Laboratory medicine values

Once the empirical and molecular formulas of the active compounds are determined, then their structural formulas are sought. At that point, synthetic work can begin. The chemist can identify compounds in the material that have medicinal value and find a way to synthesize them, or prepare them in the laboratory, so that they can be made available in large quantities. 

The complete traceability chain as presented here is valid only for those measurable quantities, which can have a value, expressed in SI units. When primary or secondary calibrators are not available the traceability chain for many measurands in laboratory medicine ends at a lower level, e.g. at the manufacturer s standing measurement procedure. In a situation where a manufacturer detects a new diagnostic marker and defines the measurable quantity by establishing a measurement procedure for this marker, the manufacturer s measurement procedure will form the top of the traceability chain. Nevertheless even in this simple situation the principles of the traceability concept are applicable. 

Clinical Chemistry, Laboratory Medicine, and Evidence-Based Laboratory Medicine In this chapter, we review the new influences on clinical chemistry and laboratory medicine from the fields of cfinical epidemiology and evidence-based medicine (EBM). Cfinical epidemiologists have developed study designs to quantify the diagnostic accuracy of the tests developed in laboratory medicine, and study methods to evaluate the effect and value of laboratory testing in healthcare. Practitioners of EBM focus on use of the best available evidence from such well-designed studies in the care of individual patients. EBM rephrases problems in the clinical care of patients as structured clinical questions, looks for the available evidence, evaluates the quality of cfinical studies, evaluates the clinical implications of the results, and provides tools to help clinicians optimally use those results in the care of individual patients. 

Harris EK, Boyd J. Statistical bases of reference values in laboratory medicine. New York Marcel Dekker, 1995 238-50. 

The International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) recommends the term reference values and related terms, such as reference individual, reference limit, reference interval, and observed values. The definitions given below and the presentation in the following sections of this chapter are in accordance with the IFCC recommendations. ... 

Albert A, Heusghem C. Relating observed values to reference values The multivariate approach. In Grasbeck R, Alstrom T, eds. Reference values in laboratory medicine. Chichester, England John Wdey, 1981 289-96. 

Solberg HE. Statistical treatment of reference values in laboratory medicine Testing the goodness-of-fit of an observed distribution to the Gaussian distribution. Scand J Clin Lab Invest 1986 46 (Suppl. 184) 125-32. 

Statland, B.E. and Winkel, P. (1981). Selected pre- analytical sources of variation. In Grasbeck, R. and Ahlstrom, T. (eds.). Reference Values in Laboratory Medicine, John Wiley Sons. 

The realisation that every laboratory determination that is carried out is associated with both random and systematic errors has had a major impact on laboratory medicine in the last thirty years. It is also at the heart of quality control and quality assurance procedures which are primarily concerned with understanding the sources of such errors and their suppression or minimisation (Whitehead, 1977 Aitio, 1981 Taylor, 1987). However, it has been pointed out by Broughton (1983) that all laboratories may carry out some form of "quality control" but this is often designed to give retrospective reassurance rather than provide prospective action. The dual concepts of bias and precision in laboratory medicine are well known, but not always appreciated even by users of reference materials (Taylor. 1985 Taylor, 1987). By definition an unbiased result should be the "true" result, but in practice this is hardly ever achieved. The nearest approach to a true value is generally obtained by using a certified reference material and a definitive method, but these ideals are unobtainable in the case of most trace metal analyses. 

Fraser CG (2004). Inherent biological variation and reference values. Clinical Chemistry and Laboratory Medicine, 42 758-764. 

We must pay attention, however, to the fact that the nature of autopsy materials is quite different from those used in clinical medicine. A blood sample obtained at autopsy is sometimes extremely hemolyzed and its supernatant is neither serum nor plasma, because postmortem intensive fibrinolysis following blood coagulation had already occurred in the corpse at autopsy. Body fluids other than blood/urine or extract of tissue-homogenate cannot normally be considered for clinical use. Most important is that many kinds of proteins are contained in extremely large amounts in autopsy material, which may be available for forensic examination and can by no means be expected to be used in clinical laboratory medicine. Such samples can cause very strong suppression of necessary immunoreactions in the assay system established for clinical use. This means that the values determined may not be comparable if different immunoassay kits are used, even if the same protein is assayed. Besides, the value for a postmortem sample may be false if its assay is completely carried out in a clinical laboratory where no one knows about the particular nature of the autopsy material. This is the probable reason that some conclusions obtained from different studies on the same substance are sometimes contradictory. In spite of such circumstances, the attempted quantitative analysis has been reported as useful in most of the earlier studies. 

In the context of drug discovery, computational methods do not add value unless they can achieve practical results. Results must be produced quickly enough so that they can influence decision making in chemical synthesis. Most importantly, computational methods must be accurate enough to maintain the trust of the medicinal chemist. Without this trust, computational predictions will rarely be tested in the laboratory, which will then prevent the generation of critical data useful for improving the original predictions. 

Table 1,2,3, and 4, normal laboratory values.17 ACP Medicine 2005 available at http //online.statref.com/UserLogin. aspx 6dd=48 docid=2681 Path=/document.aspx Product=StatRef Produc tID=48 accessed November 21, 2005. 

Other naturally derived aflatoxin inhibitors obtained from the "neem" tree have been investigated in our laboratory (84), Azadirachta indica Juss. commonly known as "margosa" or "neem" is an ornamental tree of Asia and Africa that produces natural products having reputed value for their medicinal, antiviral, antibacterial, insecticidal, antifungal and antinematode properties (86, 87). Several active principles from different parts of the neem tree have been reported (88). Our investigation (84) examined the effects of these neem leaf components in neem leaves on aflatoxin biosynthesis by either Aspergillus parasiticus or A. flavus. 

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