Biomedical subjects

J F Stevenson

Publications and source records attributed to J F Stevenson.

7 recordsLinked to original sources

PubMed2001

Social influence processes and college student drinking: the mediational role of alcohol outcome expectancies.

OBJECTIVE: Social influences are among the most robust predictors of adolescent substance use and misuse. Studies with early adolescent samples have supported the need to distinguish among various types of social influences to better delineate relations between social factors and alcohol use and problems. METHOD: The first major goal of the present study (N = 399, 263 women) was to examine unique relations between particular facets of social influence and alcohol use and problems in a relatively heavy-drinking population (i.e., college students). We hypothesized that active social influences (offers to drink alcohol) and passive social influences (social modeling and perceived norms) would demonstrate positive associations with measures of alcohol use and problems. We also tested the hypothesis that alcohol outcome expectancies would mediate associations between social influences and drinking behaviors. RESULTS: Structural equation modeling analyses provided strong support for the first hypothesis. Social modeling demonstrated the strongest association with alcohol use and problems, and active social influences demonstrated significant associations with both use and problems. Perceived norms were related to alcohol use, but not directly with alcohol problems. Support for the second hypothesis was positive but limited to one type of social influence. Strong evidence for a mediational role of outcome expectancies was found for relations between social modeling and alcohol use and problems. CONCLUSIONS: Together, these findings demonstrate the unique and relative contribution of active and passive social influences and provide limited support for a hypothesized process by which social factors influence cognitions and alcohol-related behaviors.

Adolescent↗

PubMed1999

Decisional balance for immoderate drinking in college students.

Immoderate drinking in college is common and is associated with significant negative sequelae. In this study, measures of Decisional Balance for Immoderate Drinking were developed. This construct is proposed to represent the basic decision-making process that is used by students when deciding whether to drink at immoderate levels or not. Furthermore this construct is embedded in a larger model of behavior change, the Transtheoretical Model of Change, which has been shown to be effective in understanding many health-related behaviors across a wide variety of populations. A total of 629 college students were administered a 25-item decisional balance questionnaire in 1993-1994. Exploratory and confirmatory analyses suggested two different solutions, a two-factor solution and a three-factor solution, but did not provide clear evidence for the psychometric superiority of one over the other. The three-factor solution was chosen as it was seen as an elaboration of the two-factor solution, and validity evidence for this solution is presented. The three factors were labeled the Pros, the Cons-Actual, and the Cons-Potential of Immoderate Drinking. The Cons-Actual scale is a measure of negative affective states associated with current drinking whereas the Cons Potential measures the risk of more concrete negative effects of drinking. External validity was established by the significant and meaningful differences on a number of alcohol-related variables including consumption variables, three measures of negative sequelae of immoderate drinking, and Stage of Change, the organizing construct of the Transtheoretical Model of Change.

Adolescent↗

PubMed1989

Minimal neuropsychological sequelae following prophylactic treatment of the central nervous system in adult leukaemia and lymphoma.

The potential long-term toxicity of central nervous system prophylaxis (CNS-P) in adult acute lymphoblastic leukaemia (ALL, n = 17) and non-Hodgkin's lymphoma (NHL, n = 7) was investigated in a multidisciplinary study. At least 4 years had elapsed from CNS-P (mean 11.5 years) for all patients. Neurological history and physical examination were unremarkable; minor signs were commoner in older patients (P less than 0.02). Psychometry yielded normal results, but individual verbal IQ generally exceeded performance IQ, with a trend to more marked differences in younger adults (P = 0.06). EEG was scored and differed significantly from that of controls, with a tendency to more marked (but still minor) abnormalities in younger patients (P = 0.06). Brainstem auditory evoked potentials demonstrated significant but generally minor abnormality in 24% of patients. CT brain scan revealed widening of cerebral hemisphere sulci to greater than 3 mm in 38% of patients; cerebral atrophy was commoner in the older group (P less than 0.02) and those with neurological signs (P less than 0.02). MRI brain scans were normal in all patients tested. Thus, following standard CNS-P for ALL at this hospital, there is a 5% primary CNS relapse rate, and only minimal, mainly subclinical, long-term neuropsychological toxicity.

Adult↗

PubMed1988

An outcome monitoring system for psychiatric inpatient care.

As the national impetus for examining treatment outcomes increases, the demand for cost-effective systems for psychiatric outcome monitoring grows. This article describes one local effort to develop a monitoring system at Butler Hospital in Providence, Rhode Island. The system uses a combination of face-to-face and computer interviews of a random sample of recently admitted inpatients, with follow-up interviews one month postdischarge and one year following admission. The patient self-report data and interviewer assessment data generated by these interviews are used to quantify patient symptoms and social functioning. With a large enough sample, these findings can be used to identify areas where patient care may be improved. The article also discusses the process and problems involved in implementing the monitoring system and presents illustrative preliminary findings.

Hospital Bed Capacity, 100 to 299↗

PubMed1983

The psychosocial functioning inventory.

The derivation and psychometric analyses of a general purpose outcome/survey instrument--the Psychosocial Functioning Inventory (PFI)--are described. The instrument contains scales designed to measure a wide array of constructs, including subjective well-being, social functioning, stressful events, treatment dependency/aftercare, and consumer satisfaction. Extensive reliability and validity analyses are reported, indicating reasonable reliability and validity for the PFI scales.

Evaluation Studies as Topic↗

PubMed1978

Hydraulic permeability of hollow-fiber membranes.

Two experimental methods have been developed to characterize the pressure-driven flow of a liquid through the walls of single hollow-fiber membranes. In one method, the permeation rate is measured directly by following the air-water interface in a pressurized pipet connected to a hollow fiber which is sealed at one end. With the second method, the permeation rate is determined by tracking the decent of an air bubble inside a pressurized hollow fiber sealed at one end. Results obtained by the two experimental methods are in good agreement. Darcy's law is used to analyze the experimental data because the Darcy permeability constant, k is an intrinsic property of the material. The membrane dimensions and the Darcy permeability constant for reconstituted collagen hollow fibers are shown to be quite sensitive to hydrogen ion concentration and ionic strength. A conceptual link between the Darcy permeability constant and the membrane microstructure is obtained by combining the the aligned-rod structural model for reconstituted collagen proposed by Kramer with a hydrodynamic calculation due to Happel and electrical double-layer theory. On the average, the predictions of this model for volume fraction solids and microstructure dimensions are in reasonable agreement with experimental observations.

Collagen↗

PubMed1975

Extracorporeal model for study of factors affecting thrombus formation.

Factors determining thrombus formation on a foreign surface were studied with the use of plastic flow chambers introduced into extracorporeal shunts. Silicone rubber shunts, joining the carotid artery and jugular vein, were implanted in dogs and remained patent for several weeks. The flow chamber geometry consisted of a 4.8 mm diameter straight tube having a 3.2 X 3.2 mm circumferential cavity in the wall. Chambers were introduced sequentially into the shunts for exposure times of 10 to 30 minutes and regulated blood flow rates of 100 to 400 ml/min. The dry weight of thrombus accumulated in the chamber (5 to 50 mg) was found to increase with exposure time up to 20 minutes and to decrease with increasing flow rate. Various components of the process of thrombus formation were altered by the administration of acetylsalicylic acid, heparin and lysozyme, used alone and in pairs. Heparin was found to be the most effective antithrombotic agent, dry weights of accumulated thrombus being on the order of 50 percent lower when compared to control values. The efficacy of heparin was found to be unaffected by the presence of aspirin and lysozyme, which themselves were not effective antithrombotic agents under the conditions of these experiments. The technique described here may provide a useful animal model for studying the influence of blood flow and different biomaterials on thrombus formation.

Animals↗