Adipose tissue contains all metabolic pathways associated with somatic cells, but is highly specialized for the synthesis, storage and mobilization of FFA. This part of the thesis will summarize briefly concepts of adipose tissue metabolism as they have evolved during recent years. It will also consider some of the problems arising from the interpretation of the data derived largely by in vitro techniques.

The metabolism of the mature mammalian erythrocyte can be considered anomalous in relation to most types of somatic cells, including those from which the erythrocyte is derived. Erythropoiesis takes place mainly in the bone marrow, and is presumed to occur in the following stages: stem blast cell- erythroblast - normoblast - reticulocyte - erythrocyte. The cells up to and including the normoblast stage have a well defined nucleus, whereas the reticulocyte contains only stainable granules believed to be ribonucleoprotein. The mammalian erythrocyte lacks bath the nucleus and stainable granules.

The stimulation of nervous tissue leads first to excitation at the point of application, and from here the excitation is propagated to an effector organ which responds to the transmitter excitation. Prior to the first decade of 1900, there were only hypotheses which sought to suggest the intimate mechanism by which nervous excitation produces a functional change in an organ. Elliott, observing that the effect of stimulation of sympathetic nerves and of adrenaline was identical, proposed the hypothesis that stimulation of sympathetic nerves caused liberation of adrenaline and that it was the adrenaline which was responsible for the end effect of nervous stimulation. The question of whether nervous stimulation directly affected the organs involved was tested experimentally by Howell who indicated that stimulation of the vagus led to a liberation of potassium, this substance in turn causing the resulting phenomenon. Although Howell's assumption was not corroborated, he was the first to investigate experimentally the possible mechanism of the inhibitory function of a nerve. In the same year, Dixon cited evidence for the presence of a substance in heart tissue, "pro-inhibitin", which was converted to "inhibitin" on vagal stimulation. This substance, when combined with heart muscle, brought about cardiac arrest. [...]

The study of neurochemistry has tended to follow two main pathways. One of these, the isolation and characterization of the constituents of nervous tissue, had its beginnings over eighty years ago in the laboratory of J.L.W. Thudicum, the "Father of Neurochemistry". The other path has led to studies of the metabolism of nervous tissue, both in vitro and in vivo. It is the aim of most neurochemists to bring these two divergent paths into a closer alignment in arder to gain inaight into the unique function of this important tissue. The studies described in this thesis also follow two different paths. It is hoped that these two approaches complement each ether, however, and lead to a better understanding of the chemistry and the functional role of the gangliosides in nervous tissue. [...]

In 1888, de Rey Pailhade for the first time described a substance containing sulfur which he had been able to isolate from yeast in an impure state and he called this substance "Philothion". Hopkins in 1921, iso1ated from yeast cells a low molecular weight sulfur containing substance which he named "glutathione". Finding that the compound gave a positive nitroprusside reaction and contained glutamic acid and cysteine he concluded that it probably was a dipeptide of these amino acids. Eight years later Hunter and Eagles questioned the validity of the dipeptide structure and Hopkins was prompted to reinvestigate the constitution of the compound. With the aid of cuprous oxide as a reagent he was able to isolate glutathione as a copper derivative and from it to isolate glutathione itself in a crystalline form. On further analysis he found the substance to be a tripeptide consisting of glutamic acid, cysteine and glycine. Soon afterward Pirie and Pinhey performed for the first time the electrometric titration of the ionizable groups in glutathione and proposed the correct structure of the compound. This finding was confirmed by degradation studies and by the synthesis of the compound by Harington and Mead. [...]

Structural modification of normal metabolites has often led to compounds which no longer function normally but which interfere with the metabolism of the normal compound. A classical example of this phenomenon is the finding by Quastel and Wooldridge that malonate resembles succinic acid closely enough to inhibit succinic dehydrogenase. A glance through the recent treatise "Metabolic Inhibitors" (1) Will, convince the most skeptical reader of the importance of this approach in elucidating metabolic processes as well as in the field of chemotherapy. [...]

Proteins are naturally ocurring high polymeric substances in which the basic monomeric unit is the alpha amino acid. They are necessary components of all living matter and include on one hand the relatively inactive fibrous proteins like the collagens or bone and tendon and the keratins of hair; and on the other hand a great number of substances having a high degree of chemical and biological activities, globular proteins -- which include enzymes, hormones and the outer protein coat of viruses. It can be stated generally that only the known twenty-two different species of nataral amino acids have been found in protein molecules. [...]

The significance with wbich ACh is attributed in the role of a neurotransmitter is reviewed.The sparcity of the chemical evidence used to characterize ACh is described and this evidence is criticised. The difficulties which arise by assuming a general transmitter function for ACh are discussed and the alternatives are reviewed.It is pointed out that many cholinergie materials are present in the brain and ACh itself is often present in very small amounts.

Since the classical work of Metchnikoff in the 1880's, the important role played by phagocytic cells in the defense of the host against infectious disease has been recognized. It is now known that phagocytic cells in higher animals provide an effective defense mechanism against a wide variety of bacteria, fungi and protozoa.It has also been suggested that a mechanism closely analogous to phagocytosis may aid in the disposai of submicroscopic parasites and toxins of small molecular dimensions in the mammalian host. [...]

Whether from the standpoint of synthesis within the organism, or of absorption from the diet, glucose is quantitatively the most important carbohydrate available to the body for various purposes. To a considerable extent, therefore, the discussion of carbohydrates resolves itself into a consideration of the metabolism of glucose and its closely related derivatives. Glucose contributes a major part to the total energy production in most animal tissues. Several metabolic pathways are open to glucose: (a) conversion of glucose to glycogen for storage (b) utilization of glucose for energy production (c) utilization of glucose for the synthesis of other compounds, such as fatty acids and certain amino acids. [...]