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R A Stine

Publications and source records attributed to R A Stine.

9 recordsLinked to original sources
PubMed2001

Non-parametric estimates of overlap.

Kernel densities provide accurate non-parametric estimates of the overlapping coefficient or the proportion of similar responses (PSR) in two populations. Non-parametric estimates avoid strong assumptions on the shape of the populations, such as normality or equal variance, and possess sampling variation approaching that of parametric estimates. We obtain accurate standard error estimates by bootstrap resampling. We illustrate the practical use of these methods in two examples and use simulations to explore the properties of the estimators under various sampling situations.

Acetates↗
PubMed1996

The relationship of developmental narrowing of the cervical spinal canal to reversible and irreversible injury of the cervical spinal cord in football players.

An evaluation of forty-five athletes who had had an episode of transient neurapraxia of the cervical spinal cord revealed a consistent finding of developmental narrowing of the cervical spinal canal. The purpose of the present epidemiological study was to determine the relationship, if any, between a developmentally narrowed cervical canal and reversible and irreversible injury of the cervical cord with use of various cohorts of football players as well as a large control group. Cohort I comprised college football players who were asymptomatic and had no known history of transient neurapraxia of the cervical cord. Cohort II consisted of professional football players who also were asymptomatic and had no known history of transient neurapraxia of the cervical cord. Cohort III was a group of high-school, college, and professional football players who had had at least one episode of transient neurapraxia of the cervical cord. Cohort IV comprised individuals who were permanently quadriplegic as a result of an injury while playing high-school or college football. Cohort V consisted of a control group of male subjects who were non-athletes and had no history of a major injury of the cervical spine, an episode of transient neurapraxia, or neurological symptoms. The mean and standard deviation of the diameter of the spinal canal, the diameter of the vertebral body, and the ratio of the diameter of the spinal canal to that of the vertebral body were determined for the third through sixth cervical levels on the radiographs for each cohort. In addition, the sensitivity, specificity, and positive predictive value of a ratio of the diameter of the spinal canal to that of the vertebral body of 0.80 or less was evaluated. The findings of the present study demonstrated that a ratio of 0.80 or less had a high sensitivity (93 per cent) for transient neurapraxia. The findings also support the concept that symptoms may result from a transient reversible deformation of the spinal cord in a developmentally narrowed osseous canal. The low positive predictive value of the ratio (0.2 per cent) however, precludes its use as a screening mechanism for determining the suitability of an athlete for participation in contact sports. Developmental narrowing of the cervical canal in a stable spine does not appear to predispose an individual to permanent catastrophic neurological injury and therefore should not preclude an athlete from participation in contact sports.

Adolescent↗
PubMed1986

Localization of the site of ventricular premature complexes by radionuclide angiographic phase imaging.

To investigate whether gated radionuclide angiographic phase imaging is useful for visually displaying the origin of ventricular premature complexes (VPCs), 82 patients were studied by gating only VPCs. The VPC "origin" by the scintigraphic method was defined as the area of earliest phase and was compared with that predicted by 12-lead electrocardiographic criteria in all patients and to invasive electrophysiologic mapping in 10. Separating the right ventricle into 3 and the left ventricle into 4 segments, the phase imaging method and the electrocardiographic criteria agreed as to ventricle of VPC origin in 69 patients (84%) and segment of origin within each ventricle in 46 (56%). When baseline ventricular wall motion was analyzed, the 2 methods agreed to the ventricle of VPC origin in 31 of 33 patients (94%) with normal wall motion, 20 of 23 (87%) with segmental wall motion abnormalities and 19 of 26 (73%) with diffuse wall motion abnormalities. Agreement between the 2 methods as to specific segmental localization of the arrhythmia focus was noted in 21 of 33 patients (64%) with normal wall motion, 11 of 23 (48%) with segmental wall motion abnormalities and 12 of 26 (46%) with diffuse hypocontractility. In the 10 patients with endocardial mapping studies, the phase imaging technique confirmed the segment of VPC origin in all 10; the electrocardiographic method was accurate in 8. Thus, gated radionuclide angiographic phase imaging methods may be of value in noninvasively defining the origin of spontaneous VPCs. The visual format allows ready interpretation of the arrhythmia origin, and there may be an advantage to this approach over electrocardiographic morphometric criteria.

Adolescent↗
PubMed1985

Electrophysiologic mechanisms of provoked atrial flutter in mitral valve prolapse syndrome.

To examine the electrophysiologic determinants of provoked atrial flutter (AF) in patients with mitral valve prolapse (MVP), studies were performed in 4 groups of patients: group 1 (n = 5), patients with MVP and AF; group 2 (n = 6), patients without MVP but with AF; group 3 (n = 6), patients with MVP but without AF; and group 4 (n = 5), patients without MVP and without AF. P-wave duration, intraatrial conduction, interatrial conduction and effective refractory periods for both the high right atrium and the low right atrium were longer in group 2 than in group 1. The effective refractory period of the low right atrium was longer in group 3 than in group 1. The interatrial conduction interval was longer in group 2 than in group 4. Thus, in patients without MVP, atrial conduction delay is the predominant determinant of AF, whereas differences in right atrial refractoriness appear to be most important to the provocation of AF in the patient with MVP. These differences in atrial refractoriness may be a result of abnormal autonomic influences in patients with MVP.

Adolescent↗
PubMed1985

Failure of percutaneous transluminal coronary angioplasty to stimulate platelet and prostaglandin activity.

Platelet function and prostaglandin activity were evaluated in nine patients with coronary artery disease undergoing percutaneous left anterior descending coronary artery angioplasty (PTCA) and compared to nine normal controls. Transcoronary measurements (arterial-coronary sinus) of platelet counts, mean platelet volume, platelet factor 4 (PF4), beta thromboglobulin, thromboxane (B2), and 6-keto-PGF 1 alpha were made. When compared to normal controls, the patients with coronary artery disease had higher circulating baseline levels of PF4 in the coronary sinus. There was no transcardiac production of any factor at baseline or immediately after infusion of nitroglycerin or performance of PTCA. These results suggest that PTCA does not grossly alter arachidonic acid metabolism or platelet activity.

6-Ketoprostaglandin F1 alpha↗
PubMed1984

The noninvasive localization of ventricular pacing sites by radionuclide phase imaging.

This study was designed to investigate the potential role of radionuclide angiographic phase imaging in defining ventricular pacing sites. Twenty patients were paced from multiple right ventricular and left ventricular sites. Ten patients had both normal wall motion and normal electrocardiograms (ECGs), while 10 patients had segmental wall motion abnormalities and/or bundle branch block. Both continuous pacing and premature ventricular stimuli were performed. Multiple (two to three) views of each pacing site were obtained by radionuclide angiography and the ventricular site was determined by subsequent phase imaging. Simultaneous 12-lead ECGs were also obtained. The phase-imaging technique accurately localized all 35 right ventricular and 21 of 25 (84%) left ventricular sites to a specific segment. Statistically, this localization ability was independent of baseline wall motion or conduction system disease. In addition, sites as close as 1.5 cm were identified. The 12-lead ECG distinguished left ventricular from right ventricular pacing sites in all patients. Segmental localization by ECG in the right ventricle was accurate in 24 of 35 (69%) and in the left ventricle in 17 of 25 (68%). Thus, radionuclide angiographic phase imaging provides excellent descriptive information regarding the focus of ventricular pacing ectopy and can define both sites of continuous pacing and intermittent premature ventricular stimulation. These findings provide a basis for further assessment of the role of phase imaging in the evaluation of patients with spontaneous ventricular ectopy.

Bundle-Branch Block↗
PubMed1984

Indocyanine green clearance following single and chronic cimetidine doses.

Twenty-five indocyanine green (ICG) clearance determinations were performed in four subjects in the presence of quinidine or propranolol before and after one week of treatment with cimetidine, 1200 mg/day, and following a single 600 mg cimetidine dose. There was no significant difference between the mean ICG clearance before cimetidine treatment and that after one week of therapy with cimetidine, while the mean ICG clearance was 25% lower following single cimetidine doses (p greater than 0.05). It is concluded that cimetidine has only a transient hepatic blood flow lowering effect.

Adult↗
PubMedDate not supplied

Age at menarche based on recall information.

Censored likelihood methods which use recalled dates yield accurate estimates of the age at menarche in an urban population of black adolescent girls. The mean age at menarche is 12.44 (SE 0.08) years for a sample of 272 black adolescents in Philadelphia, PA. The methodology we describe is more efficient than logit or probit methods, which are not designed to utilize recall information. Alternative methods which use recall are biased if subject memory is influenced by length of time since menarche. Our methods also provide information on the nature of subject recall that may be useful in further analysis.

Adolescent↗