Regulatory Problems

Kean (1970) found that CMP-sialic acid synthetase was located in the nuclei isolated from rat liver, kidney, brain, and spleen and hog retina. The subcellular location of this enzyme in the nucleus was well documented and is surprising in the light that CMP-sialic acid is utilized in a different geographic location in the cell (see Section III, C). This subcellular separation of the enzymes for synthesizing and utilizing CMP-sialic acid may represent an important control mechanism for sialic acid metabolism. 

Winterbum and Phelps (1970) have suggested that the L-glutamine-D-fructose-6-phosphate aminotransferase does not display classical feedback kinetic behavior in the presence of UDP-GlcNAc. Furthermore, they suggest that there is a 10-fold excess of enzyme over that necessary for a steady state for hexosamine metabolism. 

Similar experiments in bacteria, utilizing penicillin inhibition of the utilization of nucleotide sugars, led to an accumulation of the nucleotide sugar pools (Park and Strominger, 1957). These data suggest that bacterial systems lack a feedback mechanism. Komfeld (1967) was not 

FIGURE 6. Anabolic pathway for the synthesis of activated N-acetylglucosamine and sialic acid and proposed regulatory steps (Komfeld et aL, 1964). 

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REGULATORY PROBLEM AREAS AND POTENTIAL ENVIRONMENTAL VIOLATIONS... 

The public and the ethical industry are best served by decisions based on good science, adherence to high standards, and independent, expert review... If the industry starts with high quality science, effective analyses, and honest, responsive presentations, its regulatory problems will be few."... 

The symposium blended tutorial review papers with descriptions of field, laboratory, industrial, and regulatory problems that have been approached using chemical fate simulations. Authors presented current practices and practical questions such as material balance analysis, atmospheric processes influencing human exposure, aquatic system pathway analysis, movement in soil/groundwater media, and uptake or degradation in biota. 

Chadwick, J. and S. Reston. 1993. The regulatory problems in estimating the toxicity of wood preservatives to bats. Sci. Total Environ. 1993 Suppl. 1507-1512. 

Some companies have decided to avoid certain classes of compounds in their investigations simply because of the possibility that they will be plagued by regulatory problems due to the general character of their molecular structures (e.g. chlorinated hydrocarbons). One company has abandoned about 100 commercially interesting compounds since they have appeared on lists of suspected chemicals. Another company is backing off on all uses of chemicals which bring the chemicals in close proximity to food... 

Regulatory problems. Primary prevention shares some of these barriers with secondary prevention and mitigation, but these barriers are of different importance. 

Hydrocarbons and their transformations play a major role in chemistry. Industrial applications, basic to our everyday life, face new challenges from diminishing petroleum supplies, regulatory problems, and environmental concerns. Chemists must find answers to these challenges. Understanding the involved chemistry and finding new approaches is a field of vigorous development. 

Nelson, H. and R.D. Jones (1994). Potential regulatory problems associated with atrazine, cyanazine, and alachlor in surface water source drinking water. Weed. Technol., 8 852-861. 

More typically, instead of setpoint changes, the regulatory problem of responding to a system disturbance is encountered in commercial reactors. For this reason, the optimum tuning constants for the PID controller were developed from the IAE ralations for load disturbances. First, however, it is necessary to obtain a process model of the system. Brantley (10) has developed a process identification technique which fits process data to the second order plus dead-time form ... 

Government or regulatory problems (planning permission, patent infringement, process or product approval, illegal discharges. . . ). 

In recent years, there have been a number of examples of such problems (Table II.). The proposed data requirements for pesticide registration prepared by the U.S. Environmental Protection Agency address this topic. This has been an extremely controversial regulatory problem. It is clearly important to know the composition of applied pesticides including the major associated contaminants in order to assess their potential for environmental impact, but as the quantitative significance of... 

Multiple absorbants have been researched, and they include digitonin, tomatine, sodium cholate (bile salts), and active carbon (45, 47, 50). Most will face severe food regulatory problems. New Zealand (48) performed extensive research on active carbon, carbon impregnated with different metal salts, and inert supports impregnated with selected organic compounds. This technique (active carbon) is... 

To appreciate the regulatory problems this approach leads to, it is important to understand that risk assessment was developed as a tool for carrying out risk management, rather than a scientific process for understanding risk. Thus, both the selection of the data to be used and the way these data are extrapolated to the usual human exposure situation, reflect both scientific and policy considerations. As a result, risk assessment results do not represent the best scientific estimates of risk, estimates that are subject to scientific consensus, but rather prudent values that incorporate margins of safety. These margins of safety are included to increase the likelihood that regulations based on these risk assessments will successfully protect the public and the environment. 

The yeast produced by continuous culture techniques is separated from the liquid medium and solvent washed by centrifugation or filtration techniques. After drying, a protein supplement is obtained, which contains 65-68% protein and is suitable for addition to animal feeds. This protein content compares very favorably with that of dry fish meal, which contains about 65%, and dry skim milk powder with about 32%. The SCP processes have operated on the thousands of tonne/year scale in the U.K., France, and Italy, but regulatory problems with facilities operating on unpurified gas oil feedstocks have caused some shutdowns [64]. Nevertheless, because of a cell mass doubling time of 2.5-3 hr and the efficient carbon conversion to protein of this technology, these developments deserve to be explored further. 

The Board on Radioactive Waste Management summarizes the problems surrounding the setting of an EPA standard for radionuclides and the regulatory problems inherent in meeting such a standard. 

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