Pressure and volume relationships in the ventricle, conus and arterial arches of the frog heart.
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Animals↗
Biomedical subjects
D R Jones
Publications and source records attributed to D R Jones.
The design of a sequential clinical trial for the comparison of two lung cancer treatments.
The steps in designing a controlled trial to evaluate a new treatment for inoperable carcinoma of the bronchus are described. The principal outcome measure is survival time from treatment allocation, and the duration of the trial is determined by application of the sequential logrank test. The detailed determination of the stopping rule and the arrangements for analyses are described.
Carcinoma, Bronchogenic↗
The analysis of a sequential clinical trial for the comparison of two lung cancer treatments.
Methods adopted in the analysis of data from a randomized controlled trial of a new treatment for inoperable lung cancer are described. The trial design employed the sequential logrank test using length of survival from time of randomization as the principal outcome measure. We describe the practical arrangements for regular inspections of the accumulating data as required by the sequential design, and also for more extensive but less formal interim analyses, and present some of the results. On termination of the trial the survival patterns of the two treatment groups were compared using methods of analysis developed specifically to allow for the sequential nature of the trial design. The role of prognostic factors was investigated using fixed sample methods which are approximately independent of the sequential design.
Clinical Trials as Topic↗
Measuring and analysing quality of life in cancer clinical trials: a review.
After brief consideration of the definition of the term 'quality of life', methods previously adopted and problems encountered in assessing and evaluating quality of life in clinical studies of cancer are reviewed. Desirable properties of any such assessment methods and approaches to the analysis of quality of life data are discussed. Illustrations are provided by reference to the methods of assessment of quality of life incorporated in two recently-initiated studies of cancer treatment.
Adult↗
Testing for behavioral contagion in a case-control design.
'Behavioral contagion' refers to an increased tendency for a behavior to be performed when socially related persons have already performed it. So understood, behavioral contagion may be involved in criminality, conduct disorder, drug abuse, suicide, and teenage pregnancy. In a recent paper we showed that contagion, when present, generates highly distinctive result patterns in survey data. These patterns allow one to infer that contagion is present even though it has not been directly observed. The present paper extends this approach to case-control designs, where, it will be shown, contagion has equally distinctive but different consequences. The analysis is illustrated with a Canadian study of conduct disorder and further evidence is presented that this condition is contagious. Limitations of the approach and alternative interpretations of results are discussed.
Adolescent↗
Preferred pathways of behavioral contagion.
A behavioral disorder is "contagious" if the risk to a given individual increases when someone in that person's vicinity, family, or social group develops the disorder. So understood, behavioral contagion may be involved in criminality, conduct disorder, drug abuse, suicide, and teenage pregnancy. Previous papers have shown that contagion generates highly distinctive result patterns, from which its presence may be inferred. The patterns concern prevalence in sibships of different size and, in case-control designs, the number of susceptible sibs that affected and unaffected individuals have. The present paper extends the analysis by allowing the likelihood of transmission from one sib to another to vary according as the two sibs are of the same or opposite gender, male or female, single borns or co-twins, fraternal or identical twins. The extension is illustrated by application to data on criminality in Danish twins previously reported by other workers. We will show that the distribution of criminality by gender and zygosity is better explained in terms of behavioral contagion than by previous analyses.
Adolescent↗
Once a scientist, always a scientist. A double anniversary for A. Michael Michelson in 2006: 80th birthday and 60 years in research.
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Biochemistry↗
The autonomic nervous control of heart rate in ducks during voluntary diving.
Autonomic nervous control of heart rate was studied in voluntarily diving ducks (Aythya affinis). Ducks were injected with the muscarinic blocker atropine, the beta-adrenergic blocker nadolol, the beta-adrenergic agonist isoproterenol, and a combination of both atropine and nadolol. Saline injection was used as a control treatment. The reduction in heart rate (from the predive level) normally seen during a dive was abolished by atropine. Nadolol reduced heart rate during all phases of diving activity-predive, dive, and postdive-indicating that sympathetic output to the heart was not withdrawn during diving. Isoproterenol increased heart rate before, during, and after the dive, although the proportional increase in heart rate was not as high during the dive as compared with the increase in routine heart rate or heart rate during the predive or postdive phase. The parasympathetic system predominates in the control of heart rate during diving despite the maintenance of efferent sympathetic influences to the heart, perhaps due to accentuated antagonism between the two branches of the autonomic nervous system.
Animals↗
Meta-analysis and the synthesis of evidence.
Use of meta-analytical (quantitative overview) techniques is now commonplace in a large range of medical-research contexts, with a rapid rise in its frequency of use being particularly apparent in the last decade. Many methods of meta-analysis have been proposed and used, from crude 'vote-counting' of studies showing significant or nonsignificant results, through methods for combination of effect-size estimates based on fixed- or random-effects models, to general, linear, mixed models and Bayesian methods. The history of meta-analysis and the advantages and disadvantages of various approaches to it are briefly reviewed in this paper, with reference to its application in health-services research and related fields. Broader approaches to the synthesis of evidence in these contexts using conventional multilevel modelling and hierarchical Bayesian models to address the combination of evidence from disparate types of study are then outlined.
Bayes Theorem↗
Gestational age and cell viability determine the effect of frozen storage on human fetal hematopoietic progenitor cell preparations.
We have assessed hematopoietic progenitor cell preparations (including CD34-positive stem cells) obtained from human fetal liver at 6-17 weeks of gestational age for total cell numbers, viability and the ability to tolerate (frozen) storage. Hematopoietic cell preparations obtained from the 16-to 17-week gestational age range had the highest total cell count and the greatest proportion of CD34-positive stem cells. However, these preparations were insufficiently robust to withstand the freeze/thaw protocol required. Cells obtained from the 13- to 15-week gestational age range showed optimal post-thaw viability and it is suggested that these cell preparations are the most applicable for in utero transplantation.
Abortifacient Agents, Steroidal↗
A Bayesian approach to a general regression model for ROC curves.
A fully Bayesian approach to a general nonlinear ordinal regression model for ROC-curve analysis is presented. Samples from the marginal posterior distributions of the model parameters are obtained by a Markov-chain Monte Carlo (MCMC) technique--Gibbs sampling. These samples facilitate the calculation of point estimates and credible regions as well as inferences for the associated areas under the ROC curves. The analysis of an example using freely available software shows that the use of noninformative vague prior distributions for all model parameters yields posterior summary statistics very similar to the conventional maximum-likelihood estimates. Clinically important advantages of this Bayesian approach are: the possible inclusion of prior knowledge and beliefs into the ROC analysis (via the prior distributions), the possible calculation of the posterior predictive distribution of a future patient outcome, and the potential to address questions such as: "What is the probability that a certain diagnostic test is better in one setting than in another?"
Bayes Theorem↗
Corer-reactors for contaminant flux measurement in sediments.
Design details and operating instructions are provided for a sediment corer that can be converted into a reactor for the measurement of the fluxes of contaminants from sediments to overlying waters. The corer-reactor permits measurements, under controlled laboratory conditions, on intact, largely undisturbed sediment cores, without significantly perturbing the physical and chemical conditions found in the field. The design can be constructed in-house for around US dollar 240 (A dollar 400) (excluding motor and corer lid), making it a relatively inexpensive system.
Environmental Monitoring↗
Implanted right atrial catheters for continuous infusion of solutions into dogs.
Silastic catheters were fabricated and aseptically implanted through the skin into the jugular vein of 64 dogs with the intravascular tip located in the right atrium. Solutions were infused through the catheter at 2 to 2.5 mL/h by a portable pump worn by the dog. Following 9.2 Gy total body irradiation (TBI) and allogeneic bone marrow transplantation (BMT), succinyl acetone, an experimental chemotherapeutic agent, was infused into 34 dogs. Hematopoietic growth factors were infused into an additional 30 dogs, two of which had 9.2 Gy TBI and an autologous BMT, and four of which had 4.0 Gy TBI and no BMT. All dogs received continuous oral and parenteral antibiotics while the catheters were in place. All catheters functioned well until electively removed (n = 28) or until the dogs died or were euthanized (n = 36) at 12 to 68 days after implantation. Mean length of catheter function was 30.3 +/- 1.5 (SEM) days. No catheters were dislodged and there was no evidence of catheter-related blood loss or sepsis. Semiquantitative cultures of 5 catheters were negative, but Staphylococcus epidermidis was isolated from 3 of 7 catheters cultured in broth. Six dogs had thrombosis adjacent to the intravascular catheter tip. The catheters were well tolerated and facilitated successful long-term infusion of solutions into dogs.
Animals↗
Demographic and predictive correlates of smokeless tobacco use in elementary school children.
BACKGROUND: To assess the basic demographics and predictive correlates of smokeless tobacco use in school-age children, a stratified random sample of 559 rural and urban first, third, fifth, and seventh graders in western North Carolina was surveyed regarding experimentation with smokeless tobacco. METHODS: Two versions of a survey were developed: a shorter version administered orally to first graders and a longer version provided to others. Reported percentages across demographic variables were broken down in a 4 x 2 x 2 analysis of variance; correlations were used to assess the relationships among potentially predictive variables. RESULTS: Results indicated that 36 percent of male rural first graders had tried smokeless tobacco, increasing to 70 percent by the seventh grade. Overall, rural males were more likely to have tried or be regularly using smokeless tobacco than were urban males or females. Other questions correlating with smokeless tobacco use indicated that it is predicted by three general concerns: a) perceived flavor, b) self-concept and presentation to peers, and c) family influence. DISCUSSION: Educational interventions must begin at the kindergarten or first grade levels. Programs for adolescents must provide for alternative ways of receiving perceived social image benefits of smokeless tobacco use. Familial support must be considered in all programming.
Analysis of Variance↗
A microprocessor-based digital echocardiography system.
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Computers↗
A system for quantitative evaluation of left ventricular function with two-dimensional ultrasonography.
Phased-array ultrasonic imaging systems produce real-time sectional images of the left ventricle. To quantify left ventricular function, a light-pen-based system was developed using a minicomputer to analyze the geometry of ultrasound images and measure left ventricular volume, ejection fraction, and regional contraction. System accuracy was evaluated by comparing measurements abtained from left ventricular cineangiograms at cardiac catheterization on a series of 25 patients to echocardiographic left ventricular long- and short-axis linear dimensions (r = 0.92, S.E.E. = 0.67 cm), end-diastolic volume (r = 0.84, S.E.E. = 45 cm3), and ejection fraction (r = 0.80, S.E.E. = 0.10). Five patients from the study population with electrocardiographically documented transmural myocardial infarcts had regional contraction abnormalities detected by this analytic approach. Quantitative application of two-dimensional echocardiography appears to be a useful noninvasive method of evaluating left ventricular ejection fraction and has potential to define regional contraction abnormalities objectively.
Cardiac Output↗
Affective and physiological responses to racism: the roles of afrocentrism and mode of presentation.
Recent experiments have examined the subjective and physiological responses of African Americans to racism using video-taped vignettes or emotional imagery. These studies reported changes in mood and increases in cardiovascular (CV) and electromyographic (EMG) activity when analogs of the stressful situations were encountered. In addition, individual differences in responses were found to be related to various personality measures. The present study examined the mood, CV and EMG responses of 60 African-American women as they encountered social situations that included blatant and more subtle forms of racism. Half of the sample viewed both vignettes while the remainder imagined them. The relationship between responses and Afrocentrism, a measure related to black identity, was examined. Significant changes in heart rate, digital blood flow and facial muscle activity in the corrugator regions resulted. The most pronounced changes occurred when blatantly racist material was encountered. Mood changes tended to be stronger when material was imagined versus viewed. In general, Afrocentricity was not related to physiological responses to the scripts, though mood responses and Afrocentricity were related in several instances. The findings indicate that CV, as well as EMG and mood responses, are sensitive to various forms of racism presented in imagery and video modes.
Adult↗