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Biomedical subjects

S J Rosenthal

Publications and source records attributed to S J Rosenthal.

At least 19 recordsLinked to original sources
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↗
PubMed1990

Chest radiography: comparison of high-resolution digital displays with conventional and digital film.

This study was performed to compare the performances of observers using three display formats for chest radiography. The display formats were conventional radiographs, digitized radiographs (2,048 X 2,048 X 12 bits) printed on laser film, and digitized radiographs (2,048 X 2,048 X 12 bits) displayed on a high-resolution (2,560 X 2,048 X 12-bit) gray-scale display. The test set for the study consisted of 163 cases. Sixty-four of the cases were normal, whereas the 99 remaining cases demonstrated one or more common radiographic abnormalities. Nine abnormalities were selected for analysis: costophrenic angle blunting, interstitial disease, atelectasis, pneumothorax, parenchymal mass, consolidation, obstructive disease, hilar/mediastinal mass, and apical scarring. Six experienced general radiologists participated in the evaluation. Receiver operating characteristic curves were generated for each abnormality and display format. The results indicate that, while the three display formats are equivalent for the detection of some abnormalities, detectable differences in observer performance may be seen even at 2,048 X 2,048 X 12 bits for the detection of obstructive disease, pneumothorax, interstitial disease, and parenchymal masses.

Humans↗
PubMed1990

Teleradiology: an assessment.

A teleradiology system acquires radiographic images at one location and transmits them to one or more remote sites, where they are displayed and/or converted to hard copy. These systems often employ wide area networks. Their goal is to provide improved radiologic services at all sites on the network. Experience in the use of teleradiology systems has demonstrated the need for a laser film digitizer, an optical disk, and a high-quality display and/or laser film printer at each site. Single-site hardware purchase costs average $196,000, plus an additional 20% for yearly network services. Hardware purchased for a consultation or central referral facility approximates $344,000.

Computer Communication Networks↗
PubMed1989

Quantitative ultrasonography.

A perspective on quantitative techniques in diagnostic ultrasound is presented. The method involves the use of multiple tissue characterization features, pattern recognition methods, and imaging techniques to extract diagnostic information beyond that available with conventional imaging techniques. The information that each acoustic property and characterization feature reveals about physical properties of the tissues is discussed, and examples of clinical and laboratory data are summarized. The emphasis is on features that describe the composition, microscopic structure, and flow characteristics of normal and diseased soft tissues.

Discriminant Analysis↗
PubMed1980

Comparison of computed tomography and ultrasound in abdominal staging of renal cancer.

The relative accuracy of computed tomography (CT) and ultrasound in abdominal staging of renal cancer was determined in 22 patients. CT is capable of detecting tumor invasion of perinephric fat and adjacent muscles, which cannot usually be shown by ultrasound. While both CT and ultrasound demonstrate venous and retroperitoneal tumor extension, CT is more reliable since bowel gas not infrequently obscures the retroperitoneum on ultrasonic scanning. However, ultrasound will often provide valuable information; and whenever a solid renal mass is detected by echography using prone scans, abdominal scans should be obtained for staging pruposes.

Adenocarcinoma↗
PubMed1979

Fetal pseudoascites.

A sonolucent band (pseudoascites) was retrospectively identified beneath the fetal abdominal wall in 39.7% of 141 normal obstetrical sonograms. In 12.6% of the examinations, the band was wide enough to be potentially confused with actual ascites. Pseudoascites was unrelated to fetal age or position, placental location, or equipment used. It was not reliably present on sequential examinations. The origin of this artifact remains unclear.

Ascites↗
PubMed1979

Gray scale ultrasonic appearances of renal transplant rejection.

Ultrasonic examination of renal transplants with special attention to the parenchymal echo pattern has been undertaken in 43 patients. In the normal renal transplant, the pyramids, cortex and renal sinus can be distinguished. Renal transplant rejection is manifested by swelling and decreased echogenicity of the pyramids and hyperechogenic cortex. In addition, large anechoic areas due to hemorrhagic infarcts and necrosis are seen. In long-standing rejection, a normal or small-sized kidney with an irregular intrarenal echo pattern is observed. In 13 cases of acute tubular necrosis, none of the above appearances could be demonstrated. Serial ultrasonic scans are essential to reveal evolutionary changes of the rejection process.

Adolescent↗
PubMed1979

Measurement of oxygen consumption in voltage-clamped epithelia.

Standard apparatus for in vitro study of anuran epithelia was adapted for the incorporation of Clark oxygen electrodes, permitting the concurrent measurement of electrical current (active sodium transport) and oxygen consumption under voltage-clamp conditions, with independent manipulation of the two bathing solutions. Stability was enhanced by electrical isolation of the O2 electrodes, sensitive temperature control (+/- 0.03 degrees C), and constancy of stirring rate. Mean rate of drift was less than 3.7% of the average rate of basal (i.e., nontransport related) O2 consumption. In the present configuration the response time was less than 15 s. Visual fitting of slopes of O2 tension evaluated rates of O2 consumption with adequate accuracy in the physiological range (basal rates averaged about 20 pmol-s-1-cm-2 toad bladder, corresponding to about 10 pmol-s-1-mg-1 dry wt, or about 5 pmol-s-1-ml-1 chamber volume). Rpresentative slopes were read with a standard deviation of 3.5%.

Animals↗
PubMed1979

Use of mass spectrometer to measure CO2 and O2 fluxes in voltage-clamped epithelia.

A quadrupole mass spectrometer was coupled to an Ussing chamber in order to evaluate rates of oxidative metabolism in voltage-clamped epithelia. Well-defined mixing characteristics of the continuously perfused chamber allowed CO2 and O2 concentrations to be related to rates of CO2 efflux, JCO2, and oxygen influx, JO2. The use of a model tissue to simulate step changes in JCO2 validated the treatment, with response within a minute. Monitoring of metabolism was facilitated by use of a desk-top computer, which evaluated JCO2 at 6-s intervals. Concurrent measurements of electrical current and JCO2 were made in the toad urinary bladder in order to relate active sodium transport to metabolism; the use of amiloride to eliminate active transport and the associated metabolism then allowed evaluation of the rates of active Na transport (JNa) and suprabasal metabolism (JsbCO2), and their ratio JNa/JsbCO2. We report the ability to resolve a 5 pmol/s change in CO2 efflux or an 11 pmol/s change in O2 influx rates.

Animals↗