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Biomedical subjects

J R Beck

Publications and source records attributed to J R Beck.

At least 109 records · Page 6Linked to original sources
PubMed1983

Clinical and morphologic cardiac findings after anthracycline chemotherapy. Analysis of 64 patients studied at necropsy.

The relation between clinical evidence of and histologic signs of anthracycline cardiotoxicity was evaluated by reviewing the clinical and morphologic findings in 64 patients studied at necropsy, all of whom had received doxorubicin or daunorubicin chemotherapy during life. Of the 64 patients, 20 (31%) had documented clinical toxicity consisting of impaired left ventricular systolic performance; in 7 (35%) of these 20 patients, histologic signs of toxicity were absent. In the remaining 13 patients with clinical toxicity, histologic signs of toxicity ranged from mild to severe. Of the 44 (69%) patients without clinical signs of drug toxicity, 21 (48%) had no histologic sign of cardiotoxicity; in 23 (52%) of the patients without clinical toxicity, however, morphologic signs of cardiotoxicity were nevertheless present--mild in most patients, but extensive in 4. Signs of extensive histologic toxicity (19 [30%] of 64 patients) were associated with large doses (greater than 450 mg/m2) of the drug, mediastinal irradiation, and age greater than 70 years. This study suggests that attempts to monitor cardiotoxicity by serial evaluation of cardiac histology in patients undergoing anthracycline chemotherapy may be seriously limited by the fact that clinical evidence of toxicity may be present without histologic signs of toxicity; likewise, histologic signs of anthracycline toxicity may be present without clinical evidence of toxicity.

Adolescent↗
PubMed1983

The Markov process in medical prognosis.

The physician's estimate of prognosis under alternative treatment plans is a principal factor in therapeutic decision making. Current methods of reporting prognosis, which include five-year survivals, survival curves, and quality-adjusted life expectancy, are crude estimates of natural history. In this paper we describe a general-purpose model of medical prognosis based on the Markov process and show how this simple mathematical tool may be used to generate detailed and accurate assessments of life expectancy and health status.

Anticoagulants↗
PubMed1982

A convenient approximation of life expectancy (the "DEALE"). I. Validation of the method.

The physician developing a treatment plan for a particular patient often needs to know the life expectancy associated with the outcomes of therapeutic choices. Currently available methods for estimating life expectancy are cumbersome and of limited clinical use. We describe a simple approximation of life expectancy (the "DEALE") that is based on the assumption that survival follows a simple declining exponential function. In this approach, the reciprocal of the age-, sex-, and race-adjusted life expectancy is used to estimate the mortality rate of a healthy person. The life expectancy of a person who also has one or more diseases is obtained by adding disease-specific mortalities to the age-, sex-, and race-adjusted mortality rate and taking the reciprocal of that sum. In this paper we show that this approximation estimates life expectancy accurately for the great majority of clinical problems.

Adult↗
PubMed1982

A convenient approximation of life expectancy (the "DEALE"). II. Use in medical decision-making.

We show how to use a bedside approximation of life expectancy in quantitative decision-making. This method, the declining exponential approximation of life expectancy (DEALE), enables the physician to collate various survival data with information on morbidity to determine a quality-adjusted expected survival for a potential management plan. The keystone in the DEALE approach is the approximation of survival by a simple exponential function. This approximation makes it possible to translate data from various literature sources (life expectancy tables, five-year survival rates, survival curves, median survival) into a single, unified mortality scale. In this paper, we use the DEALE method to obtain approximations of quality-adjusted life expectancy and illustrate the application of the method in a quantitative analysis of a clinical decision.

Aged↗
PubMed1982

Effect of exercise on erythrocyte count and blood activity concentration after technetium-99m in vivo red blood cell labeling.

We studied the effect of exercise on blood radiotracer concentration after technetium-99m in vivo red blood cell labeling. After red blood cell labeling, 13 subjects underwent maximal supine bicycle exercise. Radioactivity, analyzed with a well counter, was measured in heparinized venous blood samples drawn at rest and during peak exercise. Changes in activity were compared with changes in erythrocyte count. Activity and erythrocyte counts increased during exercise in all 13 subjects. Percent increase in activity correlated with percent increase in erythrocyte count (r = -0.78), but did not correlate with either duration of exercise or maximal heart rate. Twenty minutes after termination of exercise, activity and erythrocyte count had decreased from peak exercise values but remained higher than preexercise values. In nine nonexercised control subjects, samples drawn 20 minutes apart showed no change in activity or in erythrocyte count. We conclude that exercise increases blood activity, primarily because of an increase in erythrocyte count. During radionuclide ventriculography, blood activity must be measured before and after any intervention, particularly exercise, before a change in left ventricular activity can be attributed to a change in left ventricular volume.

Adult↗
PubMed1981

Chronic granulocyte leukemia with respiratory distress. Efficacy of emergency leukapheresis.

In the absence of preexisting pulmonary disease, progressive respiratory failure caused by leukostasis associated with uncontrolled chronic granulocytic leukemia developed in two patients. The conditions of both patients improved dramatically with aggressive leukapheresis. Clinical improvement correlated with decreased pulmonary wedge pressure, while vascular volume remained constant. Continuous-flow cell separation removed numerous immature myeloid cells, replaced them with oxygen-carrying erythrocytes, and maintained a constant blood volume. The course of these two patients demonstrates the use of continuous-flow leukapheresis in an intensive care unit to reduce leukocyte count and manifestations of leukostasis rapidly, while improving the oxygen-carrying capacity of blood, without exposing the patients to dangerously large shifts in fluid volume.

Emergencies↗
PubMed1981

The "iron screen": modification of standard laboratory practice with data analysis.

Multivariate analysis was applied to iron deficiency anemia to generate an efficient sequence of diagnostic laboratory tests. A three step diagnostic system--serum ferritin level and mean corpuscular volume as a screen in all patients, followed by serum iron level and total iron binding capacity in some patients, and by erythrocyte sedimentation rate in a few patients--was constructed using a previously validated data reduction system. When compared to bone marrow iron stores, this system was found to have 96 per cent accuracy. In one year of clinical trial the "iron screen" classified 396 of 416 patients in a hospital setting. This sequential strategy shows how clinical laboratory data can be utilized to render diagnoses of defined probability.

Anemia, Hypochromic↗
PubMed1980

A multivariate approach to laboratory practice.

The application of multivariate statistical technics to laboratory data analysis is a recent development in clinical pathology. The proliferation in number and type of diagnostic tests requires a simple method to extract predictors of clinical states from data generated by existing laboratory procedures, as well as a method to assess the usefulness of new tests as they are proposed. A series of algorithms can select a "best predictor" subset of laboratory tests and verify this reduced group's predictive diagnostic worth. The established predictive ability of existing laboratory tests can serve as a reference scale when a newly available laboratory test is evaluated. The proposed new test is included with the best predictors already identified and confirmed. In multivariate analysis the usefulness of the proposed new procedure in the predictive diagnosis scheme is determined.

Clinical Laboratory Techniques↗