A new method to monitor drugs at dance venues.
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Dancing↗
Biomedical subjects
J D Ramsey
Publications and source records attributed to J D Ramsey.
Task performance in heat: a review.
A wide array of variable conditions, tasks, subject populations, etc., have been included in studies that have produced data on perceptual motor performance in the heat. This paper uses a methodology for comparing these studies, regardless of the inherent differences, which allows determination of whether thermal effects are dominant enough to persist through diverse combinations of variables. Approximately 160 individual studies of perceptual motor performance reported in the literature were summarized based on thermal level, duration of exposure and the type of task performed. Results indicated no dominant effect of duration of exposure to the heat and no dominant effect of thermal level on mental/cognitive tasks. For perceptual motor tasks other than very simple or mental tasks, an onset of performance decrement was noted in the 30-33 degrees C WBGT range of temperature. This temperature level is consistent with the Recommended Exposure Limits for work in the heat at low levels of metabolic heat.
Arousal↗
Use of ventricular stroke work index and ventricular function curves in assessing myocardial contractility.
Cardiac output and cardiac index values are traditionally used by critical care nurses as indicators of myocardial contractility. Due to the incidence of compensatory tachycardia in many critically ill patients, however, the value of LVSWI as an indicator of myocardial contractility is enhanced, because the formula for its calculation does not emphasize the variable of heart rate. The advantages of using LVSWI are the following: It is easily calculated at the bedside by using an integrated hemodynamic software package or by using the formula provided. It is readily available to the nurse and indicates sensitive changes in myocardial function. When used in LV function curves in the nursing assessment of myocardial contractility of critically ill adults, its use can direct changes in fluid and pharmacologic interventions. Factors that affect ventricular end-diastolic pressure such as altered myocardial compliance or increased transmural pressure alters PCWP. Although LVSWI is not completely independent of these factors and may be less precise with altered PCWP, the LVSWI does enhance the data base used to manage patients with altered ventricular function. Ideal LVSWI values may not be achievable in patients with poor myocardial contractility; however, tracking the LVSWI provides sensitive and immediate feedback on the efficacy of pharmacologic intervention. Critical care nurses should use the LVSWI for any hemodynamically unstable patient whose myocardial contractility might be compromised. This information allows the nurse to optimize the patient's hemodynamic performance with a more accurate assessment of heart function.
Cardiac Output↗
The predictive accuracy of in vitro measurements for the dermal absorption of a lipophilic penetrant (fluazifop-butyl) through rat and human skin.
The predictive accuracy of in vitro measurements in estimating dermal absorption has been evaluated in rat and human skin using fluazifop-butyl (FB), a lipophilic model compound, at dosage rates of 2.5, 25, and 250 micrograms/cm2. In vitro studies used rat and human epidermal membranes mounted in static diffusion cells with radiolabeled FB and receptor fluids of 50% aqueous ethanol (Aq Et), 6% polyethylene glycol 20 oleyl ether in saline (PEG), or tissue culture medium (TCM). In vivo rat studies with radiolabeled FB were carried out to parallel previously published human volunteer studies. For rat skin, in vitro measurements with all types of receptor fluid provide an adequate prediction (generally within a factor of 3) of in vivo absorption. Absorption data for human epidermal membranes with a receptor fluid of Aq Et were adequately predictive of the in vivo absorption. In contrast, membranes with PEG or TCM significantly underestimated the in vivo absorption. The results support the conclusion that in vitro studies are useful to predict in vivo dermal absorption in rat and man, when appropriate receptor fluids are used.
Animals↗
Modelling dermal pharmacokinetics using in vitro data. Part I. Fluazifop-butyl in the rat.
The pharmacokinetics of the herbicide fluazifop-butyl have been determined in female rats following oral and intravenous dosing, and described by a mathematical model. Penetration of fluazifop-butyl through epidermal membranes has been determined using three different receptor fluids. It is demonstrated how this in vitro absorption data can be used with a pharmacokinetic model derived from oral and i.v. dosing studies to predict plasma concentrations and urinary excretion profiles following dermal dosing. Model predictions are compared with experimental measurements and found to be in good agreement.
Administration, Oral↗
Modelling dermal pharmacokinetics using in vitro data. Part II. Fluazifop-butyl in man.
In a previous paper it was demonstrated that dermal absorption of the herbicide fluazifop-butyl in the rat could be modelled by combining a knowledge of the pharmacokinetics following intravenous and oral dosing with in vitro measurements of dermal absorption. This paper demonstrates the validation of a similar model for the dermal absorption of fluazifop-butyl in man. Pharmacokinetic parameters derived from an oral dosing study are combined in a mathematical model with in vitro measurements of dermal absorption of fluazifop-butyl. Model predictions of the rate and extent of dermal absorption of fluazifop-butyl are compared with the results of dermal absorption studies in human volunteers. Good agreement is found between the model predictions and the experimental measurements. These results have implications for improved risk assessment. The model provides a tool for risk assessment based on both internal dose (e.g. peak plasma concentration, plasma area under the curve) as well as total absorbed dose. However, further work is required to evaluate whether the same techniques are applicable to a wider range of compounds.
Administration, Cutaneous↗
Controlling deaths from volatile substance abuse in under 18s: the effects of legislation.
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Adolescent↗
Further validation of an in vitro method to reduce the need for in vivo studies for measuring the absorption of chemicals through rat skin.
Current requirements for the registration of agrochemicals, particularly in the U.S.A., often require the provision of dermal absorption data. In this process the rat is often used and complex in vivo studies, using large numbers of animals, are performed. We have compared the data obtained from in vivo and in vitro dermal absorption studies using eight pesticides with a range of physicochemical properties. Measurements were made of the 14C-labeled pesticides which could be washed from the skin, were associated with (on/in) skin, or absorbed through the skin following dermal applications in vivo and in vitro at various time points over a 24-hr exposure period. Good agreement was found between the amounts washed from and associated with the skin in vivo and in vitro. Over the time period 4-24 hr after application the in vitro experiments predicted the in vivo absorption within a factor of 2-3. These results show that, with a range of pesticide molecules, the in vitro method accurately predicted in vivo absorption supporting the utilization of the in vitro method for risk assessment from exposure to pesticides and other chemicals.
Animals↗
Detection and identification of volatile substances by headspace capillary gas chromatography to aid the diagnosis of acute poisoning.
Headspace gas chromatography with split flame-ionization-electron-capture detection is a simple method of screening for a wide range of volatile substances in biological fluids. A 60 m x 0.53 mm i.d. thick-film (5 microns) fused-silica capillary coated with SPB-1 (Supelchem) with split flame-ionization-electron-capture detection provides a valuable alternative to packed columns in this work. Most commonly abused compounds, including many with very low boiling-points such as bromochlorodifluoromethane (BCF), butane, dimethyl ether, FC 11, FC 12, isobutane and propane, can be retained and differentiated at an initial column temperature of 40 degrees C followed by programming to 200 degrees C. The total analysis time is 26 min. Retention and detector response data were generated for 244 compounds. Good peak shapes are obtained for polar analytes such as ethanol and injections of up to 0.30 cm3 of headspace can be performed with no discernable loss of efficiency. The sensitivity is thus at least as good as that attainable with packed columns. Of the commonly encountered compounds, only isobutane-methanol and paraldehyde-toluene are at all difficult to differentiate. Quantitative measurements can be performed either isothermally or by using the temperature programme.
Acute Disease↗
Pharmacokinetics of fluazifop-butyl in human volunteers. II: Dermal dosing.
1. The absorption of the herbicide fluazifop-butyl (f-b), has been determined from plasma and urine measurements in groups of six male volunteers following dermal administration of 2.5, 25 and 250 micrograms cm-2 from standardized formulations containing 0.05, 0.5 and 5.0% (w/v) fluazifop-butyl to a skin area of 800 cm2. 2. Urinary excretion rate of the principal metabolite fluazifop, following dosing with the 5% formulation, was described by a two-compartment pharmacokinetic model; the average elimination half-lives of initial and terminal phases were 18 h and approximately 70 h, respectively. For the other dose levels the elimination half-life was estimated to be 17 h; urine concentrations at later time points were too low to characterize a second compartment. 3. The estimated total fluazifop-butyl absorbed was 8.0, 3.4 and 1.6% of the applied dose for the 0.05, 0.5 and 5.0% formulations, respectively. 4. Up to 50% of the applied fluazifop-butyl was readily removed by skin washing and the majority of the remainder was transferred to clothing during the 24 h following application. 5. When six volunteers were given a daily dermal dose of the 0.5% formulation for five consecutive days, the plasma and urinary excretion kinetics of fluazifop could be accurately predicted by simple mathematical extrapolation of the kinetic data from the single exposure study at the equivalent daily dose. 6. It is concluded that fluazifop-butyl is only slowly and poorly absorbed through human skin and has a low potential to accumulate in man.
Administration, Cutaneous↗
The response of evidential breath alcohol testing instruments with subjects exposed to organic solvents and gases. I. Toluene, 1,1,1-trichloroethane and butane.
Experimental work has been undertaken to investigate the potential interference of toluene, 1,1,1-trichloroethane and butane with the evidential breath alcohol testing instruments used in Great Britain (Lion Intoximeter 3000 and Camic Breath Analyser). Volunteers inhaled the volatile substances in an exposure chamber for up to 4 hours, at concentrations of 100, 350 and 600ppm respectively. Subsequently breath was tested on leaving the chamber. No interference was observed with the breath alcohol instruments when the subjects were exposed to toluene and 1,1,1-trichloroethane. A short-term response immediately after exposure was observed for subjects exposed to butane. Further analytical work involving blood and breath samples demonstrated that all three volatile substances were absorbed during exposure and were detectable in blood for at least 3 hours post-exposure. Their elimination post-exposure followed an exponential decay.
Adult↗
The response of evidential breath alcohol testing instruments with subjects exposed to organic solvents and gases. II. White spirit and nonane.
Following exposure to white spirit vapour, the effect of the expired solvent on evidential breath alcohol equipment was investigated under controlled exposure chamber conditions and in a simulated painting exercise. Five volunteers inhaled the solvent in an exposure chamber at a concentration of 100ppm for periods up to 4h 17min. Two other volunteers were exposed to white spirit while painting with domestic gloss paint in an unventilated room under which conditions exposure concentrations reached 185ppm for 20min. Following all white spirit exposures, volunteers underwent breath tests with the Lion Intoximeter 3000. In all instances the apparent alcohol responses were very small and never exceeded a reading of 1 microgram/100ml for breath samples more than 10min post-exposure. Simultaneous analytical work was conducted to demonstrate that white spirit was absorbed during exposure and was present in the breath and blood after the volunteers had left the exposure atmospheres. A further study involved the exposure of a volunteer to nonane vapour at 100ppm, demonstrating that this compound, being one of the principal components of white spirit, appears to be a good model for studying the uptake and elimination of white spirit.
Adult↗
The response of evidential breath alcohol testing instruments with subjects exposed to organic solvents and gases. III. White spirit exposure during domestic painting.
The concentration of white spirit vapour in the breathing zone of a volunteer engaged in domestic painting activities has been investigated. Air was continuously sampled and analysed using an infra-red gas analyser (Miran) during painting experiments. Both indoor and outdoor painting tasks were undertaken using commercial paints in a wide variety of situations. For each task the time weighted average (TWA) exposure has been determined. In no case did the TWA exposure exceed the Occupational Exposure Limit-Long Term Exposure Limit (OEL-LTEL) of 100 ppm. The results have been used to discuss the significance of previous studies in which volunteers were exposed to white spirit vapour in an exposure chamber to test for possible interference in breath alcohol testing.
Breath Tests↗
Volatile substance abuse--an overview.
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Adolescent↗
Analytical toxicology.
1. Major advances in analytical toxicology followed the introduction of spectroscopic and chromatographic techniques in the 1940s and early 1950s and thin layer chromatography remains important together with some spectrophotometric and other tests. However, gas- and high performance-liquid chromatography together with a variety of immunoassay techniques are now widely used. 2. The scope and complexity of forensic and clinical toxicology continues to increase, although the compounds for which emergency analyses are needed to guide therapy are few. Exclusion of the presence of hypnotic drugs can be important in suspected 'brain death' cases. 3. Screening for drugs of abuse has assumed greater importance not only for the management of the habituated patient, but also in 'pre-employment' and 'employment' screening. The detection of illicit drug administration in sport is also an area of increasing importance. 4. In industrial toxicology, the range of compounds for which blood or urine measurements (so called 'biological monitoring') can indicate the degree of exposure is increasing. The monitoring of environmental contaminants (lead, chlorinated pesticides) in biological samples has also proved valuable. 5. In the near future a consensus as to the units of measurement to be used is urgently required and more emphasis will be placed on interpretation, especially as regards possible behavioural effects of drugs or other poisons. Despite many advances in analytical techniques there remains a need for reliable, simple tests to detect poisons for use in smaller hospital and other laboratories.
Doping in Sports↗
The prediction of temperatures and heat stress limits in the workplace with natural ventilation.
This paper presents a simple procedure for using the climatic factors reported by weather bureaus to predict levels of heat stress and conditions of risk in the workplace. For an aluminum reduction plant with natural ventilation, the study showed that the air temperature inside followed the same pattern of annual changes as the normal maximum ambient temperature outside the building. The Wet Bulb Globe Temperature (WBGT) was correlated significantly with air temperature (ta). With limited measurements, WBGT was predicted for the entire year at different locations in the shop.
Hot Temperature↗
Comparison of the in vivo and in vitro percutaneous absorption of a lipophilic molecule (cypermethrin, a pyrethroid insecticide).
The absorption of a pyrethroid insecticide, cypermethrin, through rat skin has been measured both in vitro and in vivo. Cypermethrin did not penetrate in vitro through whole skin but did penetrate epidermal membranes. The in vitro absorption was influenced by the choice of receptor fluid in the glass diffusion cell. There was good agreement between in vivo and in vitro data using 50% aqueous ethanol, 6% Volpo 20, or total calf serum receptor fluids. Rat epidermal membranes in vitro were more than 20 times more permeable to cypermethrin than human epidermal membranes, indicating that cypermethrin would be less readily absorbed in humans than in the rat. The percutaneous absorption in vitro technique using epidermal membranes was successfully used with this lipophilic chemical to predict the in vivo absorption in the rat.
Animals↗
In vitro absorption of some o-phthalate diesters through human and rat skin.
The absorption of undiluted phthalate diesters [dimethyl phthalate (DMP), diethylphthalate (DEP), dibutyl phthalate (DBP) and di-(2-ethylhexyl)phthalate (DEHP)] has been measured in vitro through human and rat epidermal membranes. Epidermal membranes were set up in glass diffusion cells and their permeability to tritiated water measured to establish the integrity of the skin before the phthalate esters were applied to the epidermal surface. Absorption rates for each phthalate ester were determined and a second tritiated water permeability assessment made to quantify any irreversible alterations in barrier function due to contact with the esters. Rat skin was consistently more permeable to phthalate esters than the human skin. As the esters became more lipophilic and less hydrophilic, the rate of absorption was reduced. Contact with the esters caused little change in the barrier properties of human skin, but caused marked increases in the permeability to water of rat skin. Although differences were noted between species, the absolute rates of absorption measured indicate that the phthalate esters are slowly absorbed through both human and rat skin.
Absorption↗