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At least 955 records · Page 53Linked to original sources
PubMed1984

Sources of error in determinations of carnitine and acylcarnitine in plasma.

Radioactive and nonradioactive L-carnitine and acyl-L-carnitine were used to evaluate the washing procedures used during the determination of free, total, short-chain, and long-chain acylcarnitine in human and sheep plasma. The volume of fluid trapped by the protein precipitated by perchloric acid is approximately 24% of the total fluid volume and thus contains 24% of free carnitine and short-chain acylcarnitine. Washing twice with distilled water removes about 25% of the long-chain acylcarnitine along with the trapped free carnitine and short-chain acylcarnitines. Washing the pellet twice with a 60 g/L solution of perchloric acid completely removes the trapped free carnitine and short-chain acylcarnitine but does not remove the bound long-chain acylcarnitines. Thus washing with perchloric acid is essential for accurate measurement of long-chain acylcarnitines in plasma samples.

Acetylcarnitine↗
PubMed1984

[Significance, sources of error and limits of protein diagnosis in urine. I. Diagnostic methods].

Determination of proteins in the urine requires standardized collection and storage of urine. To quantify total protein and to separate single proteins electrophoretically unconcentrated urine should be used. Protein dye-binding methods, beta 2-microglobulin essay and polyacrylamide gel techniques can be recommended for routine urinalysis. However, the analytical limits and pitfalls of the methods must be considered. The application of the selectivity concept of proteinuria is restricted to patients with nephrotic syndrome.

Biopsy↗
PubMed1984

[Significance, sources of error and limits of protein diagnosis in urine. II. Normal values and classification of pathologic proteinurias].

Physiological excretion of total protein in the urine of newborns, infants, children and adults is below 150 mg/d/1.73 m2. Albuminuria is below 25 mg/d/1.73 m2 and excretion of beta 2-microglobulin below 0.4 mg/d/1.73 m2. Fever, exercise and orthostasis may cause a reversible increase of protein excretion. The significance of isolated and persistent proteinuria remains obscure. Polyacrylamide gel techniques differentiate between pathological high or low molecular weight proteinuria and thereby glomerular and tubular disorders.

Adult↗
PubMed1980

Platelet adsorption-source of error in reference controls.

Preparation of platelet reference controls requires that the platelet membranes be strengthened by chemical cross-linking, usually with glutaraldehyde. The reaction produces a platelet which is strongly absorbed to plastic and glass surfaces. Tests of commercially available reference controls indicate adsorption to the counting containers. Surfactants inhibit adsorption but cause an apparent decrease in size. Polyethylene glyocol can eliminate adsorption without altering conductivity.

Aldehydes↗
PubMed1980

Monitoring central nervous system methotrexate levels via subcutaneous reservoir. Sources of errors in sampling and their avoidance.

The Ommaya reservoir allows for ready, well-tolerated direct access to the intraventricular cerebrospinal fluid (CSF). The toxicities associated with central nervous system (CNS) methotrexate (MTX) therapy have been attributed to prolonged high levels of the drug. When samples of CSF are removed from a reservoir for the monitoring of MTX levels, there may be sampling errors introduced by retention of high concentrations of drug in the reservoir. Using an in vitro system we confirm this possibility and show that using different injection or sampling techniques will increase or decrease this error. Without proper sampling, particularly several days after the initial injection, one may overestimate the MTX level and may unnecessarily alter treatment. A simple method of avoiding this error is to flush the reservoir after drug injection with a small (3-5 ml) volume of CSF withdrawn prior to injection.

Injections, Spinal↗
PubMed1982

[The 19S(IgM)-FTA-ABS test in the serodiagnosis of syphilis. Technique, sources of error and diagnostical information of results (author's transl)].

This study is based on the results of investigations with the 19S(IgM)-FTA-ABS in serum samples of more than 10,000 patients with treated or untreated syphilis. On the basis of the findings several experiences concerning the technique of the test as well as the possibilities of biological or technical errors are reported. Furthermore, the interpretation of test results is discussed. It is shown that in many cases a differentiation between sufficiently treated and those patients is possible who need specific treatment. Finally the indications for preparing the test are mentioned. It is concluded that at the present time the performance of the 19S(IgM)-FTA-ABS test should be restricted to specialized laboratories.

Antibody Formation↗
PubMed1982

[The methodological and technical sources of error in the performance of the rhinomanometrically controlled intranasal provocation test (author's transl)].

Nasal ventilation can be ascertained with the aid of rhinomanometry. In fact, even a trivial nasal allergic reaction can be detected through the use of the intranasal provocation test, coupled with rhinomanometrics. The different rhinomanometric measurement procedures, including determination of active and passive rhinomanometry, will be discussed in the following article. The advantages and disadvantages of each will be elaborated. The application of the active rhinomanometry however, invites not only certain technical errors but errors of method as well. These will be individually discussed in more detail.

Equipment Failure↗