obtaining this measurement in vivo.

Calibration↗
PubMed1998

Vena caval occlusion after bird's nest filter placement.

BACKGROUND: Inferior vena caval thrombosis as a result of intracaval barrier devices occurs in 6.5% of patients with Greenfield filters. The incidence is less well defined in patients in whom bird's nest filters have been placed. We reviewed our experience with bird's nest filters to determine the incidence of filter-induced caval thrombosis. METHODS: The records of 140 patients with bird's nest filters were reviewed, living patients were interviewed, and the inferior vena cava examined in 37 patients by duplex scanning. RESULTS: Ninety-three patients were available for evaluation. Five of these patients were found to have caval thrombosis by duplex scanning and 2 had clinical symptoms and signs compatible with caval thrombosis. The majority of these patients were on anticoagulants at the time of filter thrombosis. CONCLUSION: The incidence of filter-induced vena caval thrombosis in patients with bird's nest filters (7%) is comparable with that of Greenfield filters. Because of the catastrophic manifestations of this complication and the increasing application of vena caval filters, the role of these filters in the treatment of thrombotic disease needs further critical evaluation.

Adolescent↗
PubMed1995

A precision cranial immobilization system for conformal stereotactic fractionated radiation therapy.

PURPOSE: Conformal radiotherapy has been shown to benefit from precision alignment of patient target to therapy beam (1, 6, 13). This work describes an optimized immobilization system for the fractionated treatment of intracranial targets. A study of patient motion demonstrates the high degree of immobilization which is available. METHODS AND MATERIALS: A system using dental fixation and a thermoplastic mask that relocates on a rigid frame is described. The design permits scanning studies using computed tomography (CT) and magnetic resonance imaging (MR), conventional photon radiotherapy, and high precision stereotactic proton radiotherapy to be performed with minimal repositioning variation. Studies of both intratreatment motion and daily setup reliability are performed on patients under treatment for paranasal sinus carcinoma. Multiple radiographs taken during single treatments provide the basis for a three-dimensional (3D) motion analysis. Additionally, studies of orthogonal radiographs used to setup for proton treatments and verification port films from photon treatments are used to establish day to day patient position variation in routine use. RESULTS: Net 3D patient motion during any treatment is measured to be 0.9 +/- 0.4 mm [mean +/- standard deviation (SD)] and rotation about any body axis is 0.14 +/- 0.67 degrees (mean +/- SD). Day-to-day setup accuracy to laser marks is limited to 2.3 mm (mean) systematic error and 1.6 mm (mean) random error. CONCLUSION: We conclude that the most stringent immobilization requirements of 3D conformal radiotherapy adjacent to critical normal structures can be met with a high precision system such as the one described here. Without the use of pretreatment verification, additional developments in machine and couch design are needed to assure that patient repositioning accuracy is comparable to the best level of patient immobility achievable.

Brain Neoplasms↗
PubMed1995

Comparison of proton and x-ray conformal dose distributions for radiosurgery applications.

Highly focused dose distributions for radiosurgery applications are successfully achieved using either multiple static high-energy particle beams or multiple-arc circular x-ray beams from a linac. It has been suggested that conformal x-ray techniques using dynamically shaped beams with a moving radiation source would offer advantages compared to the use of only circular beams. It is also thought that, generally, charged particle beams such as protons offer dose deposition advantages compared to x-ray beams. A comparison of dose distributions was made between a small number of discrete proton beams, multiple-arc circular x-ray beams, and conformal x-ray techniques. Treatment planning of a selection of radiosurgery cases was done for these three techniques. Target volumes ranged from 1.0-25.0 cm3. Dose distributions and dose volume histograms of the target and surrounding normal brain were calculated. The advantages and limitations of each technique were primarily dependent upon the shape and size of the target volume. In general, proton dose distributions were superior to x-ray distributions; both shaped proton and shaped x-ray beams delivered dose distributions which were more conformal than x-ray techniques using circular beams; and the differences between all proton and x-ray distributions were negligible for the smallest target volumes, and greatest for the larger target volumes.

Biophysical Phenomena↗
PubMed1995

Doppler US of helical flow in the portal vein.

In helical portal venous blood flow, the usual laminar flow in the portal vein is replaced by a spiral. This changes the color Doppler ultrasound (US) appearance to one of alternating or parallel red and blue bands. Duplex US may appear to show hepatopetal, hepatofugal, or simultaneous bidirectional flow depending on placement of the cursor within the helix. Helical portal venous flow is unusual in normal individuals (2.2% of 135 patients). Its presence should prompt further scrutiny for signs of liver disease, particularly portosystemic shunts, as in 20% of 41 patients who subsequently underwent liver transplantation. It is a normal finding immediately after liver transplantation (43% of 35 patients) and transjugular intrahepatic portosystemic shunt (TIPS) creation (28% of 36 patients). In both liver transplant and TIPS recipients, helical flow is usually transient. Its persistence long after transplantation in association with a prolonged increase in portal venous velocity is a useful sign of portal vein stenosis. Helical flow may also occur in cases of neoplastic invasion or displacement of the portal vein.

Blood Flow Velocity↗
PubMed1992

Femtosecond spontaneous-emission studies of reaction centers from photosynthetic bacteria.

Spontaneous emission from reaction centers of photosynthetic bacteria has been recorded with a time resolution of 50 fs. Excitation was made directly into both the special-pair band (850 nm) and the Qx band of bacteriochlorophylls (608 nm). Rhodobacter sphaeroides R26, Rhodobacter capsulatus wild type, and four mutants of Rb. capsulatus were studied. In all cases the fluorescence decay was not single exponential and was well fit as a sum of two exponential decay components. The short components are in excellent agreement with the single component detected by measurements of stimulated emission. The origin of the nonexponential decay is discussed in terms of heterogeneity, the kinetic scheme, and the possibility of slow vibrational relaxation.

Energy Transfer↗
PubMed1992

Computers in ultrasonic imaging.

This article describes the role of computers and digital electronics in state-of-the-art diagnostic ultrasound scanners. An overview of the computational requirements is provided, and limits on color flow image frame rates are discussed. The new scanner architectures emerging may be used to extend current limitations of ultrasonography, making features such as automatic phase aberration correction, speckle reduction, and tissue characterization available.

Humans↗
PubMed1991

Wide area networks for teleradiology.

Teleradiology networks transmit digital radiographic images from one location to another. These networks are wide area networks. Teleradiology networks are used for diagnostic purposes and preview tasks. Wide area networks for teleradiology use public service switching. The use of fiber optics networks provide reduced costs and increased flexibility. An example is presented that compares the cost of teleradiology networks.

Computer Communication Networks↗
PubMed1991

Prenatal and postnatal consequences in the brain and behavior of rats exposed to ultrasound in utero.

As a result of a prior experiment demonstrating damage to the developing cortex of the fetal rat 24 hours after maternal exposure to ultrasound, postnatal consequences of similar exposure on rat behavior were examined. No decrease in postnatal weight or growth rate was found and no significant decrease in cortical thickness was present postnatally at 28 days. In two of four behavioral tests, rats exposed to ultrasound in utero resembled similarly treated controls. In one test, ultrasound-exposed rats showed slower performance, and in one, faster performance. These data provide no consistent evidence that ultrasound exposure resulted in deleterious postnatal effects.

Animals↗
PubMed1990

Acute response of fetal rat telencephalon to ultrasound exposure in utero.

Pregnant rats were exposed to ultrasound or microwaves from transducers located over one uterine horn. Ultrasound intensity (SPTA) was 0.78 W/cm2 for 30 min at a frequency of 2.5 MHz. Microwave exposure was used to reproduce approximately the rate of rise of uterine temperature of the rats exposed to ultrasound. The average peak temperature was 40.1 degrees C for ultrasound exposure and 42.2 degrees C for microwave exposure. On Gestational Day 16, 24 h after exposure, fetuses were removed and prepared for morphological examination of the developing cerebral cortical mantle. Morphometric measurements were made of nuclear area of subventricular zone cells, number of mitoses per mm in the ventricular zone, number of pyknotic cells in the mantle per mm, and number of ventricular macrophages per mm. Both exposures increased nuclear size and numbers of pyknotic cells and macrophages, and decreased the number of mitotic figures. The data from the four measurements were evidence of damage from ultrasound similar to the effects produced by microwave heating. The thermal effects of ultrasound, even at relatively low levels of rise in temperature, may have been the cause of the damage to the fetal cortex in these experiments or may have interacted with other effects of ultrasound energies to produce damage to developing neurons.

Animals↗
PubMed1990

Pitfalls and differential diagnosis in biliary sonography.

Ultrasonography has a primary role in the imaging of biliary disease. Most cases are straightforward, but the authors emphasize unusual manifestations, uncommon diseases, and artifacts that may present diagnostic challenges. Issues in differential diagnosis are discussed for the following findings: internal gallbladder echoes (calculi vs tumefactive sludge, air, hematobilia, parasitic infestation, cholecystosis, neoplasia, and artifacts), gallbladder wall thickening (acute cholecystitis vs acalculous cholecystitis, artifacts, ascites, hypoalbuminemia, hepatitis, and sclerosing cholangitis), pericholecystic fluid (cholecystitis vs ascites, perforated ulcer, and trauma), bile duct dilatation (biliary obstruction vs sclerosing cholangitis, biliary air, anomalous portal system, biliary atresia, Caroli disease, and cholangiocarcinoma), perinatal and neonatal biliary disease, and sclerosing cholangitis.

Biliary Tract Diseases↗