Excretory products

M.p. 207°C. The naturally occurring substance is dextrorotatory. Arginine is one of the essential amino-acids and one of the most widely distributed products of protein hydrolysis. It is obtained in particularly high concentration from proteins belonging to the prolamine and histone classes. It plays an important role in the production of urea as an excretory product. 

Dietary additives can affect the microbiota that are associated with the faeces of animals and degradation of the faeces may be impaired because of the influence of the excretory products on insects, microbes and fungi. The microbiota in the soil and waste material may be affected, thus altering the fertility of the pasture and sustainability of other wildlife. These microbiota can be used as dietary ingredients for animals, so inhibition of their production would be an unsatisfactory consequence of dietary additives. ... 

The metabolic fate of chlordan was studied in rabbits by analysis of the relative chlorine content of chlordan added to normal rabbit s urine and of the chlorine content of the urinary excretory product. The method of analysis was similar to the one previously used (, 4) In addition, hydrolysis of chlordan and of the urinary excretory products was carried out by adding solid sodium hydroxide to saturation to a 10-ml. solution of these substances in hot absolute ethyl alcohol. The mixture was refluxed for 3 hours in a round-bottomed flask immersed in boiling water and the amount of inorganic chlorine determined. Hydrolysis was similarly carried out with solutions of the respective substances in aqueous sodium hydroxide. 

The fluid portion of the blood, the plasma, accounts for 55 to 60% of total blood volume and is about 90% water. The remaining 10% contains proteins (8%) and other substances (2%) including hormones, enzymes, nutrient molecules, gases, electrolytes, and excretory products. All of these substances are dissolved in the plasma (e.g., oxygen) or are colloidal materials (dispersed solute materials that do not precipitate out, e.g., proteins). The three major plasma proteins include ... 

Data on absorption across the gastrointestinal tract indicate that hexachloroethane is absorbed, but the percentage of a dose that is absorbed varies. Absorption estimates based on excretory products in rabbits suggest that a moderate portion of a 500 mg/kg dose (perhaps 40-50%) is absorbed. Data on excretory products from rats and mice indicate that a much larger portion (62-88%) of this same dose is absorbed. 

The biosynthesis and metabolism of nicotinic acid in disease has received little attention metabolic studies deal mainly with normal animals and man (01, R5). After a tryptophan load dose, the main catabolites in the urine are nicotinuric acid, N1-methylnicotinamide, nicotinamide, quinolinic acid, kynurenine, 6-pyridone, anthranilic acid, and 3-hydroxyanthranilic acid. These excretory products were estimated... 

Recently, tritiated folic acid became available, making possible a nonmicrobiological method for studying the metabolism of folic acid. It obviates the toxic effects of folic acid antagonists on microbial assay organisms. This technique was used to follow the uptake, metabolism, and excretory products of folic acid (A4, J2, J3). 

Today, manure refers to excretory products of animals and finds its most common usage in reference to farm animals. This organic material was and is used as fertilizer to provide necessary elements for plants. In the past, it was practically the only material readily available for increasing plant or crop production. The general idea, however, is to add something to soil that will improve plant production. Thus, it remains common in popular agriculture literature to find that material added to soil to improve crop production is called manure even if the material is not organic [8,9],... 

Control of remetabolism. Contamination of bedding and coprophagy undoubtedly were drawbacks in earlier rodent work, but modern metabolism chambers remove excretory products rapidly. The excretory products of aquatics are released into the medium and so may be available for repeated reabsorption and remetabolism. 

Nitrogen is an important component of many biomolecules, such as proteins, amino acids, amino sugars, the aromatic bases in nucleotides, and the siderophores (Figure 5.11). Other nitrogen-containing compounds that have been found in seawater are excretory products such as creatinine, methylamine, urea, and uric acid (Figure 22.26). 

Catabolic pathways are degradative. Molecules of varying degrees of complexity are broken down to simpler cellular constituents or excretory products. These pathways... 

For birds, insects, and reptiles, which have an egg stage during development, so that water availability is severely restricted, the synthesis of a highly soluble excretory product would have serious osmotic consequences therefore most of the ammonia is converted to the virtually insoluble uric acid (urate). This product can be safely retained in the egg or excreted as a slurry of fine crystals by the adult. In birds that nest colonially this can accumulate in massive amounts on islands off the coast of Peru cormorants have deposited so much that this guano (hence the name guanine) is collected for use as a fertiliser. Uric acid is less effective as an excretory product, since it has a lower nitrogen content than urea (33%) and is more expensive to synthesise (2.25 molecules ATP per atom of nitrogen). Mammals do produce uric acid but as a product of purine catabolism (see above). 

Hassanali, A., McDowell, P. G., Owaga, M. L. A., and Saini, R. K. (1986). Identification of tsetse attractants from excretory products of a wild host animal, Syncerus coffer. Insect... 

The second phase of metabolism consists of synthetic reactions that convert active compounds into inactive excretory products. Drugs that contain suitable chemical groups, such as —OH, —NHa, or —COOH, can undergo these synthetic conjugation reactions if not present in the parent compound, such drugs may be introduced during phase one reactions. Phase one and phase two metabolic reactions occur sequentially. 

Cresols are an excretory product of mammals and an intermediate biotransformation product of natural aromatics such as lignin constituents (Fiege and Bayer 1987). Consequently, soil microorganisms are capable of metabolizing cresols, and any anthropogenic release of cresol, other than massive spills, is likely to be rapidly degraded in soil (Section 5.3.2.3). 

The secretion from the prothoracic glands of the lacewing Chrysopa oculata (Chrysopidae) contains skatole (140) and tridecene (Table VIII) and offers some protection against invertebrate predators, such as ants. Uric acid (95) is stored as one of the excretory products of nitrogenous metabolism in fat bodies of the larvae of C. carnea (Table VI). 

Excretion. No information was located regarding specific mechanisms of excretion of chlorine dioxide, chlorite, or their metabolites. However, since chloride ion is the primary excretory product of chlorine dioxide and chlorite, excretory mechanisms would be expected to be similar to those responsible for excretion of other ions. 

Allantoin is the excretory product in most mammals other than primates. Most fish hydrolyze allantoin to allantoic acid, and some excrete that compound as an end product. However, most continue the hydrolysis to form urea and glyoxylate using peroxisomal enzymes.336 In some invertebrates the urea may be hydrolyzed further to ammonia. In organisms that hydrolyze uric acid to urea or ammonia, this pathway is used only for degradation of purines from nucleotides. Excess nitrogen from catabolism of amino acids either is excreted directly as ammonia or is converted to urea by the urea cycle (Fig. 24-10). 

Pyrimidines and purines derivatives act as bases and can be acquired through the diet. In particular, organ meats such as liver are a rich source of DNA and RNA. Most dietary purines are oxidized by enzymes to uric acid in the intestinal mucosa that is their excretory product in humans. The desease known as gout is related to high levels of uric acid in serum and the result of deposition of urate salts in various tissues. 

Another form of detoxified ammonia that is used in nitrogen excretion is uric acid. Uric acid is the predominant nitrogen excretory product in birds and terrestrial reptiles (turtles excrete urea, whereas alligators excrete ammonia unless they are dehydrated, in which case they, too, excrete uric acid). Uric acid formed as a product of amino acid catabolism involves the de novo pathway of purine biosynthesis therefore, its formation from NH3 liberated in amino acid catabolism is described elsewhere (see chapter 23). In mammals, uric acid is exclusively an intermediate in purine... 

Degradation of uric acid to excretory products. Mammals other than primates oxidize uric acid further to allantoin. Humans and other primates as well as birds lack urate oxidase and hence excrete uric... 

Several factors are involved in the sensitivity of the kidney to a number of toxicants (Table 15.1), although the high renal blood flow and the increased concentration of excretory products following reabsorption of water from the tubular fluid are clearly of major importance. Although the kidneys comprise less than 1% of the body mass, they receive around 25% of the cardiac output. Thus significant amounts of exogenous chemicals and/or their metabolites are delivered to the kidney. 

There have been studies of the metabolism of DEHP in humans after oral exposures as reflected by its urinary excretory products. In two volunteers exposed to 30 mg DEHP, metabolites I, II, III, IV, V, VI, VII, and VIII were identified in the urine by mass spectroscopy (Schmid and Schlatter 1985). MEHP accounted for 6-12% of the measured metabolites. Metabolite VI was approximately 20% of the excreted material, Metabolite IX approximately 30% and Metabolite V approximately 30%. The remaining metabolites were each less than 5% of the excreted material. Based on a comparison of the metabolites in the hydrolyzed urine as compared to the unhydrolyzed urine, approximately 65% of DEHP metabolites are excreted as glucuronide conjugates in humans. Each of these major metabolites is the product of oxidation of a different carbon in the 2-ethylhexyl substituent. 

The data from animal studies demonstrate that DEHP and it metabolites are excreted in both the urine and the feces. Rats exposed to 50-300 mg/kg DEHP excrete 32-70% of the dose in the urine as metabolites (Astill 1989 Ikeda et al. 1980 Short et al. 1987). An additional 20-25% of the absorbed dose was excreted with the bile in the fecal matter. The remainder of the fecal excretion was unabsorbed DEHP and MEHP. In monkeys, approximately 30% of a 100 mg/kg dose and 4% of a 2,000 mg/kg dose were excreted in the urine (Astill 1989 Rhodes et al. 1986 Short et al. 1987 Sjoberg et al. 1985b). The remainder was in the feces. A portion of the fecal metabolites was contributed by the bile. The biliary excretory products represent approximately 15% of the absorbed DEHP. In rats and mice administered radiolabeled DEHP, 85-90% of the label was excreted in the first 24 hours (Astill 1989 Ikeda et al. 

Fig. 5.6. Proton decoupled 13C n.m.r. spectrum at 75.47 MHz of the excretory products of Hymenolepis dimimta fed D-[6-13C]glucose. p.p.m., parts per million. (After Blackburn et al, 1986.)...

Table 6.7. Nitrogen excretory products of cestodes. (Data from Smyth, 1969)... 

Excretory product Hymenolepis diminuta Echinococcus granulosus0 Cysticercus tenuicollis0 Lacistorhynchus tenuis Taenia taeniaeformisa... 

Blackburn, B. J., Hutton, H. M., Novak, M. Evans, W. S. (1986). Hymenolepis diminuta nuclear magnetic resonance analysis of the excretory products resulting from the metabolism of D-[13C6]glucose. Experimental Parasitology, 62 381-8. 

Developmental physiology of cestodes. XVI. Effects of certain excretory products on incorporation of [3H]thymidine into DNA of Hymenolepis diminuta. Journal of Experimental Zoology, 211 55-61. 

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