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D Priest

Publications and source records attributed to D Priest.

7 recordsLinked to original sources
PubMed1998

Comparative study of the elevation topography of complex shapes.

PURPOSE: To compare the accuracy and precision of the elevation topography from two commercially available instruments using videokeratoscopy or rasterstereography. SETTING: University of Ottawa Eye Institute, Ottawa General Hospital, Ontario, Canada. METHODS: Repeated measurements of elevation topography of six calibrated surfaces were done with the PAR Corneal Topography System (CTS) and the Tomey Topographic Modeling System (TMS-1). The shapes simulated normal (A: aspheric, B: spherocylindric) and postsurgical corneas (C: hyperopic, D: myopic, E: central island, F: phototherapeutic keratectomy). Surface shapes were described by parametric equations. Equation parameters associated with each elevation measurement were determined by best-fit analysis. Measurement precision was assessed by the standard deviation of the difference between the fitted and the measured data. Fitted parameters were compared with nominal values obtained from an independent calibration of each surface. The root mean square error (RMSE) of the deviation of the fitted from the nominal surfaces was used to evaluate the accuracy of each instrument. RESULTS: The accuracy of the CTS exceeded that of the TMS-1 for all surfaces measured. The RMSE values (micron) were (A: 0.1, 6.5), (B: 0.3, 3.8), (C: 1.1, 11.8), (D: 5.0, 43.0), (E: 1.2, 3.2) and (F: 2.2, 17.5) for the CTS and TMS-1, respectively. The differences in the measured data from the fit surface were generally smaller with the TMS-1. CONCLUSION: Quantitative analysis of elevation measurements showed that the CTS represented surface topography more accurately than the TMS-1.

Cornea↗
PubMed1996

Reactive arthritis: characteristics in southern New Zealand.

AIM: To review the clinical characteristics of patients with reactive arthritis and their associated triggering infections in a New Zealand community. METHOD: We reviewed the records of 60 patients with reactive arthritis. For comparison data was also collected on 30 randomly selected patients with psoriatic arthritis. RESULTS: Reactive arthritis affected a young age group. Half the episodes occurred in the age range 16-24 years and the mean age, (SD) of affected patients was 27(10) years cf psoriatic arthritis 40 (17) years, p<0.001. Almost half had a disease course longer than 2 yr and erosive joint damage in one quarter. Two thirds required treatment with sulphasalazine or methotrexate and patients with reactive arthritis were admitted to hospital frequently: 37% vs psoriatic arthritis 7%, p<0.001. Antecedent diarrhoea was documented in 23 episodes whereas a diagnosis of sexually acquired reactive arthritis was made in 11. CONCLUSION: Reactive arthritis has a significant impact on a young age group in this community. This provides a further reason for action to contain the rapidly increasing prevalence in the community of gastrointestinal infections known to trigger reactive arthritis.

Adolescent↗
PubMed1989

The enhancement of the activity of 10-propargyl-5,8-dideazafolate and 5,10-dideazatetrahydrofolate by inhibitors of dihydrofolate reductase.

Treatment of H35 hepatoma cells with the lipid soluble dihydrofolate reductase inhibitors metoprine and trimetrexate cause a nearly 10-fold increase in the toxicity of the antipyrimidine folate analogue PDDF and the antipurine folate analogue DDATHF. Evaluation of these interactions by the combination index developed by Chou (17-20) yields results conforming to synergistic interactions. The capacity of PDDF to inhibit thymidylate synthase in intact cells as measured by tritium release from [5-3H]deoxyuridine was increased by approximately the same amount by preincubation with the dihydrofolate reductase inhibitors. The primary effect of the reductase inhibitors in causing greater activity may be a reduction in cellular folates which can cause 5,10-CH2H4PteGlun to decrease and cellular PDDF (polyglutamates) to increase. These conditions would favor inhibition of thymidylate synthase by PDDF by promoting formation of the stable, inhibited PDDF (polyglutamates)-thymidylate synthase-dUMP complex (12).

Animals↗
PubMed1987

The role of folylpolyglutamate synthetase and gamma-glutamyl hydrolase in altering cellular folyl- and antifolylpolyglutamates.

The metabolic products of methotrexate differ in hepatocytes and hepatoma cells; the primary products are 7-hydroxymethotrexate in hepatocytes and the polyglutamate derivatives in hepatoma cells. The rate of glutamylation is approximately 5-fold greater in hepatoma cells than hepatocytes under comparable conditions and the polyglutamate products in the hepatoma cells consist of longer chain length tri- and tetraglutamate derivatives, whereas the hepatocytes favor the diglutamate derivative. Extracts of cultured hepatocytes have approximately half the folylpolyglutamate synthetase and three times as much gamma-glutamyl hydrolase as the hepatoma cells. A further difference is that methionine inhibits glutamylation in hepatocytes whereas it can cause a marked stimulation (five- to seven-fold) in hepatoma cells. The rate of glutamylation of methotrexate in intact hepatoma cells is strongly dependent on the culture conditions and can be enhanced as much as five-fold in dividing cultures or by removing folates from the cells. These changes may be in part caused by the fact that the folylpolyglutamate synthetase is nearly doubled in both growing cultures and in folate lacking cells. The treatment of human liver in vivo or rodent hepatic cells in vivo and in vitro with methotrexate causes a reduction in the folate pools. Data presented in these studies show that the activity of gamma-glutamyl hydrolase in cells can be enhanced by prior exposure to methotrexate. Thus, methotrexate could cause a loss in cellular folylpolyglutamates by enhancing their rate of cleavage to folylmonoglutamates.

Animals↗
PubMed1985

Pressure sores and paraplegia: an experimental model.

An investigation into the effect of spinal cord transection on pressure sore development is presented and the critical importance of soft tissue atrophy is examined. A technique of spinal laminectomy and spinal cord transection was developed in pigs and shown to have a minimal morbidity rate. Following tissue atrophy, pressure was applied to the paraplegic animals for varying durations. Pressure application was achieved by a computer-controlled application system. The experimental model produced pressure sores extending down to the bone. The resulting tissue damage was assessed, graded, and a pressure-duration curve for paraplegic animals established.

Animals↗
PubMed1983

Differences on Bayley's infant behavior record for a sample of high-risk infants and their controls.

3 groups of high-risk newborns and their controls were assessed at 92 weeks post-conceptional age using Bayley's Infant Behavioral Record (IBR). The 3 groups of high-risk infants were those who weighed 1,500 grams or less at birth and required no ventilator therapy, those weighing 1,500 grams or less at birth who required ventilator therapy, and newborns weighing more than 1,500 grams at birth who required ventilator therapy. Controls were healthy term infants matched for 7 socioeconomic and demographic variables. The first principal component of the IBR ratings for the 3 groups of high-risk infants and the controls were similar. All 3 groups of high-risk infants received less desirable IBR ratings on most items than their controls. In addition, there were some differences among high-risk groups; ventilated infants regardless of birth weight received the lowest ratings reflecting overall performance on the IBR, very low birthweight, ventilated newborns were more likely to receive ratings characterizing an overly active infant with a short attention span, and very low birth-weight, never-ventilated infants were most likely to be rated as happy but passive and delayed. The differences between the high-risk infants and controls in large part resulted from infants who were also delayed in terms of their mental and motor development.

Female↗