Using computer algebra to determine rate constants in biochemistry

In earlier work we have described how computer algebra may be used to derive composite rate laws for complete systems of equations, using the mathematical technique of Gröbner Bases (Bennett, Davenport and Sauro, 1988). Such composite rate laws may then be fitted to experimental data to yield estimates of kinetic parameters. Recently we have been investigating the practical application of this methodology to the estimation of kinetic parameters for the closed two enzyme system of aspartate aminotransferase (AAT) and malate dehydrogenase (MDH) (Fisher 1990a; Fisher 1990b; Bennett and Fisher, 1990): $$\begin{gathered} aspartate + \alpha - ketoglutarate\begin{array}{*{20}c} \rightharpoonup \\ \leftharpoondown \\ \end{array} glutamate + oxaloacetate \hfill \\ {\text{oxaloacetate + NADH}}\begin{array}{*{20}c} \rightharpoonup \\ \leftharpoondown \\ \end{array} malate + NAD^ + \hfill \\ \end{gathered} $$ In this paper we present a fuller (although not yet complete) analysis of the system. We show how symbolic estimates of the error behaviour of the parameters can be made, and used to identify those which are of kinetic significance. Finally we consider how metabolic control analysis can be applied directly to such a system.     

Cytochemical study of various enzymes of the rabbit crystalline lens epithelium]

The activity of a number of enzymes of glycolysis, tricarbonic acids, cycle, pentose phosphatase shunt and some important hydrolases, acid nucleases and adenosine triphosphate among them, was cytochemically determined in the rabbit lens epithelium. The data obtained clearly demonstrate the role the epithelium plays in energy producing processes of the lens, which are connected both with anaerobic and aerobic phases of glucose utilization and its direct oxydation, as well as with synthesis of some substances, with the transport of organic and inorganic molecules.     

Influence of variations in blood pH on the bronchodilator action of salbutamol and terbutaline]

In the cat, the broncho-dilatator effects of salbutamol and terbutaline are influenced by blood pH variations. Gazeous or metabolic alkalosis increases, acidosis decreases, the broncho-dilatation provoked by salbutamol or terbutaline.     

Study of the immunological activity of blood in various rickettsial and viral infections]

The content of various types of antibodies were studied in the blood serum of laboratory animals in experimental tick-borne rickettsiosis of Northern Asia. This was done by a simultaneous staging of indirect hemagglutination, indirect hemolysis, compliment fixation under cold conditions, and agglutination with Proteus antigen OX19 tests. Immune horse sera to the influenza virus were also studied with the aid of several serological tests. The data obtained pointed to the significant differences in the properties of individual types of antibodies. Immunological activity of the sera under study depended on the correlation in them of various types of antibodies at various periods of the infectious process in combination with the influence upon the immunogenesis of the individual and species immunological reactivity.     

On various possibilities in pulsed radiation biochemistry and chemistry

Several experiments are described that relate to the application of new regimes of radiation action on enzymes in vitro and some other materials. These regimes have recently come into practice due to the appearance of a new generation of devices with very short high-energy pulses of ionizing radiation. It is shown that the term flash radiation biochemistry in its perfect sense has to be used at the condition of the overlapping individual effective interaction microvolumes (e.g. spurs and blobs) realized during a time interval (radiation pulse duration) that is low compared with the corresponding physical-chemical process. In this situation a number of unexpected effects occur at very low absolute doses. These processes are analyzed in terms of their non-stationary and non-diffusive developments.     

Universal measuring site for the determination of tissue-impedance variations in relation to blood perfusion]

In view of the importance of impedance plethysmography requirements are formulated for a modern impedance measuring device basing on a long experience with this method of measurement. The principle mode of action of the measuring equipment and the pneumatics with the timing element are described. A number of recordings is shown to illustrate the universality of the measuring equipment.     

Photoperiodic variations in plasma concentration of testosterone in the rabbit

The photoperiodic variations of testosterone plasmatic levels in male rabbits have been studied. The animals were subjected to the influence of three circadian rhythms: 12/12, 14/10 and 10/14 h of light/darkness. The hormone assay was carried out using an enzymeimmunoassay method (Competitive ELISA). Blood samples were of two different types: seriated and non-seriated, to find if these might be any differences in the results. It is concluded that testosterone plasmatic levels are within physiologic values (0.3-10.0 ng/ml), although differences depending on the light/darkness cycle and on the type of blood extraction are remarkable; for this reason the selection of the circadian rhythm will depend on the experimentation that is to be carried out.     

Brain lipid biochemistry of the sturgeons Acipenseridae]

Brain lipids of 4 species of sturgeons-Acipenser güldenst?dti, A. stellatus, A. ruthenus and Huso huso-have been investigated. In whole brain homogenates the content of the basic phospholipid families, their fatty acid composition as well as the content of glycosphingolipids-gangliosides, cerebrosides and sulfatides were studied. The quantitative relations between different molecular ganglioside fractions and their fatty acid composition, as well as the relative content of hydroxycerebrosides and cerebrosides with normal fatty acids were determined. The brain lipids of Acipenseridae were compared to previously obtained data on the brain of Elasmobranch and Teleost fishes. The brain lipid pattern of the four sturgeon species is very similar, but it differs greatly from that of Elasmobranch and of Teleostean brain, being in some respect more like the type of bony fish brain, in others the kind of brain of sharks and rays, and frequently considerably differing from both these types. The conspicous peculiarity in the content and molecular characteristics of the brain lipids of Acipenseridae compels us to agree with the opinion expressed by the late A.N. Belozerski and his coworkers [26, 27], based on a detailed study of fish DNA nucleotides, that the Ganoid fish are to be regarded as an independent class.     

Photoperiod,stress and the distribution of leukocytes in the peripheral blood ofNotophthalmus viridescens

Summary Adult newts,Notophthalmus viridescens, were maintained for 8 days at a constant temperature of 11.0±0.5 °C. In one series, the control animals were kept in constant darkness (DD), while the experimental newts were exposed to alternating 12-hour periods of light and dark (LD). In a second series, controlNotophthalmus lived in DD, and experimental animals lived in constant light (LL). In both series, the newts were sacrificed on the ninth day when blood smears were prepared. Differential counts of the leukocytes of animals that lived under the LD regimen were the same as those of controlNotophthalmus (Table 1). However, in newts that were maintained in LL, the neutrophils increased and the lymphocytes decreased relative to those types of cells in the controls (Table 1). Those changes indicate that continuous light constitutes stress for this species.Supported in part by a grant from the Committee on Research, Travel and Sabbatical Leaves, Colby College