Problems for the Future

The problem for the physiologist is to ascertain the details of the mechanism whereby chemically diverse substances produce apparently identical reactions, to discover the mode of action of the antibiotic substances, and to learn why some organisms are highly sensitive and others almost completely resistant to them. On the answer to these questions, among others, depends rational therapy with antibiotic substances. 

Waksman, S. A., Micro iial Antagonisms and Antibiotic Substances. Th( Common- 

The Amino Acid Decarboxylase-Pressor Amine-Amine Oxidase System 633 

Formation of Pressor Substances by Amino Acid Decarboxylase S 534 

Therapeutic Measures against Enzymically Formed Pressor Agents. 538 

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Some of the cyclic tetrapeptides investigated so far have been described in earlier parts of this article. In addition, Deber etd, 110) investigated C yclo-(Pro-Gly)2. Accordii to their investigation it was made clear that the peptide bonds of Cydo-(Pro-Gly)2 has a ds-trans-cis-trans sequence, and that one of the Pro-C —C = O bonds is cis p = —60°) and the other is tmns ip = 120°). and H NMR spectroscopies of Cyclo-(Pro-Gly)2 in D2O-CH3CN (9 1) or DMSO-d6-CD2Cl2 (2 5) mixed solvents showed that on heatup the solution the X-Pio bond remained cis but a slow cis —tram interconversion (AF 13—15 kcal/mol) of fto-C —C = O bond took (dace. This (dienomenon mi t be characteristic of relatively crowded cyclic tetrapeptides such as C ydo-(Pro-Gly)2. However, the slow cis —tram interconversion has not been observed with Cyclo-(D-Pro-Gly) and Cyclo-(Pro-Sar)2, which leaves the complete understanding of the problem for the future. Such a slow cis -tram interconversion would not be the case for larger cyclic peptides and linear peptides. 

The temptation of remaining satisfied with the generalization must be avoided- This monograph has been written in the most general terms, mainly to provide a simple account of the basic ideas on defect solids. The detail of even the simplest problem is still controversial, and herein is the problem for the future. 

But if this new biology is used only to divide up the natural world into its smallest possible commercial parts, rather than improve our ability to work with the biological realm, the result may be further economic and environmental problems for the future. 

American industry and American governmental units have become aware of these problems and of their individual and collective responsibilities in connection with them. No one can doubt for a moment that the aggressive spirit and the technical know-how which have characterized our progress in the past will be more than adequate to solve these problems for the future.3... 

One of the key problems for the future then will be discovering where technology can help and where we need to rely on human judgement. As Bates etal. (2001) point out, human beings are erratic and err in unexpected ways, yet we are also resourceful and inventive and can recover from errors and crises. In comparison, machines, at least most of those currently in use, are dependable but also dependably stupid. An almost perfect instruction, quite good enough for any human operator, can completely disable a machine. Human beings also have the capacity to respond to an unknown unknown , that is an event that could not have been predicted (Bates et a/.,2001). 

How well have laboratories fared in implementing systems in practice From a historical perspective not very well, Betteridge has stated the development of automation in analytical chemistry can be viewed as a series of steps in which the solution of today s bottleneck creates another problem for the future to solve. ... 

There remain some not yet solved problems for the future. One is the polymer matrix itself. For high performance composites epoxy resins on the basis of bisphenol A are used. Some limitations are given by the temperature sensitivity, long curing times, inflammability, limited strain to failure for special high performance qualities and relatively high water absorption. 

Whether they are also formed in living cells remains a problem for the future. An attractive test object for this pursuit is a temperature-sensitive E. coli stringent strain, in which the formation of ppGpp and pppGpp can be observed at 42°C, and its disappearance can be followed by lowering the temperature to the permissive range (below 37 Q. 

Monopnictides form a very interesting ensemble with respect to their magnetic and their transport properties. A large and complex variety of transport phenomena is reported in this category of R and An compounds. The theoretical description of the experimental results is difficult and far frqm complete. There are compounds with extremely low carrier concentrations. Some of them (CeP) can be considered as heavy-fermion systems with a small number of charge carriers. The study of these compounds is certainly one of the most interesting problems for the future. 

The purpose of this article is (a) to describe briefly some of the prokaryotic and eukaryotic systems in current use (b) to indicate where and how such systems have been used to determine biological properties of food additives and food constituents (c) to indicate how such systems can also be used in conjunction with food processing research and development and (d) to speculate on possible research problems for the future. 

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