A Comparison of Two Variational Methods

A discussion is given of the relation between the maximum functionaltheorem and Schwinger's variational principle, and it is shownthat the bound given by Schwinger's principle is better thanor the same as that given by the maximum functional theorem.     

Further Gurtin-type Variational Principles for Linear Initial Value Problems

Following the variational principles for linear initial valueproblems associated with the wave and heat conduction equationsdiscussed by Gurtin and Leitmann and using time convolutionsit is shown that general variational principles exist for theseproblems with sources on the boundaries and within the regionunder consideration.     

Modified Locally One Dimensional Methods for Parabolic Partial Differential Equations in Two Space Variables

In this note we consider the locally one dimensional methodas discussed in Gourlay & Mitchell (1969, 1972) and indicatehow this scheme can be used to solve accurately a parabolicpartial differential equation in two space variables.     

Ammonium detoxifying activity is maintained after 72 hours of cold preservation of rat hepatocytes in University of Wisconsin (UW) solution

The ammonium removal efficiency (ARE) and cell viability was investigated in freshly isolated rat hepatocytes exposed to increasing ammonium loads (0.1-2.0 mM). No difference was observed in both ARE and cell viability at the different ammonium concentrations tested. Storage of hepatocytes at 0 degrees C for 72 hours inhibited ammonium removal and urea synthesis. Rewarming of cells at 37 degrees C for 120 min was followed by an ARE fully comparable to freshly isolated hepatocytes. These data indicated that cold preservation of rat hepatocytes for 3 days in UW followed by a rewarming is associated with normal ammonium detoxification efficiency.     

A simple GC method for determination of cryoprotector diols 1,4-butanediol or 2,3-butanediol in isolated rat hepatocytes

We devised a simple method for determining the cryoprotectant agents 1,4-butanediol or 2,3-butanediol in isolated rat hepatocytes. After extraction of of hepatocytes with water (containing internal standard - ethylene glycol 1.25 mg/mL) the diol content was analyzed by gas chromatography. The method shows a linear response in the range 0.125 to 2.50 mg/mL for 1,4-butanediol and 0.25 to 3.75 mg/mL for 2,3-butanediol. The accuracy and precision of the method were evaluated and the coefficients of variation were found to be within = 6.0 %. The recoveries from hepatocyte samples containing 0.50, 1.00 and 2.00 mg/mL were 91.0 to 108 % for 1,4-butanediol and 80.6 to 100.3 % for 2,3-butanediol, respectively. This method allowed the determination of the intracellular concentration of diols in hepatocytes preserved for up to 120 hours at - 4 (C in UW solution + 8 % w/v 1,4-butanediol (or 2,3-butanediol).