Lactate dehydrogenase assay

Standjord, P. E., and Clayson, K. J., The control of inhibitory impurities in reduced nicotinamide adenine dinucleotide in lactate dehydrogenase assays. J. Lab. Clin. Med. 67, 144 (1966). 

The MTT ]3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] and LDH (lactate dehydrogenase) assays are commonly used to evaluate the cytotoxidty of nanomaterials, while measurements of ROS, glutathione (GSH) and hOggl are used to evaluate nanomaterial-induced oxidative stress. The different cell Unes... 

Assay of plasma enzymes aids diagnosis and prognosis. For example, a myocardial infarction elevates serum levels of lactate dehydrogenase isozyme I,. 

Rosalki, S. B. Standardization of isoenzyme assays with special reference to lactate dehydrogenase isoenzyme electrophoresis. Clin. Biochem. (1974), 2> 29-40. 

Part—I has three chapters that exclusively deal with General Aspects of pharmaceutical analysis. Chapter 1 focuses on the pharmaceutical chemicals and their respective purity and management. Critical information with regard to description of the finished product, sampling procedures, bioavailability, identification tests, physical constants and miscellaneous characteristics, such as ash values, loss on drying, clarity and color of solution, specific tests, limit tests of metallic and non-metallic impurities, limits of moisture content, volatile and non-volatile matter and lastly residue on ignition have also been dealt with. Each section provides adequate procedural details supported by ample typical examples from the Official Compendia. Chapter 2 embraces the theory and technique of quantitative analysis with specific emphasis on volumetric analysis, volumetric apparatus, their specifications, standardization and utility. It also includes biomedical analytical chemistry, colorimetric assays, theory and assay of biochemicals, such as urea, bilirubin, cholesterol and enzymatic assays, such as alkaline phosphatase, lactate dehydrogenase, salient features of radioimmunoassay and automated methods of chemical analysis. Chapter 3 provides special emphasis on errors in pharmaceutical analysis and their statistical validation. The first aspect is related to errors in pharmaceutical analysis and embodies classification of errors, accuracy, precision and makes... 

Figure 8.2 The effect of pH on the enzyme lactate dehydrogenase (EC 1.1.1.27). The enzyme shows maximum activity at pH 7.4 (A). When stored in buffer solutions with differing pH values for 1 h before re-assaying at pH 7.4, it shows complete recovery of activity from pH values between 5 and 9 but permanent inactivation outside these limits (B).

L-Amino acid oxidase has been used to measure L-phenylalanine and involves the addition of a sodium arsenate-borate buffer, which promotes the conversion of the oxidation product, phenylpyruvic acid, to its enol form, which then forms a borate complex having an absorption maximum at 308 nm. Tyrosine and tryptophan react similarly but their enol-borate complexes have different absorption maxima at 330 and 350 nm respectively. Thus by taking absorbance readings at these wavelengths the specificity of the assay is improved. The assay for L-alanine may also be made almost completely specific by converting the L-pyruvate formed in the oxidation reaction to L-lactate by the addition of lactate dehydrogenase (EC 1.1.1.27) and monitoring the oxidation of NADH at 340 nm. 

Assays are frequently needed to detect marked and acute cytotoxicity that may confound the interpretation of cell-based efficacy assays. Neutral red uptake is one of the most commonly used cytotoxicity assays and is used in the regulatory phototoxicity assay on NT3 fibroblasts [13]. It has been show to be more sensitive than assays for mitochondrial reductive capacity such as the tetrazolium reductase assays, ATP depletion assays, or for cell permeabilization or mpture such as dye uptake or lactate dehydrogenase leakage. Lysosomes take up, protonate and trap neutral red when cellular ATP production is sufficient to maintain pH gradients. 

Lactate may be quantified spectrophotometrically after reaction with FeCl2, or by an enzymatic assay (using lactate dehydrogenase which can quantify both D- and L-isomers) or by HPLC. 

Measurement of Alanine Aminotransferase Activity The activity (reaction rate) of alanine aminotransferase is usually measured by including an excess of pure lactate dehydrogenase and NADH in the reaction system. The rate of alanine disappearance is equal to the rate of NADH disappearance measured spectrophotometrically. Explain how this assay works. 

It is not surprising that the pyruvic acid intermediate seemed plausible because in a paper earlier in that same year (23), the authors described a malic enzyme from pigeon liver. This enzyme was shown to form appreciable amounts of pyruvic acid from malic acid, but it was NADP instead of NAD specific. The end product was shown to be pyruvic acid by spectrophotometric assay involving lactate dehydrogenase. 

Generally, low molecular mass permeation enhancers can be divided into transcellular and paracellular permeation enhancers. On the one hand the potential of permeation enhancers to open the paracellular route of uptake can be determined by the reduction in the transepithelial electrical resistance (TEER) (enhancement potential = EP). On the other hand the potential of permeation enhancers to open the transcellular route of uptake can be determined by the lactate dehydrogenase (LDH) assay (LDH potential = LP). The parameter K = (EP—LP)/EP represents the relative contribution of the paracellular pathway. Consequently, a K value of 0 means predominantly transcellular and a K value of 1 means predominantly paracellular. Based on this classification system Whitehead and Mitragotri classified over 50 low molecular mass permeation enhancers showing that most of them are paracellular and only a few of them are transcellular permeation enhancers (2008). 

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