Biomedical subjects

D L Pollard

Publications and source records attributed to D L Pollard.

7 recordsLinked to original sources

PubMed2000

Assessment of skin absorption and penetration of JP-8 jet fuel and its components.

Dermal penetration and absorption of jet fuels in general, and JP-8 in particular, is not well understood, even though government and industry, worldwide, use over 4.5 billion gallons of JP-8 per year. Exposures to JP-8 can occur from vapor, liquid, or aerosol. Inhalation and dermal exposure are the most prevalent routes. JP-8 may cause irritation during repeated or prolonged exposures, but it is unknown whether systemic toxicity can occur from dermal penetration of fuels. The purpose of this investigation was to measure the penetration and absorption of JP-8 and its major constituents with rat skin, so that the potential for effects with human exposures can be assessed. We used static diffusion cells to measure both the flux of JP-8 and components across the skin and the kinetics of absorption into the skin. Total flux of the hydrocarbon components was 20.3 micrograms/cm(2)/h. Thirteen individual components of JP-8 penetrated into the receptor solution. The fluxes ranged from a high of 51.5 micrograms/cm(2)/h (an additive, diethylene glycol monomethyl ether) to a low of 0.334 micrograms/cm(2)/h (tridecane). Aromatic components penetrated most rapidly. Six components (all aliphatic) were identified in the skin. Concentrations absorbed into the skin at 3.5 h ranged from 0.055 micrograms per gram skin (tetradecane) to 0.266 micrograms per gram skin (undecane). These results suggest: (1) that JP-8 penetration will not cause systemic toxicity because of low fluxes of all the components; and (2) the absorption of aliphatic components into the skin may be a cause of skin irritation.

Animals↗

PubMed1998

Managing healthcare: a view of tomorrow.

This paper presents a vision of the future in which standards exist at all levels necessary to accomplish true interoperability. The infrastructure has been established to support connectivity among all healthcare-related institutions as well as the population at large. Provider and patient care integrated in the process of an individual's care.

Forecasting↗

PubMed1998

Object technology: raising the standards for healthcare information systems.

Netscape and the public Internet have accelerated the acceptance of many different open "Internet standards". Through wide acceptance of its browser, Netscape gave a boost to the Java programming language helping it become truly platform independent. Objects written in Java are ideal building blocks for application components. CORBA gives such objects the ability to communicate and operate over networks. Applications built with these distributed objects become the services in an Internet-wide healthcare framework. The convergence of object technologies has raised the standards for modern healthcare information systems. To illustrate the relationship among such technologies, this paper presents an architecture for a Universal Healthcare Information System (UHIS) in terms of its web, Java and CORBA components.

Computer Systems↗

PubMed1995

Evaluation of an object-based data model implemented over a proprietary, legacy data model.

Most computerized medical information today is contained in legacy systems. As vendors slowly move to open systems, legacy systems remain in use and contain valuable information. This paper evaluates the use of an object model imposed on an existing database to improve the ease with which data can be accessed. This study demonstrates that data elements can be retrieved without specific programming knowledge of the underlying data structure. It also suggests that underlying data structures can be changed without updating application code. Programs written using the object model were easier to program but ran greater than one order of magnitude slower than traditionally coded programs. In this paper, the legacy information system is introduced, the methods used to implement and evaluate the object-based data model are explained, and the results and conclusions are presented.

Computer Systems↗

PubMed1993

Effect of exposure route on measurement of blood pressure by tail cuff in F-344 rats exposed to OTTO Fuel II.

Male Fischer-344 rats demonstrated a dose-response of blood pressure (BP) to increasing doses of propylene glycol dinitrate (PGDN), the major constituent of OTTO Fuel II (OFII) following administration by subcutaneous injection. Dermal application of the same doses to separate groups of rats resulted in variable responses of BP that were unrelated to dose. A nose-only exposure system was developed but no effect on BP was observed in rats exposed to a nearly saturated atmosphere of PGDN (approx. 750 mg/m3 at 25 degrees C). This study has indicated both the difficulties associated with the use of tail cuff measurement of BP and the need for either a more sensitive or more specific biomarker of effect for exposure to nitrate esters.

Animals↗

PubMed1992

Polychlorotrifluoroethylene (PCTFE) oligomer pharmacokinetics in Fischer 344 rats: development of a physiologically based model.

The hydraulic fluid oil polychlorotrifluoroethylene (PCTFE) is hepato- and nephrotoxic in the rat. Male Fischer 344 rats were exposed to PCTFE either for a single 6-hr exposure (0.5 or 0.25 mg/liter) or daily 5 days/week, 6 hr/day, for 13 weeks (0.5, 0.25, or 0.01 mg/liter). Blood, tissue, and urinary PCTFE concentrations measured postexposure were used to develop a physiologically based pharmacokinetic (PB-PK) model. The PCTFE hydraulic fluid used was a mixture of trimeric and tetrameric oligomers with minor amounts of other chain lengths. The PB-PK model was designed to describe the behavior, not of individual oligomers, but of total mass for the trimer and tetramer in each tissue. Partition coefficients were estimated using the model to optimize tissue/blood concentration ratios measured at the end of the 13-week exposure. First-order metabolic rate constants for both trimeric (2.0 hr-1) and tetrameric (1.0 hr-1) portions were estimated by optimization against urinary fluoride data assuming release of 0.77 mole fluoride per mole trimer and 0.844 mole fluoride per mole tetramer metabolized. To obtain accurate simulation of pharmacokinetic data it was necessary to hypothesize two fat compartments with diffusion-limited exchange of PCTFE oligomer with the blood. Relative concentrations of trimer and tetramer in venous blood, liver, and fat after a single 6-hr exposure were proportional to inhaled concentrations. Tetramer accumulated preferentially with multiple exposure. Components of PCTFE were metabolized to carboxylic acids with release of fluoride. Due to their persistence tetrameric oligomers appear to be more important than trimeric oligomers as causative agents of PCTFE hepato- and nephrotoxicity in the rat.

Administration, Inhalation↗

PubMedDate not supplied

Gas chromatographic determination of propylene glycol dinitrate in rodent skin.

A gas chromatographic (GC) method was developed for the detection of propylene glycol dinitrate (PGDN) in rodent skin following extraction with ethyl acetate. Known quantities of PGDN contained in the torpedo fuel Otto Fuel II were added to homogenates of rat skin, which were subsequently extracted with two 10-mL portions of ethyl acetate. An aliquot of each extract was analyzed by GC with a flame ionization detector. With this method, concentrations ranging from 0.0042 to 11.2 mg/mL were determined by comparison with a standard curve. The extraction efficiencies ranged from 85.7% for the lowest concentration to 101% for the highest concentration.

Animals↗