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At least 19 recordsLinked to original sources
PubMed1990

Time-related changes in the diagnostic utility of total lactate dehydrogenase, lactate dehydrogenase isoenzyme-1, and two lactate dehydrogenase isoenzyme-1 ratios in serum after myocardial infarction.

Using receiver-operating characteristic (ROC) curve and likelihood ratio analysis, we examined the diagnostic utility of total lactate dehydrogenase (LD; EC 1.1.1.27) activity (I). LD isoenzyme-1 activity (II), and the LD-1 percentage of total LD activity (III), LD-1 LD-2 (IV), and LD-1/LD-4 (V) in 347 persons admitted to the Cardiac Care Unit (of whom 173 were subsequently proven to have had myocardial infarction). Blood was sampled from these subjects at about 6-h intervals for up to 96 h from the onset of chest pain. Defining an "effective" test as one having an area under the ROC curve of greater than or equal to 0.9, we determined the ranked utility (greatest to least) of these tests as V = IV greater than III greater than II greater than I. Tests III, IV, and V had by this criterion, diagnostic effectiveness equivalent to measurements of creatine kinase-2 in serum but in samples obtained at later time intervals. The decision thresholds for both high (constant) test sensitivity and specificity varied with time, to differing extents, over the entire 96-h period, a finding with important diagnostic implications. We document positive and negative likelihood ratio values for each of these tests throughout the entire period of study.

Adult↗
PubMed1976

The maximum activities of hexokinase, phosphorylase, phosphofructokinase, glycerol phosphate dehydrogenases, lactate dehydrogenase, octopine dehydrogenase, phosphoenolpyruvate carboxykinase, nucleoside diphosphatekinase, glutamate-oxaloacetate transaminase and arginine kinase in relation to carbohydrate utilization in muscles from marine invertebrates.

Comparison of the activities of hexokinase, phosphorylase and phosphofructokinase in muscles from marine invertebrates indicates that they can be divided into three groups. First, the activities of the three enzymes are low in coelenterate muscles, catch muscles of molluscs and muscles of echinoderms; this indicates a low rate of carbohydrate (and energy) utilization by these muscles. Secondly, high activities of phosphorylase and phosphofructokinase relative to those of hexokinase are found in, for example, lobster abdominal and scallop snap muscles; this indicates that these muscles depend largely on anaerobic degradation of glycogen for energy production. Thirdly, high activities of hexokinase are found in the radular muscles of prosobranch molluscs and the fin muscles of squids; this indicates a high capacity for glucose utilization, which is consistent with the high activities of enzymes of the tricarboxylic acid cycle in these muscles [Alp, Newsholme & Zammit (1976) Biochem. J. 154, 689-700]. 2. The activities of lactate dehydrogenase, octopine dehydrogenase, phosphoenolpyruvate carboxykinase, cytosolic and mitochondrial glycerol 3-phosphate dehydrogenase and glutamate-oxaloacetate transaminase were measured in order to provide a qualitative indication of the importance of different processes for oxidation of glycolytically formed NADH. The muscles are divided into four groups: those that have a high activity of lactate dehydrogenase relative to the activities of phosphofructokinase (e.g. crustacean muscles); those that have high activities of octopine dehydrogenase but low activities of lactate dehydrogenase (e.g. scallop snap muscle); those that have moderate activities of both lactate dehydrogenase and octopine dehydrogenase (radular muscles of prosobranchs), and those that have low activities of both lactate dehydrogenase and octopine dehydrogenase, but which possess activities of phosphoenolpyruvate carboxykinase (oyster adductor muscles). It is suggested that, under anaerobic conditions, muscles of marine invertebrates form lactate and/or octopine or succinate (or similar end product) according to the activities of the enzymes present in the muscles (see above). The muscles investigated possess low activities of cytosolic glycerol 3-phosphate dehydrogenase, which indicates that glycerol phosphate formation is quantitatively unimportant under anaerobic conditions, and low activities of mitochondrial glycerol phosphate dehydrogenase, which indicates that the glycerol phosphate cycle is unimportant in the re-oxidation of glycolytically produced NADH in these muscles under aerobic conditions. Conversely, high activities of glutamate-oxaloacetate transaminase are present in some muscles, which indicates that the malate-aspartate cycle may be important in oxidation of glycolytically produced NADH under aerobic conditions. 3. High activities of nucleoside diphosphate kinase were found in muscles that function for prolonged periods under anaerobic conditions (e.g...

Adenosine Triphosphate↗
PubMed1977

Activity patterns of phosphofructokinase, glyceraldehydephosphate dehydrogenase, lactate dehydrogenase and malate dehydrogenase in microdissected fast and slow fibres from rabbit psoas and soleus muscle.

Methods for standardized determination of phosphofructokinase (PFK), glyceraldehydephosphate dehydrogenase (GAPDH), lactate dehydrogenase (LDH) and malate dehydrogenase (MDH) activities in nanogram samples of microdissected single fibres of rabbit psoas and soleus muscle are described. Fast and slow fibres in soleus muscle show lower absolute activities of these enzymes than the respective fibre types in psoas muscle. Slow fibres represent a more uniform population in the two muscles according to absolute and relative activities of the enzymes investigated. Slow fibres are characterized by high activities of MDH and relatively low activities of glycolytic enzymes. Fast fibres in the soleus muscle represent a population with high activities of MDH and glycolytic enzymes. Fast fibres in psoas muscle represent a heterogeneous population with high activities of glycolytic enzymes and extremely variable activity of MDH. More than 10-fold differences exist in the MDH activities of the extreme types of this fibre population. Differences in the activity levels of MDH in single fast type fibres but also in the activities of glycolytic enzymes between fast and slow fibres are greater than those reported between extreme white and red rabbit muscles.

Animals↗
PubMed1993

[Tear malate dehydrogenase, lactate dehydrogenase, and their isoenzymes in normal Chinese subjects and patients of ocular surface disorders].

Levels of malate dehydrogenase (MDH), lactate dehydrogenase (LDH) and their isoenzymes in tears of normal Chinese subjects and patients with ocular surface disorders were determined. The normal values of tear LDH and MDH were found to be 45.51 +/- 23.00-81.35 +/- 37.84 mumol.s-1/L and 11.00 +/- 5.33-19.50 +/- 9.17 mumol.s-1/L respectively, disregarding sex or eye distinction. The LDH/MDH ratio reflected sensitively the metabolism of corneal and conjunctival epithelium. The MDH isoenzymes comprised MDHs and MDHm, the former accounting for 80.0%-89.1%. The LDH isoenzymes comprised 5 varieties, of which the ratio H/M of subunit H to subunit M was 0.196 +/- 0.02. The changes in LDH isoenzymes were helpful to the differential diagnosis of external eye diseases, and the increase of MDHm reflected sensitively the degree of injury to the corneal epithelium.

Adolescent↗
PubMed1995

Tear malate dehydrogenase, lactate dehydrogenase and their isoenzymes in normal Chinese subjects and patients of ocular surface disorders.

PURPOSE: To determine levels of malate dehydrogenase (MDH), lactate dehydrogenase (LDH) and their isoenzymes in tears of normal Chinese subjects and patients with ocular surface disorders. METHODS: The age range of normal subjects was 10-88, with 136 male and 128 female subjects. 123 patients suffered from ocular surface disorders. Tears were collected from lower fornix on Xinghua filter disc (0.1mm thick, 5mm in diameter). The values of tear MDH and LDH were determined by MONARCH-2000 Analyzer (U. S. A.). Their isoenzymes were separated by acetate cellulose electrophoresis and were determined by Model CDS-200 light densitometer. RESULTS: The normal values of tear LDH and MDH were 45.51 + 23.00-81.35 + 37.84 umol.s-1/L and 11.00 + 5.33-19.50 + 9.17 umol.s-1/L respectively, disregarding sex or eye distriction (P > 0.05). The values of tear LDH and MDH in the group aged 10-19 were significantly lower than in another groups (P < 0.05). 95% normal ranges of tear MDH aged below 19 and above 20 were 3.63-19.90 umol.s-1/L and 4.20-36.64 umol s-1/L. 95% normal ranges of tear LDH aged below 19 and above 20 were 17.69-82.93 umol.s-1/L and 21.47-150.41 umol.s-1/L. The MDH isoenzymes comprised MDHs and MDHm, the former accounting for 80.0-89.1%. The LDH isoenzymes comprised 5 varieties, of which the ratio H/M of subunit H to subunit M was 0.196 + 0.02. Levels of tear LDH,MDH and their isoenzymes in different diseases were various. CONCLUSIONS: Tear LDH/MDH ratio reflected sensitively the metabolism of corneae and conjunctival epithelium. The changes in LDH isoenzymes were helpful to the differential diagnosis of external eye diseases, and the increase of MDHm reflected sensitively the degree of injury to the corneal epithelium.

Adolescent↗
PubMed1992

Comparative study on determination of alpha-hydroxybutyrate dehydrogenase, lactate dehydrogenase isoenzyme LDH-1 by adsorption on DEAE Sephadex A-50 & electrophoresis.

Serum alpha-hydroxybutyrate dehydrogenase (HBDH) and lactate dehydrogenase isoenzyme (LDH-1) levels by two techniques viz., adsorption on DEAE Sephadex A-50 and by electrophoresis were estimated in healthy subjects and patients with testicular tumours. The correlation coefficient between HBDH and LDH-1 by adsorption technique was found to be r = 0.8. HBDH was found to have a value almost twice that of LDH-1 by adsorption and electrophoretic technique and the activity of LDH-1 obtained by two methods and of HBDH in normals and patients with testicular tumours could be converted using a factor of 0.557. The quantitative method used for determination of HBDH is reliable, accurate, simple and rapid and therefore has better value in a clinical setting than electrophoresis and adsorption techniques which are laborious and time consuming.

Chromatography, Ion Exchange↗
PubMed2000

Tumor grade, microvessel density, and activities of malate dehydrogenase, lactate dehydrogenase, and hexokinase in squamous cell carcinoma.

Squamous cell carcinomas were evaluated with respect to tumor differentiation (through use of hematoxylin and eosin stain), microvessel density (through use of CD-34 immunocytochemical stain), and magnitudes of malate dehydrogenase (MDH), hexokinase, and lactate dehydrogenase (LDH) enzyme activities. Direct correlations were found between tumor grade, MDH activity, and microvessel density. Direct correlations were also found between hexokinase activity and MDH activity and microvessel density. Inverse correlations were found between LDH activity and both tumor grade and MDH activity. These results suggest that the high rate of glucose utilization (indicated by hexokinase activity) found in more poorly differentiated tumors has a higher component of aerobic oxidative metabolism (indicated by MDH activity) and a relatively lower contribution from anaerobic metabolism (indicated by LDH activity) than do the rates found in more differentiated tumors. It is also suggested that as the glycolytic rate increases, more pyruvate goes into the Krebs cycle than into lactate. The availability of glucose-derived pyruvate for oxidative metabolism would mean less of a dependency on glutamine as a carbon source in squamous cell carcinoma.

Carcinoma, Squamous Cell↗
PubMed1982

Glycerolphosphate dehydrogenase, glucose-6-phosphate dehydrogenase, lactate dehydrogenase and carbonic anhydrase activities in oligodendrocytes and myelin: comparisons between species and CNS regions.

Oligodendrocytes isolated from bovine white matter had higher specific activities of glycerolphosphate dehydrogenase (GPDH) and glucose-6-phosphate dehydrogenase (G6PDH) than were observed in homogenates of white matter or gray matter from bovine brains, whereas the activity of lactate dehydrogenase (LDH) was lower in the cells than in the homogenates. These observations suggest that G6PDH, as well as GPDH, is an oligodendrocyte-enriched enzyme. The 3 enzymes were also measured in myelin from bovine brains, rat spinal cords, and mouse brains, and, for each enzyme, the relative specific activity (RSA) in myelin was calculated by dividing the specific activity in myelin by the specific activity in the respective starting homogenate. Of the 3 enzymes, GPDH, G6PDH and LDH, the RSA of G6PDH was highest, at 0.26, in the bovine myelin, whereas the RSAs of GPDH were highest, at approximately 0.20, in the myelin from rat spinal cords and mouse brains. Carbonic anhydrase was also measured in the myelin from the rodent tissues, and significantly higher RSAs, at 0.43-1.06, were obtained. The finding that carbonic anhydrase consistently has higher concentrations than either G6PDH or GPDH in myelin suggests that the latter are restricted, in the myelin sheath, to regions in which oligodendroglial cytoplasm is enclosed, whereas carbonic anhydrase is distributed more broadly in the myelin membranes. A developmental increase in GPDH in the rat spinal cord is also reported.

Aging↗
PubMedDate not supplied

[Effect of insulin and insulin deficiency on the activity of hexokinase, malate dehydrogenase, lactate dehydrogenase and its isoenzyme composition in the smooth muscle of the rabbit stomach].

Decrease in the activity of hexokinase was found in soluble fraction of stomach smooth muscles of rabbits with alloxane diabetes. Administration of insulin into intact rabbits led to distinct decrease in the activity of lactate and malate dehydrogenases in cells of the stomach fundal part. In smooth muscles of rabbits with alloxane diabetes pyruvate was formed from lactate at a higher rate (increase in content of LDH1 and LDH2) and after administration of insulin into the animals--lactate was formed from pyruvate at an increased rate.

Animals↗
PubMed1976

Correlation analysis of Baker's studies on enzyme inhibition. 2. Chymotrypsin, trypsin, thymidine phosphorylase, uridine phosphorylase, thymidylate synthetase, cytosine nucleoside deaminase, dihydrofolate reductase, malate dehydrogenase, glutamate dehydrogenase, lactate dehydrogenase, and glyceraldehyde-phosphate dehydrogenase.

The inhibitory activity of 1058 inhibitors of the title enzymes has been formulated in 13 equations correlating chemical structure with inhibitory potency. Two types of regions in enzymes have been defined by means of pi and molar refractivity constants. The use of indicator variables has been extensively developed to suggest special enzyme-ligand interactions. Several examples are given of the use of correlation equations in comparing structural features of different systems.

Animals↗