Premature ventricular contractions during triggered imaging with ultrasound contrast.

BACKGROUND: Premature ventricular contractions (PVCs) were observed during triggered second harmonic imaging of a contrast agent for myocardial perfusion assessment, with continuous infusion of the contrast agent. Further investigation into the relation of this phenomenon to both ultrasound energy and the contrast agent was carried out during a subsequent bolus-versus-infusion study. METHODS AND RESULTS: Two open-label studies in healthy male volunteers were performed. The initial study was a dose-response study in 10 subjects, which compared 3 infusion rates. Each volunteer received 3 continuous infusions with different infusion rates of the contrast agent for either 10 (n = 6) or 20 (n = 4) minutes. End-systolic triggered imaging with a mechanical index (MI) of 1.5 was used throughout this part of the study. The second study compared bolus injection with a continuous infusion in 9 volunteers, with a single-dose level but different imaging modalities: end-systolic and end-diastolic triggered imaging at MIs of both 1.1 and 1.5. Spontaneous baseline PVCs were uncommon: 10 in 344 minutes (0.03 PVC/min, maximal 1 PVC/min) of baseline imaging. During end-diastolic triggering, no increase in PVCs was seen, irrespective of MI. A significant increase to 1.06 PVC/min (P <.001) was seen during end-systolic imaging with an MI of 1.5, but not with an MI of 1.1. The increase in PVC rate was dose-dependent in the initial study. CONCLUSION: Imaging of contrast agents with high acoustic pressures can cause PVCs if end-systolic triggering is used. This effect is related to both the dose of contrast agent and acoustic pressure. It does not occur during end-diastolic triggered imaging. Precautionary measures would include using lower MIs or end-diastolic triggering.

Harmonic imaging of porcine intraovarian arteries using sonographic contrast medium: initial findings.

The purpose of this study was to visualize, using harmonic gray-scale imaging, blood flow in porcine intraovarian arteries after intravenous injections of a bubble-based sonographic contrast medium. Five female pigs underwent laparotomy. Surgically isolated ovaries were scanned intraperitoneally by an ultrasound system reconfigured with software changes to accomplish harmonic imaging. The transmission and receiving frequencies were set at 3.75 and 7.5 MHz, respectively. After injection of the sonographic contrast medium (Aerosomes) into a peripheral vein, the ovaries were imaged in the harmonic mode. Ten minutes later, another contrast injection was administered and conventional gray-scale imaging of the ovary performed. In all five pigs, intraovarian arteries were clearly identified upon harmonic imaging as brightly echogenic moving columns. The arterial blood pool appeared brighter during systole than diastole. Upon ultrasound contrast-assisted conventional gray-scale imaging, intraovarian arteries were not visualized in four pigs and poorly visualized in one. We conclude that contrast-assisted harmonic imaging can adequately visualize blood flow in intraovarian arteries of surgically exposed porcine ovaries. Clinically, harmonic imaging may facilitate early detection of tumor-induced angiogenesis in the human ovary.

The isolation of U1 RNA-binding antibody fragments from autoimmune human-derived bacteriophage display libraries.

Almost seventy percent of systemic lupus erythematosus (SLE) patients produce autoantibodies specific for U1 RNA, the RNA component of the U1snRNP complex involved in pre-mRNA splicing. Human anti-U1 RNA antibodies from SLE patients provide an ideal model for studying protein-RNA interactions. In addition, a more in depth look at the mechanism by which an antibody interacts with U1 RNA will lend insight into immune disregulation and may have therapeutic potential in the treatment of autoimmune disease. The possibility of cloning an anti-U1 RNA antibody has been investigated using "phage Fab display," a method involving the display of Fab fragments on the outer surface of filamentous phage. Human Fab cDNA libraries were constructed using total RNA collected from leukophoresed anti-U1 RNA antibody-positive SLE patient sera. The resulting Fab genes were subcloned into a phagemid expression vector which produced phage displaying Fab fragments in E.coli1. Libraries were enriched for U1 RNA-binding clones after several rounds of affinity selection against purified, in vitro transcribed U1 RNA. Putative U1 RNA-binding clones were identified by colony lift and the corresponding Fab genes were expressed and purified from E.coli for binding studies. Results demonstrate that RNA-binding Fab can be isolated from combinatorial phage display libraries.

Solitary retinal astrocytoma.

Astrocytic hamartomas are typically white, well-circumscribed, elevated lesions arising in single or multiple areas of the retina and epi- or peripapillary optic nerve. These lesions are most commonly associated with tuberous sclerosis and less commonly associated with neurofibromatosis. However, solitary retinal or optic nerve astrocytomas can be found in normal individuals. This paper reviews the case of a 48-year-old white female who presented with a solitary retinal astrocytoma of the right eye, without any other physical or ocular disorder. The histopathological and clinical appearance and course of astrocytomas, its differential diagnosis from other retinal and optic nerve lesions, and its association with tuberous sclerosis are discussed.

Evaluating Doppler devices using a moving string test target.

Two moving string test targets have been developed and used to characterize ultrasound Doppler instrumentation. The characteristics investigated were sample volume size and location in space, amplitude sensitivity to Doppler shift, and resolution of Doppler direction. The tests were performed on a combined echo/Doppler instrument and on an annular array system. The procedures can be carried out routinely in the clinical laboratory to ensure that the instrument is working properly or as an aid for correct interpretation of acquired data.

Reliability and validity of the Group Embedded Figures Test for a grade school sample.

Data on validity of the Group Embedded Figures Test for 22 sixth grade students (9 boys and 13 girls) were obtained. 50 wk. later all subjects were individually screened on the Portable Rod-and-Frame Test and after a period of 2 more weeks, when they were retested on the embedded figures, data on reliability were obtained. Long-term coefficients of stability of .80 and .71 for the 9 boys and 13 girls, respectively, were obtained. Coefficients of internal consistency ranged from .83 to .98 for boys and girls. Coefficients reflecting both construct and concurrent validity were -.60 and .00 for boys and girls, respectively. Customary sex differences with respect to field-dependence--independence were not observed for these small samples.

Field dependence--independence and performance with the passive transformation.

An investigation of the influence of children's levels of field dependence-independence on their performance with the passive transformation is presented. Eighty 6th graders classified as field dependent or field independent were presented with sentence-question combinations, each in either the active or passive voice, and numbers of correct responses were recorded. Results showed that field-independent subjects performed better over-all than did field-dependent subjects. The three-way interaction of field dependence-independence, sentence voice, and question voice was also significant. Field-dependent subjects performed significantly more poorly on the active-passive and passive-active combinations than on the active-active and passive-passive combinations. There were no significant differences among the four treatments within the field-independent subjects. Thus field-dependent subjects had greatest difficulty with combinations requiring them to isolate the essential elements of a sentence and use them in a different form; field-independent subjects did not experience this difficulty.