Determination of Fluorine in Biological Materials: A Review

1994 ◽  
Vol 8 (1) ◽  
pp. 80-86 ◽  
Author(s):  
P. Venkateswarlu
Keyword(s):  
Analytical Methods ◽  
Biological Materials ◽  
Body Fluids ◽  
Future Research ◽  
Final Measurement ◽  
Interpretation Of Results

This review on determination of fluorine in biological materials briefly covers (a) a discussion of various forms of fluorine in body fluids and tissues [and also in foods]; (b) methods of their determination, including pretreatment of samples, separation and concentration of F and its final measurement; (c) an evaluation of the analytical methods used and interpretation of results; and (d) some recommendations for future research in fluorine analytical methods applicable to biological materials.

Lactic Dehydrogenase

1964 ◽  
Vol 10 (8) ◽  
pp. 749-758 ◽  
Author(s):  
Myron S Weinberg ◽  
Daniel H Adler
Keyword(s):  
Analytical Methods ◽  
Lactic Dehydrogenase ◽  
Diagnostic Value ◽  
Body Fluids ◽  
Tissue Necrosis ◽  
Ldh Activity ◽  
Mathematical Correlation ◽  
Serial Samples ◽  
Kinetics Of

Abstract Determination of lactic dehydrogenase (LDH) activity has been shown to have diagnostic value in pathologic states involving tissue necrosis and neoplasia. Necrotizing tissues release this enzyme, which catalyzes the reduction of pyruvate to lactate or the reverse, in an active state. As a result of this release, the enzyme appears in body fluids, notably the blood. Increase of this activity over normal indicates necrosis. The present paper compares the results of the Wroblewski and LaDue and the Wacker et al., methods for measuring LDH activity. Results of the two methods were found to be not comparable. No calculation can be found to relate the results of the two analytical methods. Only 18 of 30 samples gave abnormally high results by both methods. Changes between serial samples drawn on the same patient are not always in the same direction when measured by both methods. Lack of mathematical correlation between the kinetics of the pyruvate-to-lactate reaction and the lactate-to-pyruvate reaction is assumed to explain this.

Methods for determination of labile soil organic matter: An overview

2010 ◽  
Vol 27 (2) ◽  
pp. 49-60 ◽  
Author(s):  
Eduard Strosser
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Analytical Methods ◽  
Wide Spectrum ◽  
Future Research ◽  
Soil Productivity ◽  
Advantages And Disadvantages ◽  
Functional Characterisation ◽  
Labile Soil Organic Matter

Methods for determination of labile soil organic matter: An overviewSoil organic matter (SOM) can be divided into three main pools: labile, stable and inert. Research over recent years has focused on the labile fraction (LF), as it is considered a quickly reactive indicator of soil productivity and health, and important as a supply of energy for soil micro-organisms. A wide spectrum of analytical methods has been used to determine and/or evaluate LF, based on physical, chemical and biochemical principles. The advantages and disadvantages of each technique are explored in this work, but none of the methods can determine LF sufficiently, either because a part of the LF is not involved or because further characterisation is missing. Although analytical methods are widely used to evaluate changes in soil management or organic carbon turnover, the practical question of the quantity and quality of SOM cannot be answered completely. It is also suggested that future research should focus on the interactions among SOM fractions and their better chemical and functional characterisation. It is possible to use a combination of the analytical methods reviewed here in order to accomplish this objective.

Enhanced information from biological materials through technological improvements in cryo-electron microscopy

1992 ◽  
Vol 50 (1) ◽  
pp. 788-789
Author(s):  
Marc J.C. de Jong ◽  
Wim M. Busing ◽  
Max T. Otten
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Biological Materials ◽  
Electron Crystallography ◽  
Cryo Electron Microscopy ◽  
Transmission Electron ◽  
The Many ◽  
Technological Improvements ◽  
Beam Damage

Biological materials damage rapidly in the electron beam, limiting the amount of information that can be obtained in the transmission electron microscope. The discovery that observation at cryo temperatures strongly reduces beam damage (in addition to making it unnecessaiy to use chemical fixatives, dehydration agents and stains, which introduce artefacts) has given an important step forward to preserving the ‘live’ situation and makes it possible to study the relation between function, chemical composition and morphology.Among the many cryo-applications, the most challenging is perhaps the determination of the atomic structure. Henderson and co-workers were able to determine the structure of the purple membrane by electron crystallography, providing an understanding of the membrane's working as a proton pump. As far as understood at present, the main stumbling block in achieving high resolution appears to be a random movement of atoms or molecules in the specimen within a fraction of a second after exposure to the electron beam, which destroys the highest-resolution detail sought.

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