SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Polyethylene glycol (PEG) stabilizes lactate dehydrogenase (LDH) from pig muscle. Time of half-inactivation by the heating at 45 degrees C is linearly increased by PEG from 21.6 min up to 114 min without and at 15% PEG presence, respectively. PEG practically does not affect Michaelis constant and Hill coefficient fro pyruvate and decreases the maximal activity. Possible mechanisms of LDH stabilization by PEG is discussed.
BACKGROUND: Allograft coronary artery disease (CAD) is a major long-term complication in heart transplanted patients. However, the metabolic basis of allograft CAD remains to be fully elucidated. We analyzed the lactate dehydrogenase heart (H) and muscle (M) isoenzyme pattern in endomyocardial biopsy specimens and the evolution of the H/M ratio to test whether changes in this ratio could be the earliest manifestation of allograft CAD. METHODS: Twenty-four heart transplant recipients were followed up for 12 months. Endomyocardial biopsy was performed at 1, 2, 3, 6, and 12 months after transplantation. Lactate dehydrogenase 1 through 5 isoenzymes were separated by electrophoresis, and the H/M ratio was calculated. Two groups of patients were identified: group 1 (n = 20), patients without allograft CAD; and group 2 (n = 4), patients with poor outcome (three deaths, 1 case of low cardiac output) and angiographic and histologic evidence of allograft CAD. RESULTS: Both groups had similar H/M baseline values. The H/M ratio was higher (p = 0.01) in group 1 at 6 months (3.48 +/- 0.64 versus 2.17 +/- 0.43) and 12 months (3.76 +/- 0.92 versus 2.18 +/- 0.45) when compared with group 2. The H/M ratio increased from 2.78 +/- 0.89 at 1 month to 3.76 +/- 0.92 at 12 months (p = 0.02) in group 1 and decreased in group 2 (2.86 +/- 0.49 versus 2.18 +/- 0.45; not significant). CONCLUSIONS: Changes in H/M ratio reflect an anaerobic shift in the lactate dehydrogenase isoenzyme composition and can be taken as an early indicator of allograft CAD.
An unusual variant of the serum lactate dehydrogenase (LDH) isoenzyme pattern is described in an apparently healthy young woman. The abnormal pattern consisted of a single zone of LDH activity, having the same mobility as, but more diffuse than, normal LDH-4. The molecular weight of the abnormal LDH complex is approximately 280 000, but the nature of the additional component remains unknown, as the isoenzyme pattern spontaneously reverted to normal six weeks after it was first noticed.
A hitherto unreported lactate dehydrogenase isoenzyme, which migrates electrophoretically to the relative position between LDH4 and LDH5, is detected in 100% of human saliva specimens obtained from a group of apparently healthy individuals. Despite the fact that 70% (14 of 20) of all specimens analyzed have LDH5 as the predominant isoenzyme, it has been observed that this newly discovered isoenzyme has anomalously emerged as the predominant isoenzyme in 20% (4 of 20) of the total specimens quantified.
Higher eukaryotes contain tRNA transglycosylases that incorporate the guanine derivative queuine from the nutritional environment into specific tRNAs by exchange with guanine at position 34. Alterations in the queuosine content of specific tRNAs are suggested to be involved in regulatory mechanisms of major routes of metabolism during differentiation. Dictyostelium discoideum has been applied as a model to investigate the function of queuine or queuine-containing tRNAs. Axenic strains are supplied with queuine by peptone, but they grow equally well in a defined queuine-free medium. Queuine-lacking amoebae, starved in suspension culture for 24 h, lose their ability to differentiate into stalk cells and spores, whereas amoebae sufficiently supplied with queuine will overcome this metabolic stress and undergo further development when plated on agar. The results presented here show that D(-)-lactate occurs in the slime mould in millimolar amounts and that its level is remarkably decreased in queuine-lacking cells after 24 h of starvation in suspension culture. On isoelectric-focusing polyacrylamide gels, nine different forms of NAD-dependent D(-)-lactate dehydrogenase can be separated from extracts of vegetative cells, and six forms from extracts of the starved cells. Under queuine limitation, one form is missing in the starved cells. Low amounts of L(+)-lactate are usually found in vegetative amoebae but significantly less in queuine-lacking cells. Five forms of NAD-dependent L(+)-lactate dehydrogenase are detectable in extracts from vegetative, queuine-treated cells, and slight alterations occur in queuine-deficient amoebae. In the starved cells only one form of L(+)-lactate dehydrogenase is found, irrespective of the supply of queuine to the cells. A cytochrome of type b with an absorption maximum at 559 nm accumulates during starvation only in queuine-lacking cells; it might be a component of an NAD-independent lactic acid oxidoreductase as is cytochrome b 557 in yeast and be responsible for the reduced level of lactate in cells lacking queuine in tRNA.
OBJECTIVE: The aim of this study was to investigate the peritoneal fluid and serum lactate dehydrogenase (LDH) levels in patients with ovarian masses. MATERIALS & METHODS: Peritoneal fluid and serum lactate dehydrogenase (LDH) levels were measured in 27 patients with epithelial ovarian carcinoma and 38 with benign ovarian tumors. Serum and peritoneal fluid LDH levels were also compared with the levels of CA-125. RESULTS: Both of the marker levels in ovarian cancer patients were significantly higher than those in patients with benign ovarian tumors. Serous and undifferantiated carcinomas presented higher marker levels than endometrioid and mucinous carcinomas. High grade, advanced stage and positive cytology were associated with higher serum and peritoneal fluid LDH levels; there was an inefficient correlation between them but, when these two markers were used together with CA-125, sensitivity of CA-125 increased to 70%. CONCLUSIONS: In conclusion, serum LDH can be used to discriminate adnexal mass origin and peritoneal fluid LDH may have prognostic value because of the strict relationship with advanced stage, poor histologic type, higher grade and positive abdominal cytology. Peritoneal LDH is found to be a reliable biochemical marker related to prognosis in ovarian carcinoma patients.
Lactate dehydrogenase (LDH) was detected in extracts of untreated and NaOH-treated Mycobacterium leprae. Since armadillo liver LDH isoenzymes with a similar electrophoretic mobility were shown to be considerably more sensitive to inhibition by oxamate than LDH in M. leprae extracts, it was confirmed that M. leprae grown in armadillo liver has its own LDH. Neither the activity of LDH in M. leprae nor its electrophoretic mobility supported the tentative suggestion that an "anomolous" LDH isoenzyme in infected skin biopsies was in fact an M. leprae-derived enzyme.
Cerebrospinal fluid (CSF) lactate dehydrogenase (LDH) was measured in 54 neonates with intracranial hemorrhage and compared with 82 control, 27 traumatic lumbar puncture, seven meningitis, and 30 asphyxiated newborns. Hospital data, neonatal outcomes, and long-term neurodevelopmental follow-up results were reviewed. CSF LDH was not significantly affected by traumatic lumbar puncture but was elevated in proportion to the severity of CNS hemorrhage as scored by computerized tomography. LDH was also significantly associated with subsequent seizures and hydrocephalus and abnormal long-term developmental outcome.
Rats were used to study the general activity and the isoenzyme spectrum of lactate dehydrogenase (LDH) during single-instance and long-term introduction of polychlorocamphene. Total lactate dehydrogenase activity decreases in the liver during the single-instance introduction of half the LD50 (120 mg/kg). The isoenzyme spectrum of LDH is characterized by an increase in the quantity of LDH1, LDH2, and LDH3 and by a decrease in the amount of LDH4. The overall LDH activity does not change in blood serum. The isoform ratio changes insignificantly and LDH1 falls, but normalized 15 days after the introduction of the compound. Long-term introduction of polychlorocamphene at levels 1/100 the LD50 dose over 1.3 and 6 months causes a reduction in the overall LDH activity, both in the liver and in the serum. A decrease in the activity of the basic LDH isoenzyme of the liver (LDH5) and a sharp increase in LDH3 are characteristic for the isoenzyme spectrum of the liver. LDH1 and LDH4 decrease and LDH2 and LDH3 increase in blood serum. Beginning with the third month of polychlorocamphene introduction, LDH1 tends to return to normal levels. LDH2, LDH3, and LDH4 do return to normal levels, while LDH5 increases regularly. This results in a reduction of the number of H subunits and an increase of M subunits. This is characteristic of hypoxic states. On comparing the changes in the LDH enzymes of the liver and blood serum, it can be considered that the introduction of polychlorocamphene does not result in an increase in the permeability of the cellular membranes of the liver for LDH isoenzymes, while the observed isoenzyme spectrum shifts in blood serum are either the result of the biosynthesis of the isoforms of this enzyme changed by the compound or the result of the permeability for them of cells of other tissues.
Threonine 246 in Bacillus stearothermophilus L-lactate dehydrogenase has been changed to valine, serine, and alanine by site-directed mutagenesis. Kinetic analyses show a decrease in substrate inhibition for pyruvate reduction with the T246S mutant and virtual elimination of substrate inhibition for the T246A and T246V mutants. The results indicate that the absence of substrate inhibition in the 246A/V-catalyzed reactions is due to the elimination of a key hydrogen bond between the hydroxyl group of threonine and pyruvate in the wild-type complex that is an important contributor in the formation of the abortive enzyme-NAD(+)-pyruvate complex responsible for substrate inhibition.
We determined lactate dehydrogenase (LD; EC 1.1.1.27) in serum from 75 sequential measles patients and 105 control patients. In the measles patients, LD was increased to 1147.9 +/- 43.8 (mean +/- SE) U/L, markedly more than in the control group (517.2 +/- 15.0 U/L, p less than 0.001). Both LD-3 and LD-4 isoenzymes were increased, but the concentration of LD-5 was normal. Patients with high LD values (greater than 1500 U/L) had longer hospital stays than did those with lower values (p less than 0.01). Our results suggest that increased LD in serum is a common finding in measles infection and presumably originates from lymphocytes.
Two patients with low lactate dehydrogenase (LD) activity were discovered during healthcare examinations and were found to be homozygous for LD-H (heart) subunit deficiency by electrophoretic isoenzyme analysis of serum and erythrocyte hemolysate. The molecular nature of the genetic mutations was characterized by amplification by the polymerase chain reaction and DNA sequencing. In one case, a single-base substitution (T-->G transversion) at codon 147 of the LD-H(B) gene resulted in a nonsense mutation; in the other case, a deletion of 2 base pairs had occurred at codon 139, resulting in a frameshift translation and premature termination.
The dependence of lactate dehydrogenase inhibition at high pyruvate concentrations on pH and neutral salt anions was studied. It was shown that Cl- anions compete with the substrate within the ternary inhibitory complex, ENADpyr in equilibrium ENADCl-, as a result of which the pyruvate-induced inhibition is eliminated. The KD values for Cl- (50 mM) and I- (27 mM) were calculated from the substrate velocity curves at high concentrations of pyruvate. It was supposed that pyruvate inhibition elimination by OH- proceeds via the same kinetic mechanism. The pK value (7.1 +/- 0.1) calculated from this model corresponds to pKn of essential His-195. The additivity of OH- and Cl- function was demonstrated.
Aqueous humor lactate dehydrogenase (LDH) levels were assayed for 23 patients with histologically proved retinoblastoma. The mean aqueous level was 1,886 IU/liter. Twenty-one of these patients had an aqueous humor LDH level above the normal mean. Clinicopathological parameters were determined and evaluated using standard statistical formulas. Only the presence of tumor in the anterior chamber correlated significantly with the aqueous humor LDH level. The following clinical features did not correlate with aqueous humor LDH levels: sex, family history, bilaterality, prior treatment, presentation age, enucleation age, and metastasis. The following pathological features did not correlate with aqueous humor LDH levels: calcification, necrosis, rosettes, inflammation, choroidal or optic nerve invasion, or neovascularization.
Lactate dehydrogenase (LDH) was entrapped in phosphatidylcholine liposomes to evaluate the protective effect of liposomes against protease digestion. Three different preparations of LDH either encapsulated in liposomes, unencapsulated in liposomes or in the absence of liposomes were incubated with the protease trypsin. The loss of LDH activity was measured at intervals over a 12-hour period. The degradation rate of LDH was found to be the same when LDH was unencapsulated in the presence or absence of liposomes. However, when LDH was entrapped in liposomes the degradation rate was 4 to 24 folds slower. This finding indicates that encapsulation of a protein in a liposome protects the protein from the degrading effects of a protease enzyme.
The distribution of placental alkaline phosphatase and lactate dehydrogenase types in 635 placentas from various endogamous groups of Maharashtra have been studied by starch gel electrophoresis. In the case of alkaline phosphatase, 6 common phenotypes and 6 rare phenotypes (F2I1, S1S2, S2S3, I1S2, F1S2, F1I2) are encountered. The highest frequency of Pls1 allele (0.7394) and lowest frequency of Pli1 allele (0.0246) have been found in the Nava-Budha. 6 cases of Cal-1 and 5 cases of Cal-2 types of LDH variants have been observed in the total samples, and Muslims possess the highest frequency of Cal-1 types (3.64%). Population groups are compared with respect to Pl alleles.
Serum lactate dehydrogenase (LDH) levels are elevated in patients with Pneumocystis carinii pneumonia (PCP). In patients receiving aerosolized pentamidine (AP), PCP may be less severe and present with more localized radiographic infiltrates. We evaluated the diagnostic utility of the serum LDH level in 11 patients developing PCP while receiving AP. Serum LDH levels were increased 72.7 +/- 19.0 percent over mean baseline levels and 76.4 +/- 26 percent over the upper limit of normal value for our laboratory with the development of PCP. An elevated serum LDH value remains a useful diagnostic adjunct in the patient developing PCP while receiving AP. Isolated LDH values must be interpreted with caution given the potential for marked variability in the baseline LDH value.
It is known that a part of lactate dehydrogenase in animal tissues is bound to the structural elements. However, if in the tissues of higher animals this part is insignificant, in fish tissues it can make tens of percent. The work is the continuation of a series of experiments on the comparative characteristic of the free and bound glycolytic enzymes in fish tissues, in this case-brain of the sea teleost scorpion fish. It was found that the sensitivity of LDH activity to different pH values and to the inhibition by high pyruvate concentrations were different for the both forms. The enzyme affinity for pyruvate and NADH was 4-6 times lower in free enzyme. Possible physiological significance of bound LDH form existence in the energy supply of the brain is discussed.