Biomedical subjects
J Mauger
Publications and source records attributed to J Mauger.
The role of prehospital surgical cricothyroidotomy and methods of tracheal intubation.
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A novel nitrilase, arylacetonitrilase, of Alcaligenes faecalis JM3. Purification and characterization.
A new type of nitrilase, arylacetonitrilase, has been purified from isovaleronitrile-induced cells of Alcaligenes faecalis JM3 in four steps. The purity of the enzyme was confirmed by SDS/polyacrylamide gel electrophoresis, ampholyte electrofocusing and double immunodiffusion in agarose. The enzyme has a molecular mass of about 275 kDa and consists of six subunits of identical molecular mass. The purified enzyme exhibits a pH optimum of 7.5 and a temperature optimum of 45 degrees C. The enzyme is specific for arylacetonitriles such as 2-thiophenacetonitrile, p-tolyacetonitrile, p-chlorobenzylcyanide, p-fluorobenzylcyanide and 3-pyridylacetonitrile. The enzyme stoichiometrically catalyzes the hydrolysis of arylacetonitrile to arylacetic acid and ammonia, no formation of amide occurring. However, the enzyme does not attack nitrile groups attached to aromatic and heteroaromatic rings, which are hydrolyzed preferably by the nitrilases known previously. The enzyme requires thiol compounds such as dithiothreitol and 2-mercaptoethanol to exhibit its maximum activity.
Nitrile Hydratase-Catalyzed Production of Nicotinamide from 3-Cyanopyridine in Rhodococcus rhodochrous J1.
Nitrile hydratase, which occurs abundantly in cells of Rhodococcus rhodochrous J1 isolated from soil samples, catalyzes the hydration of 3-cyanopyridine to nicotinamide. By using resting cells, the reaction conditions for nicotinamide production were optimized. Under the optimum conditions, 100% of the added 12 M 3-cyanopyridine was converted to nicotinamide without the formation of nicotinic acid, and the highest yield achieved was 1,465 g of nicotinamide per liter of reaction mixture containing resting cells (1.48 g as dry cell weight) in 9 h. The nicotinamide produced was crystallized and then identified physicochemically. The further conversion of the nicotinamide to nicotinic acid was due to the low activity of nicotinamide as a substrate for the amidase(s) present in this organism.
Evaluation of a tube method for determining diffusion coefficients for sparingly soluble drugs.
Evaluation of a non-steady state method using glass tubes for the determination of diffusion coefficients is the purpose of this study. Unlike capillaries, glass tubes accommodate a larger volume of solution, facilitating assay procedures. Tubes are more susceptible to convection than are capillaries, but this effect is anticipated and accounted for in experimental design and data treatment. Glass tubes, 66 or 90 mm in length and 2 mm outer diameter, were siliconized and then filled with aqueous drug solution and placed in a jacketed flask containing gently stirred solvent at 25 degrees C. Diffusion experiments were run from 140 to 168 hours. At the end of this time period, the tubes were removed from the flask, placed in an ultrasonic vibrator for one minute, and their contents assayed spectrophotometrically. Data collected using potassium chloride as the diffusant showed little tube-to-tube variability, demonstrating the precision of the tube method, while diffusion coefficients determined for benzoic acid and p-aminobenzoic acid using the tube method tested the accuracy of the method by comparing reasonably well with values obtained using standard methods such as the rotating disk, free boundary, and membrane cell. Experiments done with either hydrocortisone or sulfisoxazole as the diffusant demonstrated the appropriateness of the tube method for the study of the diffusion of sparingly soluble pharmaceutical solutes.
Suspending agent effects on steroid suspension dissolution profiles.
Dissolution profiles and particle-size analyses were determined for two lots of prednisolone acetate. The effects of common suspending agents on dissolution and particle-size distributions of these suspensions also were investigated. Lot-to-lot variation in the prednisolone acetate dissolution rate was observed and was apparently related to the percentage of fine particles within the distribution. Carboxymethylcellulose sodium inhibition of prednisolone acetate dissolution occurred with only one lot of raw material and seemed to be related to aggregation of the fine particles. Hydroxypropyl methylcellulose inhibited both prednisolone acetate lots and was observed with or without small particle aggregation. The dissolution variations observed have important implications in suspension formulation.
Model systems for dissolution of finely divided (multisized) drug powders.
Several reports have dealt with model systems for the dissolution of log-normally distributed powders. A numerical solution is presented for the previously published Higuchi-Hiestand equations for a log-normal particle-size distribution. This solution was realized via an application of the System 360 Continuous System Modeling Program (CSMP). The resulting computer-aided calculations were utilized in the comparisons between the Higuchi-Hiestand model and other existing models. These comparisons provided a basis for the development of an adaptation of the Nielsen moving sphere model for log-normally distributed powders. The adaptation of the Nielsen equation for multisized particle systems is suggested as being potentially useful for treating experimental data where hydrodynamic effects must be considered.
[From public to private practice.].
The author explains the reasons he dropped out of the public sector.