Search PubMed⌕ Search

Biomedical subjects

R Siegel

Publications and source records attributed to R Siegel.

14 recordsLinked to original sources
PubMed1992

Alterations of phasic coronary artery flow velocity in humans during percutaneous coronary angioplasty.

BACKGROUND AND OBJECTIVES: Studies using Doppler catheters to assess blood flow velocity and vasodilator reserve in proximal coronary arteries have failed to demonstrate significant improvement immediately after coronary angioplasty. Measurement of blood flow velocity, flow reserve and phasic diastolic/systolic velocity ratio performed distal to a coronary stenosis may provide important information concerning the physiologic significance of coronary artery stenosis. This study was designed to measure these blood flow velocity variables both proximal and distal to a significant coronary artery stenosis in patients undergoing coronary angioplasty. METHODS: A low profile (0.018-in.) (0.046-cm) Doppler angioplasty guide wire capable of providing spectral flow velocity data was used to measure blood flow velocity, flow reserve and diastolic/systolic velocity ratio both proximal and distal to left anterior descending or left circumflex coronary artery stenosis. These measurements were made in 38 patients undergoing coronary angioplasty and in 12 patients without significant coronary artery disease. RESULTS: Significant improvement in mean time average peak velocity was noted in distal coronary arteries after angioplasty (before 19 +/- 12 cm/s; after 35 +/- 16 cm/s; p less than 0.01). Increases in proximal average peak velocity after angioplasty were less remarkable (before 34 +/- 18 cm/s; after 41 +/- 14 cm/s; p = 0.04). Mean flow reserve remained unchanged after angioplasty both proximal (1.5 +/- 0.5 vs. 1.6 +/- 1; p greater than 0.10) and distal (1.6 +/- 1 vs. 1.5 +/- 0.8; p greater than 0.10) to a coronary stenosis. Before angioplasty, mean diastolic/systolic velocity ratio measured distal to a significant stenosis was decreased compared with that in normal vessels (1.3 +/- 0.5 vs. 1.8 +/- 0.5; p less than 0.01). After angioplasty, distal abnormal phasic velocity patterns generally returned to normal, with a significant increase in mean diastolic/systolic velocity ratio (1.3 +/- 0.5 vs. 1.9 +/- 0.6; p less than 0.01). Phasic velocity patterns and mean diastolic/systolic velocity ratio measured proximal to a coronary stenosis were not statistically different from values in normal vessels (1.8 +/- 0.8 vs. 1.8 +/- 0.5; p greater than 0.10) and did not change significantly after angioplasty (1.8 +/- 0.8 vs. 2.13 +/- 0.9; p greater than 0.10). CONCLUSIONS: Flow velocity measurements may be performed distal to a coronary stenosis with the Doppler guide wire. Phasic velocity measurements made proximal to a coronary stenosis differed from those in the distal coronary artery. Both proximal and distal flow reserve measurements made immediately after angioplasty were of limited utility. Changes in distal flow velocity patterns and diastolic/systolic velocity ratio appeared to be more relevant than the hyperemic response in assessing the immediate physiologic outcome of coronary angioplasty.

Angioplasty, Balloon, Coronary↗
PubMed1992

Disseminated herpes simplex infection in a twin: the role of the "stat" autopsy in immediate therapeutic intervention for survival of multiple birth neonates.

Multiple birth neonates are unique in sharing similar intrauterine, and commonly the extrauterine, environments. The development of an infectious disease in one infant during the perinatal period assumes special significance in this setting, and the other siblings are often at high risk for a similar disease. Under these circumstances it is important to make a rapid etiologic diagnosis to provide appropriate therapeutic intervention. The immediate, or "stat", autopsy is a diagnostic modality involving the use of multiple procedures for the rapid diagnosis of perinatal infection which may be lifesaving in the setting of multiple birth neonates. This report describes the use of the "stat" autopsy to diagnose a fatal case of disseminated herpes simplex infection in a twin, which lead to the immediate treatment of the surviving sibling with appropriate antiviral medication.

Acyclovir↗
PubMed1992

Stable expression of cloned human antibody genes in murine myeloma cells.

Human monoclonal antibodies (MAbs) offer potential advantages over murine MAbs for therapy because they are not likely to elicit immune responses and are expected to interact more efficiently with the human immune system to activate therapeutically useful functions. Traditional methods for obtaining human MAbs (i.e., immortalization of B cells by cell fusion or transformation) can result in low and unstable antibody secretion. Recently, methods have been devised for direct cloning of human variable region genes via polymerase chain reaction and phage combinatorial libraries. Both types of human MAb production can benefit from expression systems that support the stable, high-level antibody secretion required for therapeutic use. Using an existing human-derived hybridoma that secretes a human IgM antibody as a convenient source of antibody genes, we have demonstrated that cloned human antibody genes can be efficiently expressed in murine myeloma cells and that cell lines with properties suitable for large-scale economical production can be obtained. We were unable to detect any differences between the antibodies produced by the original hybridoma and the engineered cell line. In addition, we were able to express an IgG form of the antibody, showing that expression of a recombinant human antibody need not be limited to the original antibody class.

Animals↗
PubMed1978

Musical murmurs: an echo-phonocardiographic study.

Five patients with muscial murmurs were studied noninvasively with simultaneous echocardiography and phonocardiograpy and phonocardiography. Three patients had aortic regurgitation, one mitral regurgitation and one tricuspid regurgitation. The frequency of the muscial murmurs ranged from 40 to 158 cycles/sec. The patient with tricuspid regurgitation manifested an inspiratory honk. Simultaneous echo-phonocardiography revealed regular valve leaflet flutter (aortic, mitral or tricuspid) at a frequency identical to that of the simultaneously recorded muscial murmur. This study demonstrates that echocardiography is a useful noninvasive tool in identifying the site of origin of musical murmurs.

Adult↗
PubMed1978

Ultrastructure and mechanical activity expressed by striated muscle in culture.

Newly devised assay procedures for quantitating the mechanical capabilities of striated muscle fibers grown in cell culture have permitted the correlation of cytological features with the ability to respond mechanically to electrical and chemical stimuli during development. By developmental timing and by physiological characteristics, three distinct mechanical activities can be distinguished: : TWITCH, contracture and wave propagation (escalation). Parallel electron microscopy studies suggest that contracture and escalation require significantly greater internal membrane development than twitch. The assay procedures have revealed that fibers developed in culture from genetically dystrophic chick muscle cells display a heightened electrical threshold for a twich response, but are otherwise similar to normal fibers. Cultured chick fibers, whether of leg or breast origin, exhibit similar ultrastructural and mechanical properties; yet these are different from those of in vivo adult muscle and may represent the avian striated muscle archetype expressed in the absence of innervation. Primary or cell line cultures of rat muscle produce far fewer mechanically active fibers than do avian cell cultures. The influence of culture conditions and cell source, whether avian or mammalian, on the extent of differentiation expressed in culture is so great that our understanding of studies on cultured muscle fibers would benefit from some characterization of both morphological and contractile properties of the fibers being used.

Acetylcholine↗
PubMed1977

Management of sudden coronary death.

Twenty-three survivors of out-of-hospital sudden coronary death (SCD) have been followed subsequent to initial hospitalization, cardiac catheterization and coronary angiography, and ultimate coronary revascularization (11 patients) or medical treatment (12 patients). All were treated at the Milwaukee County Medical Center. History of previous myocardial infarction (10 patients) and predominance of triple coronary artery disease (20 patients) with associated ventricular dysfunction (21 patients) demonstrated advanced coronary disease in both groups. Selection for revascularization (mean, 3 grafts per patient) was not randomized, but was based on precarious coronary anatomy and was reinforced by post-SCD ventricular dysrhythmias and angina. During an average follow-up of 13 months, there were 2 perioperative surgical deaths (1 recurrent SCD) and 3 medical deaths (2 recurrent SCDs), giving a mortality rate of 22%. This is an improvement over reported post-SCD natural history and may support a policy of offering revascularization to all SCD patients who have precarious coronary anatomy.

Adult↗
PubMed1976

Problems with balloon-tipped stylet pacemaker catheters.

Balloon-tipped stylet pacemaker catheters have two intraluminal stylet-related limitations that warrant extreme caution in their use. The first limitation involves manipulation of the stylet inside the catheter and appears to be a consequence of the angulation made by the catheter in the right atrium; the second limitation is a complication involving actual in vivo fracture of the stylet and is presumably related to tapering of the stylet at a point of stress in the right atrium. Although these pacemaker catheters have distinct advantages, the problem arising from their use cannot be ignored. Until modification can be made to resolve these problems, this catheter must be used with extreme caution.

Aged↗