Showing papers in "Vitamins and Hormones Series in 1944"

Physiological Action of Vitamin E and Its Homologues

Abstract: Publisher Summary This chapter focuses on physiological action of vitamin E and its homologues. Studies have shown that the ability of plants to prevent the symptoms of vitamin E deficiency in animals is due solely to the presence of three higher alcohols for which the common designation of tocopherol has been given. None of the other organic compounds known to possess vitamin E action is found in the plant world. The methods used for their isolation from natural sources involved extraction with fat solvents, saponification, partition of the nonsaponifiable fraction between solvents, removal of sterols with digitonin, chromatographic analysis, vacuum distillation, and isolation as crystalline allophanates or as other esters. Molecular distillation from vegetable oils is used extensively for the commercial production of the natural tocopherols; the synthetic forms are readily prepared in the commercial laboratory. In this chapter, nature of vitamin E is elaborated. Chemistry of the tocopherols is discussed. Structural and functional disturbances due to lack of vitamin E is described in detail. Interrelationships of vitamin E with other vitamins are discussed as well.

The Role of Vitamins in the Anabolism of Fats

Abstract: Publisher Summary This chapter analyzes the possible effects of various vitamins upon the formation of complex lipids from much simpler molecules derived by metabolic processes from carbohydrates and proteins. A number of studies have dealt with the synthesis of lipids and with the effects of vitamins upon the synthesis and metabolism of lipids. Experimental studies have shown that several of the B vitamins are necessary for the in vivo synthesis of fats from carbohydrates or protein. Thiamin, riboflavin, and nicotinic acid have been proven to be constituents of enzyme systems which are essential for metabolism. Inositol has been shown to have a lipotropic action. Inositol is present in considerable amounts in some naturally occurring phospholipids, and it is possible that inositol, like choline, owes its lipotropic activity to participation in the formation of phospholipids. This chapter discusses classical demonstrations of fat formation. Synthesis of fat from carbohydrate is described, and formation of phospholipids is discussed. The chapter elaborated synthesis of fat from protein, and explains possible mechanism of fatty acid synthesis. Thiamin-sparing action of fats is described as well.

The nutritional requirements of primates other than man.

Abstract: Publisher Summary This chapter analyzes the nutritional requirements of primates other than man. Most of the experimental studies on the nutritional requirements of primates have been upon the rhesus monkey. Several investigators have restricted monkeys to a diet deficient in vitamin A, but in only a few of the animals were the classic eye signs of vitamin A deficiency were observed. Spontaneous rickets has been observed in young monkeys, and the disease has also been experimentally produced by feeding a diet deficient in vitamin D; the condition closely resembles rickets in the human infant. Monkeys also appear to be susceptible to osteomalacia. Experimental calcium deficiency has been produced in rhesus monkeys by the prolonged feeding of a diet deficient in this element, and a syndrome developed which was characterized by irritability, anorexia, weakness and muscular atrophy, and reduction in the calcium content of the bones. Neither the vitamin A nor vitamin D requirement of the monkey (or other primate species) has been determined.

Effect of Androgens and Estrogens on Birds

Abstract: Publisher Summary This chapter discusses the effect of androgens and estrogens on birds. Three of the commonly used androgenic substances known to occur naturally are androsterone, dehydroandrosterone, and testosterone. Certain other androgens isolated from natural sources, such as adrenosterone, androstadienone, and isoandrosterone are of much less importance in a consideration of the biological properties of this group of substances. A large number of compounds closely related to androsterone and testosterone, and showing androgenic activity, have been artificially prepared. The simplest members of the series differ from each other only in the permutations of keto- and hydroxy- groups in positions 3 and 17, in the spatial configuration of the hydroxyl group, and in the presence or absence of an unsaturated linkage in Ring A. This chapter describes androgenic substances and their effect on females and intact males. Effect on capons is described. Assay and relative activity of androgens on birds is explained. A detailed overview of estrogenic substances is presented. Effect of these substances on sex differentiation of the embryo is also analyzed.

X-Ray Crystallography and Sterol Structure

Abstract: Publisher Summary This chapter discusses X-ray crystallography studies of sterols. Sterols are widely distributed in nature and many of them are of much importance in biological processes. The use of X-ray methods described in the chapter has a wider interest as an illustration of the application of a new tool in chemical research. The crystal structures of cholesteryl chloride and bromide are closely related to those of cholesteryl iodide in the type of molecular packing present. The principal difference is a crystallographic one, the symmetry axis here being approximately parallel to, instead of approximately perpendicular to, the sterol ring system. The cholesteryl iodide variety is more suitable for detailed X-ray analysis, because the molecular projection shows in outline the sterol ring system. In crystal structures such as those of the phthalocyanines, the crystallographic evidence provides a direct determination of the molecular structure, which is entirely independent of chemical considerations. In this chapter, crystal structure of cholesteryl iodide is discussed. Crystal structure of choleeteryl chloride and bromide is explained. A classification of sterol crystal structures is also presented.

The Chemistry and Physiology of Vitamin A

Abstract: Publisher Summary This chapter discusses the chemistry and physiology of vitamin A. Chemical work on vitamin A depends on the establishment of biological activity. In the preparation of vitamin A concentrates by extraction from fish liver oils, the distribution of the vitamin can be adequately checked by determination of the ultraviolet absorption spectrum or even by use of the antimony trichloride test. The most commonly used criterion of response to vitamin A is the rate of growth (increase in body-weight) of young animals that have been fed exclusively on a vitamin-A-free diet for sufficiently long to have remained stationary in weight over an adequate period. With big enough groups of animals the average increase in weight should be a function of the amount of vitamin A given to supplement the basal diet. In this chapter, isolation of pure vitamin A is discussed. Measurement and distribution of vitamin A is described. The physiological action of vitamin A is elaborated. The chapter also discusses about synthesis of perhydrovitamin A and the possible isomers of Vitamin A.

Vitamins and Cancer

Abstract: Publisher Summary This chapter summarizes the diverse information available on the relation of vitamins to neoplasms. A great deal of research has been carried out on the effects of yeast and liver on the incidence and growth of various types of cancer. These materials are rich sources of vitamins of the B complex, and their influence on malignant growth has often been attributed to this high B complex content. The metabolism of tumor tissue is partially characterized by its high aerobic and anaerobic glycolysis. Because several of the flavoprotein enzymes have been shown to function in the transfer of hydrogen and electrons to molecular oxygen, it has been suggested that excess riboflavin might divert the metabolism of cancer tissues toward a more normal oxidative type. Vitamin C has not been observed to act as a prosthetic group, but its potential connection with enzyme action is well established. A controlling action on many of the hydrolytic enzymes has been demonstrated. In view of the reversible oxidation–reduction of ascorbic acid, it has been suggested that it may function as a hydrogen transfer system or as a regulator of cellular oxidation–reduction potential.

Para-Aminobenzoic Acid—Experimental and Clinical Studies

Abstract: Publisher Summary This chapter discusses experimental and clinical study results for para-aminobenzoic acid (PABA). PABA was first synthesized in 1863 by reduction of 4-nitro-benzoic acid with ammonium sulfide. The pure substance crystallizes in colorless needles which upon ageing, particularly under the influence of air and light, acquire a yellowish cast. It is freely soluble in alcohol or boiling water. At room temperature, one part of PABA may be dissolved in 200 parts of water. Among its incompatibilities are ferric salts and strong oxidizing agents. Although by itself without influence on the sense of touch or pain, practically all efficient local anesthetics are ester-like combinations of an amino alcohol with PABA or with another benzoic acid derivative. PABA has physiological activities that were intensely investigated as its role in pigmentation processes and its sulfonamide antagonism were postulated. In this chapter, an overview of experimental and clinical results for pigmentation process, toxicity and detoxication are presented. Qualitative and quantitative methods for determination of PABA are also elaborated.

The Chemistry of Biotin

Abstract: Publisher Summary This chapter presents an overview of the chemistry of biotin. By means of the extremely sensitive microbiological assay methods, biotin has been found to be widely distributed, and appears to be a common constituent of every type of living cell. In keeping with its high physiological activity, biotin is present in very low concentrations in living tissues. One of the richest sources, liver, contains less than 0.0001% of biotin. Such low concentrations of biotin make necessary the use of extremely large amounts of starting material for isolation procedures, and make the isolation of large amounts of the crystalline material difficult and almost prohibitive. Biotin has been found to be an essential factor in the biochemistry of many diversified types of living organisms. In the field of microorganisms, biotin has been found to be an essential growth substance for numerous strains of yeast, bacteria, and fungi. Of the microorganisms tested, those that do not require added biotin for growth have been found to possess the power to synthesize biotin.

A Critique of the Etiology of Dental Caries

Abstract: Publisher Summary This chapter discusses etiology of dental caries. A working hypothesis that each cavity arises as a result of a unique series of events is proposed to replace the current hypothesis that every cavity is the result of an identical series of causes or even from a single cause. The necessary revisions of procedures have been discussed. Caries indices and system of recording of dental caries have been criticized as concealing data. A system based on empirical sites of decay and maintenance of separation of data has been proposed. It is suggested based on dental caries in rats that fermentable carbohydrates do not initiate caries, although they do promote the enlargement of cavities by sustaining the activities of acidogenic organisms. This difference of action of carbohydrates is evidence that the mechanism of initiation of caries is distinct from that of cavity development. It is also suggested that structure of the enamel should be considered as an important factor in determining whether caries will be established.

Hormones in Cancer

Abstract: Publisher Summary This chapter discusses the role of hormones in cancer. Studies have shown that an enlargement of the prostate can be obtained in animals with estrone and that the enlargement can be reduced with testosterone. Prostatic tissue appears to be highly sensitive to sex hormones and particularly to estrone. Studies suggest that in the adult male rat, it is possible with sufficiently large doses to cause gross atrophy of the testes in a short while. It has been found that following the administration of estrogens, either in the form of naturally occurring hormones given subcutaneously, or by the administration of the synthetic analogues stilbestrol and hexestrol given by mouth, virtual disappearance of the symptoms, not only of the enlargement of the prostate, but also of the secondary deposits, may occur. This chapter analyzes sex hormones as carcinogens. It discusses estrogens and malignant disease of the prostate. Gonadotrophic substances and tumors of the testes are described. Role of hormones in mammary tumors is also elaborated.