Vitamin hormone

Many pharmaceutical compounds contain chromophores that make them suitable for analysis by UV/Vis absorption. Products that have been analyzed in this fashion include antibiotics, hormones, vitamins, and analgesics. One example of the use of UV absorption is in determining the purity of aspirin tablets, for which the active ingredient is acetylsalicylic acid. Salicylic acid, which is produced by the hydrolysis of acetylsalicylic acid, is an undesirable impurity in aspirin tablets, and should not be present at more than 0.01% w/w. Samples can be screened for unacceptable levels of salicylic acid by monitoring the absorbance at a wavelength of... 

More than 99% of total body calcium is found in bone the remaining less than 1% is in the ECF and ICE Calcium plays a critical role in the transmission of nerve impulses, skeletal muscle contraction, myocardial contractions, maintenance of normal cellular permeability, and the formation of bones and teeth. There is a reciprocal relationship between the serum calcium concentration (normally 8.6 to 10.2 mg/dL [2.15 to 2.55 mmol/L]) and the serum phosphate concentration that is regulated by a complex interaction between parathyroid hormone, vitamin D, and calcitonin. About one-half of the serum calcium is bound to plasma proteins the other half is free ionized calcium. Given that the serum calcium has significant protein binding, the serum calcium concentration must be corrected in patients who have low albumin concentrations (the major serum protein). The most commonly used formula adds 0.8 mg/dL (0.2 mmol/L) of calcium for each gram of albumin deficiency as follows ... 

Marcus, R., Agents affecting calcification and bone turnover calcium, phosphate, parathyroid hormone, vitamin D, calcitonin, and other compounds, in Goodman and Gilman s The Pharmacological Basis of Therapeutics, 9th ed., Hardman, J.G. and Limbird, L.E., Eds., McGraw-Hill, New York, 1996, chap. 61. 

The signal is what starts everything off. Signals take a variety of forms, but for our purposes there are only two. The first type are signals that go into the cell, bind to internal receptors, and exert their effects. Steroid hormones, vitamin D, thyroid hormone, and retinoids are the only members of this class. All of the intracellular receptors ultimately activate the transcription of regulated genes. The common feature of signals that enter the cell is that they are all small lipophilic molecules that can cross the cell membrane. 

Bone mineral metabolism agents Parathyroid hormone Vitamin D... 

Cytochrome P450 pathways in human brain cholesterol, steroid hormones, vitamin D, and bile... 

The table also lists important globulins in blood plasma, with their mass and function. The a- and p-globulins are involved in the transport of lipids (lipoproteins see p. 278), hormones, vitamins, and metal ions. In addition, they provide coagulation factors, protease inhibitors, and the proteins of the complement system (see p. 298). Soluble antibodies (immunoglobulins see p. 300) make up the y-globulin fraction. 

This mechanism is used by steroid hormones (Table 14—2), thyroid hormone, vitamin D3, and retinoic acid. 

FIGURE 23-22 The composition of blood. Whole blood can be separated into blood plasma and cells by centrifugation. About 10% of blood plasma is solutes, of which about 10% consists of inorganic salts, 20% small organic molecules, and 70% plasma proteins. The major dissolved components are listed. Blood contains many other substances, often in trace amounts. These include other metabolites, enzymes, hormones, vitamins, trace elements, and bile pigments. Measurements of the concentrations of components in blood plasma are important in the diagnosis and treatment of many diseases. 

There are many classes of natural and synthetic steroids best known for their wide array of biological activity. The naturally occurring steroids can be subdivided into several categories that include (7) nonhormonal, mammalian steroids (2) vitamin D (. ) hormonal steroids and (4) other naturally occurring steroids. See also Hormones Vitamin and Vitamin D. 

The daily requirements of vitamins by humans are summarized in the entiy on Diet. The relationship between hormones and vitamins is described in the entry 011 Hormones. Vitamins also are mentioned frequently in descriptions of various fruits, vegetables, and other foodstuffs throughout tlie book. Vitamins also figure prominently in discussions of some of the diseases, scores of which are described in this book. 

Plasma levels of some hormones (thyroid and steroid hormones), vitamins (vitamin D metabolites), ions (iron, copper, and zinc) and drugs maybe low in nephrotic subjects because of the low levels of protein-bound ligands (K11), as binding proteins are lost into the urine. Ligands also may be lost in the urine together with their... 

The permeability of the skin to a toxic substance is a function of both the substance and the skin. The permeability of the skin varies with both the location and the species that penetrates it. In order to penetrate the skin significantly, a substance must be a liquid or gas or significantly soluble in water or organic solvents. In general, nonpolar, lipid-soluble substances traverse skin more readily than do ionic species. Substances that penetrate skin easily include lipid-soluble endogenous substances (hormones, vitamins D and K) and a number of xenobiotic compounds. Common examples of these are phenol, nicotine, and strychnine. Some military poisons, such as the nerve gas sarin (see Section 18.8), permeate the skin very readily, which greatly adds to then-hazards. In addition to the rate of transport through the skin, an additional factor that influences toxicity via the percutaneous route is the blood flow at the site of exposure. 

Cholesterol is involved in two major biological processes. It is a structural component of cell membranes (Chap. 6) and the parent compound from which steroid hormones, vitamin D3 (cholecalciferol), and the bile salts are derived. Cholesterol is synthesized de novo in the liver and intestinal epithelial cells and is also derived from dietary lipid. De novo synthesis of cholesterol is regulated by the amount of cholesterol and triglyceride in the dietary lipid. 

Reviews a) H. F. DeLuca, J. Burmester, H. Dar-wish, J. Krisinger, Comprehensive Medicinal Chemistry, Pergamon, New York, 1990, Vol. 3, 1129 b) A. W. Norman, R. Bouillon, M. Thomas-set (eds.) Vitamin D Gene Regulation, Structure Function Analysis and Clinical Application, de Gruyter, Berlin, 1991 c) A. W. Norman, R. Bouillon, M. Thomasset (eds.) Vitamin D Chemistry, Biology and Clinical Application of the Steroid Hormone, Vitamin D workshop, Inc Riverside, CA. 1997. 

Lian JB, Stein GS, Stein JL, and van Wijnen AJ (1999) Regulated expression of the bone-specific osteocalcin gene by vitamins and hormones. Vitamins and Hormones 55, 443-509. 

Isoprenoids are one of the largest classes of natural products that comprise at least 35,000 reported members (48). Many of these compounds play crucial roles in human metabolism as hormones, vitamins (vitamins A, D, E and K), quinine-type cofactors of respiratory chain enzymes (ubiquinone), membrane constituents, and functionally important side chains of signal cascade proteins (Fig. 11). Chlorophyll (17, Fig. 2) and heme a (18) have isoprenoid side chains. 

---