Allocating student nurses by computer.
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Computers↗
Biomedical subjects
R Saunders
Publications and source records attributed to R Saunders.
A prospective study of the determinants of physical activity in rural fifth-grade children.
BACKGROUND: Understanding the factors that influence physical activity behavior is important in the design of intervention programs targeted at youth. METHODS: A prospective study design was used to identify the predictors of vigorous physical activity (VPA) (> or = 6 METs) and moderate and vigorous physical activity (MVPA) (> or = 3 METs) among 202 rural, predominantly African-American children. Selected social-cognitive determinants of physical activity were assessed via questionnaire in the fifth grade. Participation in VPA and MVPA was assessed via the previous day physical activity recall 1 year later in the sixth grade. RESULTS: For girls, participation in community sports, self-efficacy in overcoming barriers, enjoyment of school physical education, race (white > black), and perception of mother's activity level (active vs inactive) were significant predictors of VPA. For MVPA, participation in community sports and self-efficacy in overcoming barriers were significant predictors. For boys, self-efficacy in overcoming barriers was the only significant predictor of VPA, while beliefs regarding activity outcomes and participation in community sports were significant predictors of MVPA. CONCLUSION: Social-cognitive constructs such as physical activity self-efficacy, access to community physical activity outlets, and positive beliefs regarding physical activity outcomes are important predictors of future physical activity behavior among rural, predominantly African-American children.
Analysis of Variance↗
WHO health risk assessment process for static fields.
The World Health Organization (WHO) has a commitment to helping Member States achieve safe, sustainable and health-enhancing human environments, protected from biological, chemical and physical agents. The latter includes advising on the health impact of electromagnetic fields (EMFs) and radiation. The results of the WHO/ICNIRP/NRPB workshop on static magnetic fields, published in this volume, provide a valuable and much needed contribution to the health risk assessment of exposure to static electric and magnetic fields, which is currently being coordinated by the WHO's International EMF Project. This WHO health risk assessment will be published as an environmental health criteria (EHC) monograph in early 2005. This paper briefly gives an overview of the process of developing the WHO static fields EHC monograph, the criteria applied to studies that could contribute to the EHC, along with the 'weight-of-evidence' approach to health risk assessment. In addition, there is an increasing awareness of the need to account for uncertainty in the science database. This is traditionally addressed by further research, and the EMF project addresses these needs through the development of a 'research agenda'. However, research programmes may take several years to complete, and the long latency associated with diseases such as cancer in people may also preclude a rapid outcome in some studies. The issue of current uncertainty is being addressed by the WHO EMF project through the development of a 'precautionary framework' in which precautionary measures will be applied to policy recommendations.
Dose-Response Relationship, Radiation↗
Effects of hydroxyethyl starch on fibrinogen, fibrin clot formation, and fibrinolysis.
The effects of hydroxyethyl starch on the final stages of hemostasis were investigated in vivo and in vitro. When compared to control solutions of either 5 percent albumin or isotonic (0.9%) NaCl, 6 percent hydroxyethyl starch (HES) exerted several effects. Results of in vivo studies were as follows: following infusion of 1 liter of 6 percent HES into healthy subjects, fibrinogen and antithrombin-III concentrations fell slightly due to plasma volume expansion and consequent dilution. Concentrations of fibrin monomer and fibrin-fibrinogen degradation products remained unchanged. Thrombin and reptilase clotting times were shortened to indicate rapid detection (and presumably accelerated formation) of fibrin clots. Urokinase-activated clot lysis times were shortened to suggest rapid fibrinolysis. Results of in vitro studies were similar. Shortened thrombin, reptilase, and urokinase-activated clot lysis times were reproduced in vitro by mixing HES, but not albumin or NaCl, with normal plasma. Although these findings qualitatively are similar to those reported previously for dextran, the molecular mechanisms involved and the clinical importance, if any, of the hemostatic effects remain to be defined. Thus, it would be premature to conclude either that HES or dextran exert identical biological effects on hemostasis or that the two agents possess similar clinical properties. HES has an excellent safety record when it has been used during leukocytapheresis and for plasma volume expansion in recommended doses. Its effects when given in larger doses remain to be defined.
Antithrombin III↗
Effects of hydroxyethyl starch on blood coagulation, particularly factor VIII.
The effects of hydroxyethyl starch (HES) on hemostasis were investigated extensively. In order to simulate acute blood loss due to surgery or trauma, one unit (450 ml) of blood was drawn from normal healthy men. This was followed by a 1-liter infusion over 60 minutes of either 6 percent HES, 5 percent albumin, or 0.9 percent sodium chloride (NaCl) as replacement. Coagulation studies were performed before phlebotomy, before infusion and at 0, 4, 20, 27, and 92 hours following infusion. Following infusion of HES and albumin, plasma fibrinogen and antithrombin-III levels fell slightly due to plasma volume expansion and hemodilution. In subjects receiving HES, partial thromboplastin times (PTTs) were significantly (p less than .05) prolonged and factor VIII activities were significantly (p less than .05) decreased when compared to the albumin and NaCl groups. These findings could not be attributed solely to hemodilution. The effects of HES on PTT and factor VIII could not be correlated with plasma HES levels; neither could they be reproduced in vitro by mixing HES with normal plasma. Mean values of the following studies remained normal after infusion of all replacement fluids: prothrombin time, bleeding time, fibrin monomer, fibrin-fibrinogen degradation products, platelet adhesion, circulating platelet aggregates, and platelet count.(ABSTRACT TRUNCATED AT 250 WORDS)
Adolescent↗
Mechanical strength of single microcapsules determined by a novel micromanipulation technique.
A micromanipulation technique has been developed to measure the bursting force of single dry microcapsules coated onto a surface, such as those normally used in carbonless copying paper. For measuring the bursting force of a given microcapsule, a single fine probe with a flat end about 10 microns in diameter was used to squeeze the microcapsule against a flat surface until it burst. The force being imposed on the microcapsule was measured by a transducer connected to the probe. The bursting force and diameter of single dry microcapsules in two samples, different in size and wall thickness, were measured by this technique. The bursting force of the microcapsules in one sample ranged from 50 to 220 microN and the diameter from 1.3 to 7.0 microns, whilst the bursting force in the other was from 20 to 175 microN and the diameter from 0.7 to 3.7 microns. This technique makes it possible to compare the mechanical strength of microcapsules made of different formulations, and to infer information about microcapsule mechanical properties.
Capsules↗
Thermal stress and radiation protection principles.
Exposure to radiofrequency (RF) fields can occur in residential, occupational and medical settings. Since many technologies use RF fields, it is important to fully investigate their effects on the human body. Since the demonstrated effect of RF exposure is heating, it is important to critically evaluate studies of elevated temperature effects on the human body, from the cellular and tissue level to the whole body level, including potential effects on the susceptible groups such as the very young and the very old. WHO convened a Workshop in the Spring of 2002 on the subject of Adverse Temperature Levels in the Human. The goal of the workshop was to evaluate most recent data useful for the development of science-based RF exposure limits. This paper outlines radiation protection principles that underline such an evaluation. It discusses the quality of literature needed for sound scientific reviews, provides the hierarchy of scientific evidence used to establish effects, distinguish between biological effects and adverse health consequences and indicates how evidence is evaluated. In addition, criteria for determining the most sensitive effects, the value of an effect that has a dose-response and methods of extrapolation are also described. Finally, the need to account for scientific uncertainty in the formulation of guidance on exposure is discussed.
Dose-Response Relationship, Radiation↗
A closer look at chemical dependency. Dealing with co-workers who abuse drugs, drink.
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Alcoholism↗