This study evaluated the effects of disinfection time (10, 30, and 60 minutes) on the surface quality of stone casts poured against an alginate impression material (Jeltrate). Five antimicrobial agents were tested: Sporicidin spray, sodium hypochlorite, and iodophor for spray; and Sporicidin cold sterilization solution and Cidexplus glutaraldehyde solution for immersion. Impressions, flushed with water and stored for 0, 10, 30, and 60 minutes before pouring, served as untreated controls. On completion of the disinfection treatments, the impressions were rinsed and poured in Velmix stone. The effects on cast surface were evaluated under a stereomicroscope by three experienced raters. A 1-to-4 scoring system was developed to rate the surface quality in terms of smoothness and detail reproduction. Both immersion disinfectants proved to be unacceptable for treating alginate impressions. The mean scores of other disinfectant-time combinations were compared with the use of the Tukey-Kramer method with a 95% confidence interval. The results indicated that treatment time had statistically significant effects on the quality of cast surface in Sporicidin spray, sodium hypochlorite, and untreated control groups but not in the iodophor spray group.

Analysis of Variance↗

PubMed1978

Use of the Du Pont aca to measure cholesterol in high-density lipoprotein fractions prepared by the heparin/Mn2+ precipitation method.

The enzymatic cholesterol method used with the Du Pont aca has been modified to provide a reliable measurement of high-density lipoprotein cholesterol in serum after heparin/Mn2+ precipitation of the low- and very-low-density lipoproteins. Interference by Mn2+, equivalent to about 90 mg of cholesterol per liter, is decreased to less than 40 mg of cholesterol per liter by the presence of ethylenediaminetetraacetate (8 mmol/liter) in the diluent; the residual effect of Mn2+ is compensated by calibrating the aca with standards containing Mn2+ and heparin. With an 80-microliter sample, the sensitivity is 236 muA/mg per liter and linearity ranges from 50 to 1500 mg/liter. Average analytical recovery of cholesterol added to the high-density lipoprotein fraction was 103%. Diluted fractions give the expected results. Between-run reproducibility (CV) is 1.3 and 1.6% at 463 and 554 mg/liter. Correlation with the Lipid Research Clinics' procedure (25 samples) gave a regression line of y(aca) = 1.039x- 15, and a correlation coefficient of 0.997.

Chemical Precipitation↗

PubMed1978

125I-radioimmunoassay for unconjugated estriol in serum of pregnant women.

An 125I-radioimmunoassay is described which measures unconjugated estriol in the serum of pregnant women. Estriol is extracted into ethyl acetate/hexane, an aliquot is evaporated, and the residue is redissolved in phosphate buffer. The sample is incubated with tracer and antibody at 37 degrees C for 15 min and then at 4 degrees C for 1 h and 45 min. The antibody-bound fraction is then precipitated with polyethylene glycol and isolated by centrifugation. Because the antigen-antibody complex is stable in the presence of polyethylene glycol, the separation steps are not influenced by timing. Extraction recovery of 3H-labeled estriol added to a pool of sera from pregnant women averaged 96.7% (SD = 1.3, n = 10). Estriol-supplemented (5, 10, and 20 microgram/liter) serum from men, carried through the entire procedure, showed analytical recovery ranging from 94 to 106%. Structurally analogous steroids normally present in serum of pregnant women exhibit negligible cross reactivity. Day-to-day precision (CV) is 13.3% (3.1 microgram/liter), 6.4% (7.6 microgram/liter), and 5.6% (21.4 microgram/liter) for n = 21. The current reagent cost (about 17 cents per tube), and a total procedural time, including counting, of 5.5 h make this an acceptable assay for routine use.

Estriol↗