Gun control.
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Attitude of Health Personnel↗
Biomedical subjects
B J Kane
Publications and source records attributed to B J Kane.
Can atherosclerotic coronary arteries vasodilate? An intraoperative high-frequency epicardial echocardiographic study.
Our purpose was to evaluate the vasodilating responses of atherosclerotic coronary arteries using intraoperative high-frequency (12 MHz) epicardial echocardiography. We obtained continuous high-frequency epicardial echocardiographic recordings during surgery, and determined cross-sectional lumen area from 17 coronary arterial segments (12 patients). Nitroglycerin (100 to 400 micrograms/min) was administered intravenously to reduce mean (+/- SEM) arterial pressure 14 +/- 1.8 mm Hg. The cross-sectional arterial images were classified using 3 different parameters: arterial lumen area, percentage of the arterial wall circumference that was atherosclerotic (wall thickness > 0.7 mm), and presence of an eccentrically shaped arterial lumen (maximal/minimal luminal diameter > 1.5). Nine arterial segments had small (< 5.0 mm2) arterial lumens (1.7 +/- 0.40 mm2 [+/- SEM; range 0.6 to 3.9]). With nitroglycerin, the luminal area increased 0.8 +/- 0.28 mm2 (range 0 to 2.5), and 39 +/- 12.1% (range 0 to 117). The remaining 8 segments had larger (> 5.0 mm2) lumens (8.7 +/- 0.91 mm2 [range 5.0 to 11.9]). With nitroglycerin the luminal area increased 4.3 +/- 1.11 mm2 (range 1.4 to 11.4), and 51 +/- 10.2% (range 16 to 96). Seven arterial segments had eccentric lumens; mean maximal/minimal ratio was 1.8 +/- 0.08 (range 1.6 to 2.0). The area increased 39 +/- 7.3% (range 16 to 71) with nitroglycerin. In the 10 concentrically shaped lumens (maximal/minimal lumen diameters 1.3 +/- 0.04 [range 1.1 to 1.5]), nitroglycerin increased luminal area by 48 +/- 12.6% (range 0 to 117) (p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)
Coronary Artery Disease↗
Aminophylline for methotrexate-induced neurotoxicity.
Methotrexate, a mainstay treatment for children with acute lymphoblastic leukaemia, can cause neurotoxicity, with paralysis, seizures, somnolence, anorexia, and headaches. The pathophysiology of this reaction is unknown. It has been suggested that the anti-inflammatory effect of methotrexate in patients with arthritis is due to adenosine release brought on by inhibition of purine synthesis. Since adenosine is a central nervous system depressant, we wondered whether adenosine release in the central nervous system could account for some of the neurotoxicity due to methotrexate, and whether that toxicity could be lessened by displacement of adenosine from its receptor by aminophylline. 6 patients (age 3-16 years) who had methotrexate-induced neurotoxicity unresponsive to standard treatment received 2.5 mg/kg aminophylline. In addition, the concentration of adenosine in the cerebrospinal fluid (CSF) from 11 children completing a 24-h systemic methotrexate protocol was compared with that in 8 newly diagnosed patients and 12 who had not received any treatment for at least a week. 4 of 6 patients with toxic signs and symptoms attributed to methotrexate and unrelieved by steroids, epidural blood patch, promethazine, 5-hydroytryptamine antagonists, paracetamol, and narcotics, had complete resolution of neurotoxicity after or during a 1-h infusion of aminophylline; 2 others had a pronounced improvement but persistent nausea. CSF adenosine concentrations of patients receiving methotrexate, even when there was very slight or no toxicity, were greatly increased compared with control subjects (mean values of 217 and 51 nmol/L, median 175 and 52 nmol/L). Subacute methotrexate neurotoxicity may be mediated by adenosine and relieved by aminophylline.
Adenosine↗
Force-sensing microprobe for precise stimulation of mechanosensitive tissues.
Quantitative study of the transduction mechanisms in mechanically sensitive nerve terminals has been impeded by the lack of instrumentation with which to generate precisely controlled, physically localized mechanical stimuli. We have developed high-resolution force sensing mechanical microprobes for use in the characterization of such nerve terminals. This paper describes their design, fabrication, and testing. A microprobe is comprised of a 0.5- to 2-mm long silicon cantilever beam projecting from a larger supporting silicon substrate. Acting as the variable leg of a Wheatstone bridge circuit, a piezoresistive polysilicon element located at the base of the beam is used to measure the stimulation force applied at the tip. The microprobes exhibit a stable, linear relationship between the stimulation force and the resulting output voltage signal. Stimulation forces up to 3 mN have been generated with a measurement resolution of 10 microN. These microprobes have been used as the force sensing element of a closed loop feedback-controlled stimulation system capable of stimulating the mechanoreceptive nerve terminals of the rabbit corneal epithelium.
Animals↗
In vivo assessment of nonlinear myocardial deformation using finite element analysis and three-dimensional echocardiographic reconstruction.
In vitro data have shown that the myocardium exhibits nonlinear passive stress-strain relationship and a non-linear pressure-volume relationship. A finite element (FE) analysis and optimization algorithm was used on three-dimensional reconstructed left ventricular (LV) geometry using echocardiographic images, along with hemodynamic measurements, in seven closed-chest dogs to show a nonlinear stress-strain relationship in vivo. Our analysis included the computation of Poisson's ratio from the measured volumetric strain of the myocardium and a simulated pericardial pressure load ("equivalent pericardial pressure") applied to the epicardial surface of the reconstructed LV. LV geometry was reconstructed in three or four incremental time steps in diastasis and the myocardium was assumed to be homogeneous, isotropic, and linearly elastic during these short intervals in this initial study. Simultaneous LV chamber pressure and equivalent pericardial pressure were incorporated into the algorithm to predict actual LV expansion. Computations were performed iteratively at each interval to compute the optimized elastic modulus. By performing the FE analysis and optimization at each interval (a step-wise linear analysis approach), a linear relationship between the myocardial elastic modulus and LV chamber pressure was derived (r = .87 to .98). Such a linear relationship is equivalent to an exponential myocardial stress-strain relationship in vivo. Detailed measurement of nonhomogeneous regional deformation are becoming possible with the advent of sophisticated imaging techniques. The methodology described in this study, with appropriate modifications in the FE analysis and optimization algorithms, can be applied to assess the complex three-dimensional pressure-deformation characteristics in vivo.
Algorithms↗
Doppler catheter tip localization using color enhancement.
The objective of this research was to determine if the ultrasound emissions of the Doppler catheter can be used to locate its position in 3 dimensions by conventional echocardiography. A Doppler catheter has previously been shown to permit nonfluoroscopic retrograde catheterization of the aortic root and left ventricular chamber by using velocity waveform polarity for directional guidance. A significant difficulty in providing ultrasound catheter guidance, however, has been the inability to recognize the Doppler catheter tip, because each point at which a flexible catheter crosses the image plane can be misinterpreted as the catheter tip. Initial in vitro water bath trials were performed using the Doppler catheter attached to a standard velocimeter. Using a 5 MHz imaging transducer and color Doppler methods, the presence or absence of a banded color pattern which could demarcate the Doppler catheter tip was recorded at various angles in and out of the scanning plane. Using Doppler retrograde guidance and transesophageal echocardiography, color Doppler banded patterns, which could identify the Doppler catheter tip, were investigated in the dog aorta. In order to understand the physical mechanisms involved, a series of water bath trials were then conducted using the Doppler catheter attached to a velocimeter which was synchronized to the echo machine. Initial nonsynchronized water bath trials revealed distinct banded color patterns demarcating the Doppler catheter tip when it pointed in any direction within the beam width, except for a 40 degrees blind cone directly away from the imaging transducer.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Arterial imaging with a new forward-viewing intravascular ultrasound catheter, I. Initial studies.
BACKGROUND: Intravascular ultrasound (IVUS) of arteries is limited by the inability of current instruments to visualize beyond the catheter tip. We have developed a prototype 4-mm-diameter forward-viewing IVUS catheter (Cardiovascular Imaging Systems, Sunnyvale, Calif) that has the ability to provide B-mode cross-sectional ultrasound data for a distance of up to 2 cm distal to the catheter tip. METHODS AND RESULTS: To study the utility of this device, a 20-MHz forward-viewing IVUS catheter was used to examine 13 arterial segments (5 human femoral arteries, 1 human carotid artery, 7 canine arteries) in vitro and 1 phantom. After imaging, all data were compared with histology (Histo). In all cases, the IVUS catheter provided forward-viewing images corresponding to the arterial geometry and demonstrated vascular landmarks and atherosclerotic lesions. There was a good correlation between Histo-determined luminal diameters (LD) and IVUS-determined diameters for a distance of 14 mm ahead of the catheter tip: IVUS LD = 1.0 Histo LD + 1.3 (r = .87). CONCLUSIONS: These preliminary data suggest that a forward-viewing IVUS catheter is feasible, accurate, and useful for evaluation of arterial geometry distal to the catheter tip.
Angiography↗
Arterial imaging with a new forward-viewing intravascular ultrasound catheter, II. Three-dimensional reconstruction and display of data.
BACKGROUND: Current intravascular ultrasound (IVUS) catheters provide transverse imaging at the level of the ultrasound transducer. This limits imaging to large-diameter segments without critical atherosclerotic narrowings. We have developed a prototype 20-MHz forward-viewing IVUS catheter that provides two-dimensional sector imaging distal to the catheter tip. A present limitation of this technique is that the catheter must be manually rotated to obtain multiple longitudinal views required to integrate the segment into a three-dimensional matrix. To overcome this, we have developed an algorithm that reconstructs these multiple two-dimensional forward-viewing IVUS images into a three-dimensional matrix for more complete depiction of the segment distal to the ultrasound catheter. This algorithm allows display and multidimensional slicing of the three-dimensional reconstruction. METHODS AND RESULTS. To test our algorithms, five arterial segments (three canine aortas, two human femoral arteries) were evaluated in vitro. In each segment, 36 forward-viewing longitudinal slices were collected, digitized, processed, and reoriented to produce a three-dimensional reconstruction (3DR) matrix. The matrix data were sliced into parallel transverse sections and compared with morphometric interpretation of histological sections (Histo). As a result, image data could be reconstructed for a distance of 2.0 cm ahead of the catheter. 3DR easily demonstrated wall and luminal morphology and provided transverse IVUS images comparable to the histological specimens. A good correlation was noted between Histo- and 3DR-determined luminal diameters (LD) and luminal areas: 3DR LD = 1.4 Histo LD-0.4, r = .86; 3DR LD = 0.7 +/- 0.20 cm (mean +/- SD); and Histo LD = 0.7 +/- 0.13 cm. CONCLUSIONS: These preliminary data demonstrate the feasibility of 3DR of forward-viewing IVUS data. This method allows rapid, detailed analysis of diseased arterial segments previously unavailable with standard IVUS and may permit better targeting of interventional techniques.
Animals↗
General and specific psychotherapy role induction with substance-abusing clients.
The present study examined the effects of general and specific psychotherapy role induction on return rates and attendance in psychotherapy for substance-abusing clients. The subjects were 111 of 129 consecutive applicants to a community outpatient drug treatment center. Following a standard intake interview, clients received either a general psychotherapy role induction or a drug treatment specific role induction, or were placed in one of two control conditions. Results indicated that clients who received role induction procedures were more likely than controls to return after the intake interview. Furthermore, clients who received the drug treatment specific role induction returned at a significantly higher rate than all other clients. Analysis of attendance rates after 3 months showed that role induction had no effect on continuation in treatment.
Adolescent↗
A peer-tutored, instructional management program in computational mathematics for incarcerated, learning disabled juvenile delinquents.
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Adolescent↗
Pentostatin: an adenosine deaminase inhibitor for the treatment of hairy cell leukemia.
OBJECTIVE: To review the pharmacology, pharmacokinetics, adverse effects, and various dosage regimens of pentostatin, and to evaluate the role of pentostatin in the treatment of hairy cell leukemia (HCL). DATA IDENTIFICATION: Articles were identified via an English-language literature search of MEDLINE (1966-91) and an extensive search of bibliographies from identified articles. STUDY SELECTION: Human clinical trials and case reports were selected for evaluation. DATA EXTRACTION: The literature was assessed for quality, methodology, and outcome information. DATA SYNTHESIS: At dosages of 4 mg/m2 administered every other week for 6-9 months, pentostatin has been shown to successfully induce a complete response in 58-90 percent of patients and to produce a partial response in up to 30 percent of patients with HCL. The median time to achieve a response is 4.7 months. Long-term remissions of at least 14 months' duration have occurred in some patients. Compared with interferon alfa alone, total response rates are not significantly different when pentostatin and interferon alfa are used in combination. When dosed appropriately, pentostatin is generally well tolerated. Common adverse effects include nausea, vomiting, myelosuppression, fever, and infection. CONCLUSIONS: Pentostatin is a purine analog that inhibits adenosine deaminase, a key enzyme necessary for purine salvage. Pentostatin has received labeling approval for the treatment of HCL refractory to a minimum of three to six months of treatment with interferon alfa. Based on current data, pentostatin will be a useful addition to the therapeutic agents presently available to patients with HCL. Ongoing trials are evaluating the effectiveness of pentostatin as first-line therapy for patients with HCL.
Adenosine Deaminase Inhibitors↗