Microbiological methods literature

Major vitamin Bi2-dependent metabolic processes include the formation of methionine from homocysteine, and the formation of succinyl coenzyme A from methylmalonyl coenzyme A. Thus, apart from directly determining vitamin B12 concentration in serum, elevated levels of both methylmalonic acid and homocysteine may indicate a vitamin B12 deficiency. Serum cobalamine concentration is often determined by automated immunoassays using an intrinsic factor as binding agent. These assays have mainly replaced the microbiological methods. Literature data about vitamin B12 concentration in serum varies. Values <110-150pmoll are considered to reflect deficiency, whereas values >150-200pmoll represents an adequate status. 

Comparison with values from the literature obtained by microbiological methods has been discussed by Stein (S32). The main objection to microbiological methods lies in the fact that amino acid derivatives or combined amino acids may be as readily available to the microorganisms used in these methods as are the parent amino acids from which they... 

The lactones most frequently encountered in literature related to polymerizations are lactide, glycolide and, e-caprolactone the first two being dilactones (Fig 1). Although polymerizations of substituted four-membered ring lactones are also of some importance, the resulting polymers are more conveniently prepared by microbiological methods. 

No doubt the common procedures for analyzing protein hydrolyzates for amino acids despite some notable advances during the last years need improvement. Too much material is required and too much time consumed if more than a few of the most important amino acids are to be determined. There are a number of more or less specific micro methods available, but during the last years attention has been directed to two methods of more general usefulness both for the separation and determination of small quantities of amino acids, namely the adsorption and the microbiological methods. The present review will deal only with the former and does not aim at completeness (which would meet with great difficulties as all literature on the subject is as yet not available to the author) but is intended mainly to emphasize some aspects of the problem which have played a role in the work in the author s laboratory. ... 

Several microbiological procedures for assaying CF have been described in the literature. In general, these methods are designed to measure CF content in a biological fluid or specimen. They all make use of the growth promotion of L. citrovorum 8081, or cere-visiae, as it has been renamed. Before CF was isolated... 

The literature contains very little on methods for biotin determination in foods. Microbiological assays of biotin predominate in food work (19,180). Table 23 summarizes a recent HPLC method for the analysis of biotin in infant formula. 

Much has still to be done in the field of proper use and misuse of CRMs . In this chapter, we will try to translate into understandable analytical language how to use CRMs and particularly matrix CRMs for method validation. It must be stressed that the subject is only rarely discussed in the literature. Therefore, examples will illustrate the principles. Finally, we will also give some advice on the use of CRMs in microbiology. 

The above discussions on the use of CRMs in microbiology could be extended to all types of materials certified for a finite number of cfp and certified through a specific method. Further details on the statistical approach briefly described in the above sections can be found in the literature [12,16]. 

When a pharmacist regularly produces a specific preparation for an individual patient, a better substantiation of the design quality is necessary. Both literature and experimental research may provide extra information about the pharmacotherapy and about pharmaceutical properties such as homogeneity, stability microbiological quality, compatibility, tolerability, and taste. For this, the pharmacist may use data from other pharmacies as well. Furthermore, more specific in-process controls may be added to the preparation process. An end control (usually non-destructive) by the operator is required for every batch, as well as a more specific validation of the preparation method. 

The standard method of analysis for these products is microbiological and gives a rather large deviation between replicates. Several fluorometric and colorimetric procedures have appeared in the literature, but all are time consuming and have only fair accuracy. Nonaqueous titrimetric methods were developed in our laboratory which could be applied successfully to tablets, capsules, ointments, parenterals, and suppositories with an accuracy of about iO.Sfo. Comparative results are shown in Table XVIII. 

The amino acid contents of different preparations of peanut protein (calculated to 16% of nitrogen) are given in Table III. The analyses of the protein isolated by the method of Arthur and others (7,10) were reported by Murphy and Dunn (154). They obtained the values by microbiological assay methods. The analyses of the other preparations were compiled from various literature sources by Guthrie and others (92,100). 

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