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Biomedical subjects

R M Boyle

Publications and source records attributed to R M Boyle.

18 recordsLinked to original sources
PubMed1990

Assessing the efficacy of azaprophen and physostigmine as a pretreatment for soman-induced incapacitation in guinea pigs by response-surface modeling.

Physostigmine (PHY) has the advantage over pyridostigmine of minimizing OP-induced incapacitation because it penetrates into the CNS. However, physostigmine is behaviorally toxic at relatively low concentrations. It is anticipated that this could be offset by a cholinolytic to prevent behavioral deficit due to the carbamate pretreatment alone. The therapeutic efficacy of physostigmine/azaprophen pretreatment therapy was evaluated in soman-challenged guinea pigs. Response surface methodology was employed to describe the relationship of the pretreatment combination with duration of incapacitation. The significance of the combination relative to PHY alone was evaluated in addition to dose combinations that yield optimal time to recovery. Analysis of the fitted response surface indicated that combination pretreatment with these compounds significantly reduces the time to recovery after soman challenge versus pretreatment with PHY alone.

Animals↗
PubMed1990

Masking procedure, randomization and stratification, and compliance monitoring in the Growth Failure in Children with Renal Diseases Study.

Ensuring the integrity of a study such as the GFRD Study requires close cooperation among all groups involved with the study and the patient. Many factors may influence the outcome and validity of a multicenter, double-masked, randomized trial. Any dosage modifications that may need to be made rely totally on established communication between the centers, the DCC, and the Core Pharmacy. When the procedures outlined above are followed, masking is ensured and patient compliance can be measured.

Calcitriol↗
PubMed1990

Data coordination and management in the Growth Failure in Children with Renal Diseases Study.

The DDC of the GFRD Study works closely with the Administrative Core and with all participating clinical centers to ensure the timely collection of accurate, reliable, and complete data. The development and maintenance of a data-base management system, including continuous monitoring of all data, represent primary responsibilities of the DCC. Coordination and communication tasks in the multicenter study have been challenging but rewarding. Proper planning and positive attitudes have enhanced the effectiveness of the DCC throughout this clinical trial.

Anthropometry↗
PubMed1990

Malignant thymoma causing tricuspid valve obstruction.

A 57-year-old man presenting with a retrosternal mass was found to have a malignant thymoma. This was treated with surgery and radiotherapy. It recurred 5 years later as an intra-cardiac mass causing tricuspid valve obstruction.

Heart Valve Diseases↗
PubMed1988

Comparison between manual and computer measurement of ST-segment amplitude during exercise.

Several studies have shown that the maximal ST/HR slope may be used as a reliable index of myocardial ischemia as assessed by coronary angiography, but this involves laborious training and derivation, particularly with respect to the measurement of ST segment amplitude, which is obtained by averaging values measured in at least 10 cardiac cycles in the steady state. The authors compared manual measurement of ST-segment amplitude with computer-processed beat using cardiac cycles in six consecutive patients with standard 12-lead records obtained over 5 seconds and a beat processed by the recorder to represent each lead (modal beat, over 10 seconds). All recordings were made in the steady state. Two patients had myocardial ischemia, as assessed by means including the maximal ST/HR slope and the occurrence of ST-segment depression at the end of exercise. Comparisons were made between measurements in 324 pairs of ST-segment amplitude obtained, respectively, from manually averaged recorded beats (average beat) and the modal beat during each step of the exercise test. The level of the ST-segment, (80 msec after the end of QRS complex) was independently obtained from the two records in a blinded fashion. The group data showed that the modal beat gave significantly lower values of ST-segment amplitude than the average beat. Similar results were obtained when 286 pairs of positive amplitudes were compared in the range of 0-7.25 mm. In the remaining 38 pairs in which ST-segment depression was found, the amplitude in the modal beats was not significantly different from the average beats.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Changes in myocardial ischaemia during isosorbide dinitrate or indoramin therapy in patients with stable angina using relations between the ST segment and heart rate.

The effect of isosorbide dinitrate or indoramin on myocardial ischaemia was examined in patients with stable angina pectoris. In a prospective trial, randomization resulted in 8 and 9 patients, respectively, given isosorbide dinitrate in a dose of 30-90 mg daily, and indoramin in a dose of 75-225 mg daily; 2 of these patients were serially examined during the two types of therapy. Changes in myocardial ischaemia were assessed by exercise testing using 12 standard electrocardiographic leads and a bipolar lead CM5. Individual and group comparisons showed that isosorbide dinitrate resulted in an increase in ST segment depression, the maximal ST/heart rate slope and the ratio of net ST segment depression to increases in heart rate (at least P less than 0.01). In contrast, with indoramin therapy there were no significant changes in these indices. The results in these patients suggest that isosorbide dinitrate leads more consistently to increases in the severity of myocardial ischaemia than indoramin, although this effect on ischaemia is apparently less than the benefit of these agents on exercise performance.

Adult↗
PubMed1988

Aortic valve disease and the ST segment/heart rate relationship: a longitudinal study before and after aortic valve replacement.

The ST segment/heart rate relationship or maximal ST/HR slope has been validated as an index of myocardial ischemia in selected populations of patients with angina pectoris. The present study involved patients selected as having aortic valve disease unaccompanied by angiographic coronary artery narrowing. In each of seven patients, so far examined, a slope value and ST segment depression of greater than 1 mm were obtained which, according to previous experience, indicated myocardial ischemia equivalent to coronary heart disease. After aortic valve replacement, there was a significant reduction in heart size as assessed using the cardiothoracic ratio, and the amplitude of QRS complex on the electrocardiogram. The slope was abolished (two patients) or markedly reduced (five patients), and the decrease in the seven patients was statistically significant. ST segment depression could be obtained in one patient. This study has shown the occurrence of maximal ST/HR slope in patients without large coronary artery disease who have aortic valve disease and cardiac enlargement.

Aortic Valve↗
PubMed1987

Use of the maximal ST/HR slope to estimate myocardial ischaemia after recent myocardial infarction.

Fifty two patients were examined 4-6 weeks after myocardial infarction to assess whether factors other than coronary artery narrowing affect the maximal ST/HR slope which is used as an index of myocardial ischaemia. The slope was compared with indices of myocardial scarring or cardiac enlargement derived from x ray and echocardiographic and angio-cardiographic investigations. In 35 (67%) patients the slope failed to predict the severity of myocardial ischaemia attributable to coronary artery narrowing: in 14 (27%) patients the slope overestimated the findings of coronary angiography and in 21 (40%) patients the slope underestimated the findings of coronary angiography. In the remaining 17 (33%) patients the slope accorded with the assessment of myocardial ischaemia by coronary angiography. Underestimation by the slope was associated with significantly poorer left ventricular function and a lower ejection fraction, indicating a greater degree of myocardial scarring. To assess whether overestimation was related to cardiac enlargement with better preservation of ventricular function a follow up examination was performed six months after infarction. In the overestimated group 11 patients were followed up and seven of them showed a reduction in the maximal ST/HR slope which correlated with a reduction in the cardiothoracic ratio. This suggested that cardiac enlargement had contributed to myocardial ischaemia. The results suggest that if the maximal ST/HR slope is an index of exercise induced myocardial ischaemia after recent infarction, it is subject to the influences of coronary artery narrowing as well as those of scarring and cardiac enlargement.

Adult↗
PubMed1987

Diagnostic value of the maximal ST segment/heart rate slope in asymptomatic factory populations.

In Leeds in hospital populations of patients with angina the maximal ST/HR slope was found to be a reliable index of myocardial ischemia as assessed by coronary angiography. Subsequent studies in Leeds and elsewhere in populations of patients with cardiac enlargement or following myocardial infarction have shown that the slope is affected by myocardial scarring, ventricular enlargement and aneurysm. These findings implied that the slope had features in common with other usual exercise tests; studies in Leeds and elsewhere, however, have shown a superior diagnostic reliability using the maximal ST/HR slope in patients with angina. The present report involves the use of the slope in asymptomatic populations. Trials are being undertaken in two factory populations, which respectively comprised all volunteers or asymptomatic men over the age of 30 who were randomly chosen by computer. Subjects with slope values indicating, according to previous experience, myocardial ischemia equivalent to coronary heart disease were referred for cardiological investigations which included angiocardiography; blind comparisons were performed between results of investigations and the slope. So far 1194 subjects have been examined. In 68 subjects the maximal ST/HR slope indicated myocardial ischemia, and in 24 of these cardiological investigations were completed. In nine of the 24 subjects the slope corresponded to the number of significantly narrowed coronary arteries (greater than 75% reduction in luminal diameter); in 12 of the remaining 15 subjects who had no coronary narrowing, there were cardiac lesions which included cardiac enlargement, aortic valve disease, myocarditis, pericarditis, myocardial bridging and conduction defects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1979

An analysis of returning patients in family practice.

Morbidity records from eight practices participating for three years in the Virginia Family Practice Data System are analyzed with respect to two mutually exclusive groups of patients: those who return from one year to the next and those who do not return. Initially, substantial interpractice variation in patient return rates is presented, and age and sex characteristics of these patients are examined. The data indicate that approximately 40 percent of patients visiting the practice in one year return in the next, 25 percent return in each of two subsequent years, and only 12 percent return two years hence. Returning patients are found to be significantly older and more likely to be female than non-returning patients. These two groups of patients are then compared in terms of recorded morbidity and workload rates. Specific categories of problems, such as Diseases of the Circulatory System, are associated with returning patients. This paper thus presents empirical evidence which supports common assumptions concerning patients and problems seen in family practice.

Adult↗
PubMed1979

Implementing a multiphased hospice program.

By implementing a hospice program in three phases, each of which can be integrated with existing services in general acute care and long-term care facilities, a health care institution can provide the community with an important new service. And the parent organization incurs only the cost or providing additional inservice and medical education.

Day Care, Medical↗
PubMed1978

Family practice in Virginia: a comparative analysis of two years' data.

Data representing Fiscal Years 1975 and 1976 as well as the aggregate 1975--1976 data set are reviewed in this paper. Information on 92,410 discrete patients and the 333,709 transactions they generated is studied. The transactions per patient rate of 3.6 varies greatly among the eight practices under investigation. This interpractice variation is complemented by remarkable year-to-year consistency within each practice. Age and the percent of continuing patients are presented as possible explanations for this variation. These data are useful to the physician in identifying the high-use patients and to the health planner for manpower and funding appropriations.

Adolescent↗
PubMed1977

The Age/Sex Register: estimation of the practice population.

Determination of the number of patients served by a family practice is important for health services delivery and research. A sound estimate of the practice population should enhance the patient management responsibilities of the family physician. This methodology uses the Age/Sex Register to provide a series of estimations of a "teaching" unit population. Results of a sample survey indicate that 21.3% of "inactive patients" (those who have not received services from the practice in two years) still consider themselves under the care of the practice. Replication of this approach is suggested for other practices to improve planning and resource allocation.

Age Factors↗