Arsenic deficiency

Iron usually substitutes for some nickel and cobalt in skutterudite (Klein, 2002), 369. The arsenic in the crystalline structure of skutterudite occurs as AS4 rings (Cotton et al., 1999), 387. The rings are planar and rectangular with bond lengths of 2.464 0.002 A and 2.572 0.002 A at 22 °C (Mandel and Donohue, 1971). In skutterudite, each atom of cobalt or another divalent metal is surrounded by six arsenic atoms in a roughly octahedral formation (Mandel and Donohue, 1971). Chloanthite and smaltite are arsenic-deficient forms of nickel and cobalt skutterudite, respectively (Table 2.5). 

The semisynthetic ration of the goats contained 35 pg As kg DM, while the control animals received 350 pg As kg DM. All animals completed the trial for their natural life-span. In the first year of life, control and arsenic-deficient goats consumed similar amounts of feed (678 and 680 g/day). On average, the surviving adult arsenic-deficient goats ate 7% more semisynthetic ration than did controls (629 and 674 g/day, respectively) (Anke et al. 

Barren arsenic-deficient goats achieved an age of 6 years. Death regularly occurred between the 17th and 35th days of lactation typically, animals suffered spasms and died shortly thereafter. 

Arsenic deficiency also led to a significantly reduced ash content in the goat skeleton (Anke etal. 1976), while Uthus and Nielsen (1983) reported damage to the legs of chicks. A systematic investigation of the skeleton and cardiac muscles and liver of arsenic-deficient goats shortly before death... 

Anke M, Krause U and Groppel B (1987a) The effect of arsenic deficiency on growth, reproduction, life expectancy and disease symptoms in animals. In Hemphill DD, ed. Trace Substances in Environment Health — 21. University of Missouri, USA, pp. 533-550. 

Unexpected findings with animal feeds poor in inorganic arsenic and speculation of the possible essentiality of arsenic due to its position in the Periodic Table below phosphorus and next to selenium (both of which are known for their essential properties), led to the initiation of plans to study arsenic deficiency in experimental animals. Some earlier experiments, however, were unsuccessful as initially it was impossible to prepare correct arsenic-deficient diets. This was later achieved by Anke and coworkers (Anke et al. 1976a, b, 1987, 1990, 2001) in studies with goats and minipigs, and by researchers of the U S Department of Agriculture with rats, chicks and hamsters (Nielsen et al. 1975 cited in Uthus 1992, and reviewed by Uthus 1992, 1994, and Nielsen... 

No biological role has been demonstrated for mercury, other than its interaction with essential nutrients and toxicity (Natl. Research Council, 1978). Moderate growth stimulation by low dietary levels of cadmium has been described by Schwarz (1977) but not independently confirmed. Therefore, the following discussion will be limited to two trace elements, arsenic and lead, until recently known only for their toxicity. Arsenic deficiency has been produced in goats, minipigs, rats and chicken (Anke et al., 1976 Nielsen and Schuler, 1978 Uthus and... 

In a generalized sense, acids are electron pair acceptors. They include both protic (Bronsted) acids and Lewis acids such as AlCb and BF3 that have an electron-deficient central metal atom. Consequently, there is a priori no difference between Bronsted (protic) and Lewis acids. In extending the concept of superacidity to Lewis acid halides, those stronger than anhydrous aluminum chloride (the most commonly used Friedel-Crafts acid) are considered super Lewis acids. These superacidic Lewis acids include such higher-valence fluorides as antimony, arsenic, tantalum, niobium, and bismuth pentafluorides. Superacidity encompasses both very strong Bronsted and Lewis acids and their conjugate acid systems. 

One type of fatty liver that has been smdied extensively in rats is due to a deficiency of choline, which has therefore been called a lipotropic factor. The antibiotic puromycin, ethionine (a-amino-y-mercaptobu-tyric acid), carbon tetrachloride, chloroform, phosphorus, lead, and arsenic all cause fatty liver and a marked reduction in concentration of VLDL in rats. Choline will not protect the organism against these agents but appears to aid in recovery. The action of carbon tetrachloride probably involves formation of free radicals... 

The lower reactivity of 5a versus 10 reflects the stronger close packing of the anionic and cationic centers than that in the electron deficient cluster 10. Similar relations have been observed for analogous arsenic compounds (36). 

The research scientists recognized that they could not fulfill this mission by animal experiments alone. Employees at Edgewood Arsenal volunteered, but research deficiencies, including a lack of controls and the preconceptions of subjects familiar with the agents, limited the value of these studies. 

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