Evaluation of the Variability of AIZE Rapid Tests on the "imo" Perimeter In Stable Glaucoma Patients.

PRCIS: Analysis of AIZE Rapid test variability in stable glaucoma patients showed that the 95% prediction interval of the MD value, potentially an index for judging progression, was ±1.63 to ±1.78 dB in early-to-moderate-stage patients. PURPOSE: To explore the 95% prediction interval of the mean deviation (MD) value using the AIZE Rapid test strategy for glaucoma observation. METHOD: This study included seventy-two patients with stable or suspected glaucoma who underwent the imo AIZE Rapid test three times or more within two years. Both eyes from each patient were classified as better or worse eyes. They were divided based on baseline MD values into the following four groups: MD > -3 dB, -6 dB < MD ≤ -3 dB, -12 dB < MD ≤ -6 dB, and MD ≤ -12 dB. The variability of MD during the observation period and the 95% prediction intervals were analyzed. Pointwise variability of limits at each test locations were also calculated. RESULTS: The numbers of better and worse eyes included in the study were forty-six and thirty-three. The median follow-up period was 1.3 years (range: 0.5 to 1.9 years). The 95% prediction intervals for MD values were ±1.41 dB for better eyes (n = 46) and ±1.47 dB for worse eyes (n = 33). The 95% prediction intervals in the MD > -3 dB, -6 dB < MD ≤ -3 dB, -12 dB < MD ≤ -6 dB, and MD ≤ -12 dB groups were ±1.63 dB, ±1.34 dB, ±1.78 dB, and ±1.33 dB, respectively. Pointwise variability of worse eyes was larger than better eyes especially in between 10 to 15 dB. CONCLUSION: In the case of a difference in MD greater than the 95% prediction intervals when compared with the previous visual field result, we should pay much attention to the possibility of progression of the glaucomatous visual field in stable glaucoma patients.

Inhibitory effect of lysophosphatidylcholine on pancreatic lipase-mediated hydrolysis in lipid emulsion.

In the lipid metabolism pathway, dietary lipid emulsified with bile salts and phospholipids is mainly digested by pancreatic lipase into free fatty acids and monoacylglycerols. In order to study substrate recognition mechanism of a pancreatic lipase, we investigated its catalytic property toward the lipid emulsion prepared with long- or intermediate-chain acylglycerols and several physiological surfactants. When lysophosphatidylcholine (LysoPC), rather than bile salts or phospholipid, was incorporated into the lipid emulsion, it caused an increase in the Km(app) and a decrease in the Vmax(app) values in the interactions between the lipase and triacylglycerol (triolein or tricaprin). This indicated that LysoPC inhibited hydrolysis by decreasing both the substrate affinities and the catalytic activity of this lipase. Interestingly, further addition of taurodeoxycholic acid sodium salts or phospholipid completely restored the inhibitory effect of LysoPC on hydrolysis by lipase. On the other hand, the change in these kinetic values between the lipase and two 1-monoacylglycerols (1-monocaprin and 1-monoolein) were not particularly large when LysoPC was added. Particle size analysis of the lipid emulsion composed of LysoPC and triacylglycerols showed that most of the particles were less than 200 nm in size, which was smaller than the particle size in the triacylglycerol emulsions containing bile salts or phospholipid. The composition of the emulsion would affect its surface characteristics and thus contribute to changing lipase activity.

Polar organic solvent added to an aqueous solution changes hydrolytic property of lipase.

For developing further uses of lipase as a biocatalyst, its hydrolytic activity toward some esters was investigated in a miscible solution composed of a buffer and a polar organic solvent. Twenty percent dimethylformamide, 35% dimethylsulfoxide, 15% 1,4-dioxane, 15% dimethoxyethane, and 2% diethoxyethane promoted the hydrolysis by a lipase from Rhizomucor miehei toward some hydrophobic substrates, 4-methylumbelliferyl oleate, 4-methylumbelliferyl palmitate, and monoolein. While hydrolysis by this lipase toward the substrates with a relatively weak hydrophobicity (4-metylumbelliferyl heptanoate and 4-methylumbelliferyl nanoate) was suppressed by these solvents. A fluorometric analysis showed that the polar organic solvent in the buffer induced some conformational change around a tryptophan residue of R. miehei lipase. In addition to the influence of the miscible solvent on the solubility of the substrates, the conformational change of the protein induced by the miscible solvent would also affect the reactive properties of the lipase. Adding a polar organic solvent to an aqueous solution will be an efficient method for changing hydrolytic performance of lipases.

Fluorimetric analysis of lipase hydrolysis of intermediate- and long-chain glycerides.

For the purpose of deducing the digestive behavior of dietary fat in the digestive organs, a fluorimetric method for the measurement of hydrolysis by porcine pancreatic lipase was performed using intermediate- and long- acyl chain glycerides as substrates. Insoluble glycerides constituted by C10-C16 acyl chains were mechanically dispersed in 100% buffer and hydrolyzed by porcine pancreatic lipase. After the reaction, fatty acid released by the enzyme was extracted and its carboxyl group was fluorescently labeled with 9-bromomethylacridine. The 9-acridinylmethyl derivative of the fatty acid was separated and determined by HPLC. The sensitivity of this method was about 1000 times higher than that of the titrimetric method. Only 0.5 ng of porcine pancreatic lipase was sufficient for one routine assay. This assay method was successfully applied to investigate the enzymatic properties of porcine pancreatic lipase with respect to dietary lipids. The effects of some physiological factors concerned with lipid digestion, such as bile salt and colipase, on the lipase hydrolysis were also examined. The method established in the present study could contribute to a highly sensitive assay of some hydrolases containing lipase with regard to insoluble substrates.