Nickel biology

Costing JS, Lemmens AG, Vandenberg GJ, et al. 1991. Iron, copper and zinc status in rats fed supplemental nickel. Biological Trace Element Research 31(1) 63-70. 

Conversion of the nitrile to the amide has been achieved by both chemical and biological means. Several patents have described the use of modified Raney nickel catalysts ia this appHcation (25,26). Also, alkaH metal perborates have demonstrated their utiHty (27). Typically, the hydrolysis is conducted ia the presence of sodium hydroxide (28—31). Owiag to the fact that the rate of hydrolysis of the nitrile to the amide is fast as compared to the hydrolysis of the amide to the acid, good yields of the amide are obtained. Other catalysts such as magnesium oxide (32), ammonia (28,29,33), and manganese dioxide (34) have also been employed. 

ANSI/ADA specification no. 14 provides a requirement for removable partial dentures of a combined minimum of 85% by weight of chromium, cobalt, and nickel or, for alloys failing to meet that minimum, at least 20% chromium. Bio-compatibiUty is demonstrated by passing the pertinent criteria of ANSI/ADA specification no. 41, Recommended Standard Practices for Biological Evaluation of Dental Materials. 

Until the discovery in 1975 of nickel in jack bean urease (which, 50 years previously, had been the first enzyme to be isolated in crystalline form and was thought to be metal-free) no biological role for nickel was known. Ureases occur in a wide variety of bacteria and plants, catalyzing the hydrolysis of urea,... 

Sarkar, N. K., Graves, R. A., and Park, J. R. Corrosion of Nickel-Chromium Casting Alloys in Selected Biological Media , Journal of Dental Research, 66, 206 (Abstr. 793) (1987)... 

Cammack, R. Catalysis by Nickel in Biological Systems Marcel Dekker New York, 1993. 

Aqueous standard solutions are a source of certain difficulties In electrothermal atomic absorption spectrometry of trace metals In biological fluids The viscosities and surface tensions of aqueous standard solutions are substantially less than the viscosities and surface tensions of serum, blood and other proteln-contalnlng fluids These factors Introduce volumetric disparities In pipetting of standard solutions and body fluids, and also cause differences In penetration of these liquids Into porous graphite tubes or rods Preliminary treatment of porous graphite with xylene may help to minimize the differences of liquid penetration (53,67) A more satisfactory solution of this problem Is preparation of standards In aqueous solutions of metal-free dextran (50-60 g/llter), as first proposed by Pekarek et al ( ) for the standardization of serum chromium analyses This practice has been used successfully by the present author for standardization of analyses of serum nickel The standard solutions which are prepared In aqueous dextran resemble serum In regard to viscosity and surface tension Introduction of dextran-contalnlng standard solutions Is an Important contribution to electrothermal atomic absorption analysis of trace metals In body fluids. 

Some nickel compounds may be irritant to skin and eyes and dermal contact with nickel can result in allergic contact dermatitis. Nickel carbonyl is extremely toxic by inhalation and should be handled in totally enclosed systems or with extremely efficient ventilation. Air monitors linked to alarms may be required to detect leaks. Respiratory equipment must be available for dealing with leaks. Biological checks (e.g. nickel in urine) should be considered for routine operations involving nickel catalysts. 

Fig. 4.14 SEM micrograph of CVD nickel-coated carbon microfibers (INCOEIBER 12K20) before (a) and after (b) the cathodic electrosynthesis of ZnSe on their surfaces (the scale bar is 8 and 10 p.m, respectively). Such low-dimensional substrates find apphcation in new-generation photovoltaic solar cells, chemical/biological sensors, and light-emitting devices. (Reprinted from [127], Copyright 2009, with permission from Elsevier)...

It has been reported that nickel catalyzed the reactions of 6-amino-1,3-dimethyluracil with substituted alkynylketones in water to give substituted 2,4-dioxopyrido[2,3-f/ pyrimidine derivatives in quantitative yields at room temperature (Eq. 4.70).134 The products have potential pharmacological and biological activities. The reaction may have proceeded through an ionic process. 

For the known nickel sites in biological systems, four-coordinate square planar, five-coordinate, and six-coordinate octahedral geometries are found.1840-1846 In general, the flexible coordination geometry of nickel causes its coordination properties in metallo-biomolecules to be critically influenced by the protein structure. 

Biomimetic chemistry of nickel was extensively reviewed.1847,1848 Elaborate complexes have been developed in order to model structural and spectroscopic properties as well as the catalytic function of the biological sites. Biomimetic systems for urease are described in Section 6.3.4.12.7, and model systems for [Ni,Fe]-hydrogenases are collected in Section 6.3.4.12.5. 

Variation of the content of impurities in the different CNT preparations [21] offers additional challenges in the accurate and consistent assessment of CNT toxicity. As-produced CNTs generally contain high amounts of catalytic metal particles, such as iron and nickel, used as precursors in their synthesis. The cytotoxicity of high concentrations of these metals is well known [35, 36], mainly due to oxidative stress and induction of inflammatory processes generated by catalytic reactions at the metal particle surface [37]. Another very important contaminant is amorphous carbon, which exhibits comparable biological effects to carbon black or relevant ambient air particles. 

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