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Steven Bailey

Publications and source records attributed to Steven Bailey.

8 recordsLinked to original sources
PubMed2006

Impact of physiological variables and genetic background on myocardial frequency-resistivity relations in the intact beating murine heart.

Conductance measurements for generation of an instantaneous left ventricular (LV) volume signal in the mouse are limited, because the volume signal is a combination of blood and LV muscle, and only the blood signal is desired. We have developed a conductance system that operates at two simultaneous frequencies to identify and remove the myocardial contribution to the instantaneous volume signal. This system is based on the observation that myocardial resistivity varies with frequency, whereas blood resistivity does not. For calculation of LV blood volume with the dual-frequency conductance system in mice, in vivo murine myocardial resistivity was measured and combined with an analytic approach. The goals of the present study were to identify and minimize the sources of error in the measurement of myocardial resistivity to enhance the accuracy of the dual-frequency conductance system. We extended these findings to a gene-altered mouse model to determine the impact of measured myocardial resistivity on the calculation of LV pressure-volume relations. We examined the impact of temperature, timing of the measurement during the cardiac cycle, breeding strain, anisotropy, and intrameasurement and interanimal variability on the measurement of intact murine myocardial resistivity. Applying this knowledge to diabetic and nondiabetic 11- and 20- to 24-wk-old mice, we demonstrated differences in myocardial resistivity at low frequencies, enhancement of LV systolic function at 11 wk and LV dilation at 20-24 wk, and histological and electron-microscopic studies demonstrating greater glycogen deposition in the diabetic mice. This study demonstrated the accurate technique of measuring myocardial resistivity and its impact on the determination of LV pressure-volume relations in gene-altered mice.

Animals↗
PubMed2005

Evaluation of the L2 spinal nerve root infiltration as a diagnostic tool for discogenic low back pain.

BACKGROUND: To assess whether unilateral L2 infiltration with local anesthetic can be used to identify patients who will have negative discograms and thus eliminate the need for the discogram. Discogenic low-back pain is considered to have afferent pathways in the sinuvertebral nerves, mainly originating from the ventral rami of the spinal nerves. There is evidence that pain arising from the lower lumbar intervertebral discs may be transmitted through the sympathetic afferent fibers contained in the L2 spinal nerve root. Provocative discography, within the context of other clinical data, is the current "gold standard" by which to diagnose discogenic low-back pain, but a far more invasive procedure than L2 infiltration. OBJECTIVE: To evaluate the correlation between unilateral second lumbar (L2) spinal nerve root infiltration with local anesthetic and provocative discography in patients with chronic low back pain. STUDY DESIGN: A prospective, observational study. METHODS: All patients scheduled for discography were asked to participate in having local anesthetic infiltration of the L2 spinal nerve root at least two weeks prior to discography, until forty subjects were enrolled. Discography was performed after the patient's pain level returned to baseline. RESULTS: Local anesthetic infiltration of the L2 spinal nerve root was predictive of provocative discography results in only 46.5% of the subjects (26% true positives, and 20.5% true negatives). In 53.5% of the subjects, L2 infiltration was not predictive of discography results (20.5% false positives, and 33% false negatives). CONCLUSIONS: The results showed that unilateral L2 infiltration is not predictive of discogenic low-back pain when compared to discography, the current "gold-standard" for diagnosis.

Journal Article↗
PubMed2003

Evaluation of glycoprotein IIb/IIIa inhibitors in carotid angioplasty and stenting.

PURPOSE: To review the immediate neurological and bleeding complications associated with the use of glycoprotein (GP) IIb/IIIa inhibitors in patients undergoing extracranial carotid artery stent placement. METHODS: A retrospective review was performed of 550 patients (321 men; mean age 71.1 years, range 28-91) who underwent carotid artery angioplasty and stent placement. Glycoprotein IIb/IIIa inhibitors were given prophylactically along with heparin to 216 patients, whose outcomes were compared to a control group of 334 patients who received intravenous heparin alone. Primary endpoints were the immediate and 30-day neurological complications, including transient ischemic attacks (TIAs), minor and major strokes, and neurologically-related deaths. The secondary endpoint was any abnormal bleeding. RESULTS: The all stroke/neurological death rate in 216 patients treated with heparin and GP IIb/IIIa inhibitors was 6.0% (13 events) compared 2.4% (8 events) in the 334 patients in the heparin-only control group (p=0.0430). Two of the 4 neurologically-related deaths in the GP IIb/IIIa inhibitor group resulted from intracranial hemorrhages; there were no intracranial hemorrhages in the heparin-only group. There was 1 episode of extracranial bleeding in the GP IIb/IIIa inhibitor group treated with embolization. The incidences of significant puncture-site bleeding requiring transfusion were similar in the groups. CONCLUSIONS: Neurological complications following percutaneous carotid artery interventions have been relatively few. The neurological sequelae in carotid stent patients receiving glycoprotein IIb/IIIa inhibitors were more numerous and consequential, which suggests that the use of GP IIb/IIIa inhibitors in carotid stenting should be discouraged.

Abciximab↗
PubMed2002

Influence of stent design and material composition on procedure outcome.

Although intravascular stents have received widespread application, significant limitations remain. In stent restenosis, the most pervasive problem affecting stents, is related in part to technical aspects of the device. Design features of the stent that influence outcome have been identified and optimized for improved performance. The influence of stent materials on critical aspects of healing, such as thrombotic, inflammatory, and hyperplastic responses, are less well understood. For this reason, significant progress in this area is lacking. Current stents have significant contamination with industrial impurities on the surface and in the bulk. This fact adds to the difficulties in interpreting the biologic reaction of the host to the device. Better understanding of the basic biologic interactions is the path to significant improvement.

Biocompatible Materials↗