An abnormal macro lactate dehydrogenase isoenzyme not due to immunologlobulin binding

We report here on the lactate dehydrogenase (LD) of a patient who presented with an additional LD isoenzyme band between LD 3 and LD4 found during routine examination. The abnormal LD was found to be of increased molecular size, which was not due to complexing with immunoglobulins. The abnormal LD was purified by affinity chromatography, labelled and electrophoresed on a SDS-polyacrylamide gel. Autoradiography suggested abnormal aggregation as the cause of increased molecular size.     

Use of purified lyophilized human lactate dehydrogenase isoenzyme 5 in a study of measuring lactate dehydrogenase activity

We examined the stability of human lactate dehydrogenase (EC 1.1.1.27) isoenzyme 5--purified to a specific activity of about 400 kU/g--when lyophilized in a buffered, stabilized matrix of bovine albumin. This isoenzyme was prepared with a final activity of about 500 U/L and stored at -20, 4, 20, 37, and 56 degrees C for as long as six months. This isoenzyme decayed with approximate first-order kinetics, with an estimated half-life at -20 degrees C of about 475 years. Stability of reconstituted samples stored at 20 or 4 degrees C was poor, suggesting that the reconstituted material should be used without delay; material stored at -20 degrees C showed excellent stability for 15 days. We propose that such preparations might be further investigated as standards for use in electrophoresis of lactate dehydrogenase isoenzymes.     

乳酸脱氢酶同工酶第6条带检测的临床研究

在临床工作中应用改良乳酸脱氢酶(LDH)同工酶试剂盒,检测到乳酸脱氢酶同工酶6(LDH6)条带,对出现LDH6的患者进行追踪检测,发现患者血清LDH总活性都很高,均大于520U/L。同时,当血清LDH6所占总活性比例大于7.9%时,患者2周内即死亡。因此,我们通过改良LDH同工酶试剂检测LDH6酶。可尽快检测出患者肝损伤程度,使其及时得到治疗。     

Abnormal lactate dehydrogenase isoenzyme pattern in a critically ill patient

We have described a patient who had an abnormal isoenzyme of lactate dehydrogenase in both serum and tissue. The presence of LD6 is indicative of a poor prognosis. Some of the biochemical characteristics of the isoenzyme are (1) LD6 is not an artifact, (2) it contains an M subunit but not an H subunit, and (3) it is not an immunoglobulin complex. We believe LD6 may arise during episodes of severe shock as lysosomes rupture and is either a previously sequestered lysosomal LD or is a lysosomal modification of LD5.     

Quantitation of lactate dehydrogenase isoenzyme patterns of the developing human fetus

The differentiation of heart and liver lactate dehydrogenase isoenzymes during embryological development of the human was studied. At the end of 3 mth the percent level of heart monomer in heart and liver were identical. However with further development heart monomers decreased in liver and increased in the heart. The greatest rate of change occurred during the last trimester (7–9 mth) of development, whereby at this time patterns similar to those demonstrable in corresponding adult organs were evident. A similar study involving stillborns suggests the possibility that some of these cases might result from the lack of differentiation of LDH isoenzymes rich in heart monomer.     

Variant expression of lactate dehydrogenase complexes, interfering with isoenzyme analysis

Three patients with an elevated serum LD activity and unusual, but quite different LD isoenzyme patterns, were studied. It was shown by immunofixation procedures, that complexes between LD isoenzymes and immunoglobulins of the IgG-kappa, IgA-kappa and IgG-lambda class, respectively, caused the observed isoenzyme patterns. From mixing experiments it appeared that the immunoglobulins were specific for either the H-subunit only or an antigenic determinant expressed by a combination of H- and M-subunits in the LD isoenzymes. The observed complexes could be dissociated, in vitro, with NAD+ in two patients, while in the third patient the complex was resistant to NAD+ addition. No common denominator was found with respect to clinical diagnosis. Auto-immune disorders or infection with hepatitis B virus were not involved.     

Radial immunodiffusion and immunoelectrophoresis compared for identifying autoantibodies to lactate dehydrogenase in human serum

Variant electrophoretic patterns of lactate dehydrogenase isoenzymes were studied. By radial immunodiffusion and immunoelectrophoresis, immunoglobulin and light chain class of autoantibodies to lactate dehydrogenase were identified in nine sera: seven of these sera demonstrated IgG (5 lambda, 2 kappa) autoantibodies to lactate dehydrogenase, the other two demonstrated IgA (both kappa) autoantibodies to lactate dehydrogenase, the other two demonstrated IgA (both kappa) autoantibodies to lactate dehydrogenase. We conclude that radial immunodiffusion and immunoelectrophoresis are equally effective for identifying auto-antibodies to lactate dehydrogenase in serum. Radial immunodiffusion, however, is easier to perform than immunoelectrophoresis.     

Clinical evaluation of an automated chemical inhibition assay for lactate dehydrogenase isoenzyme 1

We evaluated an automated assay for lactate dehydrogenase (LD; EC 1.1.1.27) isoenzymes, supplied by Boehringer Mannheim Diagnostics (BMD) and based on selective chemical inhibition of non-LD-1 isoenzymes by guanidine thiocyanate. Results were compared with the Roche Isomune LD-1 method. The Hitachi 717 analyzer was used to measure enzyme activity for both procedures in 229 serum samples. One hundred specimens were also analyzed by the Helena rapid electrophoresis (REP) method. We determined the limit of linearity of the BMD method to be about 1200 U of LD-1 per liter. The analytical correlation of BMD (y) with Isomune (x) yielded y = 1.0x + 0.5 U/L, r = 0.997, Sy/x = 16.9 (range 20-1397 U/L). The regression equation for BMD vs REP was y = 1.1x + 7.2% (r = 0.800, Sy/x = 7.4, range 14-83%). Average values for within-run precision for low (38 U/L), medium (180 U/L), and high (865 U/L) controls were 4.1%, 1.0%, and 0.5%, respectively (16 trials of six each). The average values for run-to-run precision were 4.1%, 1.7%, and 1.1%, respectively, for these controls (n = 16). We used receiver-operating characteristic curves to determine optimum decision limits. Using an LD-1 cutoff of 40% of total LD, we obtained a clinical sensitivity of 97-100% and a specificity of 95% when blood was collected during the optimum interval, 24-48 h after the onset of chest pain. We conclude that the BMD LD-1 assay is equivalent to the immunochemical and electrophoretic assays for measuring the LD-1 isoenzyme.     

Serum isoenzyme pattern of creatine kinase and lactate dehydrogenase in various animal species

The creatine kinase and lactate dehydrogenase isoenzyme pattern were determined in the serum of normal and untreated rats, rabbits, dogs, monkeys and pigs. The relative distribution of all isoenzymes in the serum and an electrophoretic pattern for each animal species are presented. The isoenzyme serum pattern showed a great variation between the species. The diagnostic value of serum creatine kinase isoenzyme MB and lactate dehydrogenase isoenzymes 1 and 2 in predicting cardiac lesions in different animal species is briefly discussed.     

A systematic review of lactate dehydrogenase isoenzyme 1 and germ cell tumors.

OBJECTIVES: To evaluate lactate dehydrogenase isoenzyme 1 (LD-1) as a tumor marker of germ cell tumors. METHODS: A literature search included a CancerLit and Medline computer search of articles regarding germ cell tumors and LD-1 published between 1963 to 99 and a manual search of reference lists, theses, and textbooks. Forty articles, letters to the editor, and abstracts on testicular germ cell tumors and 10 articles on ovarian germ cell tumors fulfilled inclusion criteria. RESULTS: Of 696 patients with testicular germ cell tumors, 423 (61%) had a raised serum LD-1 catalytic concentration (S-LD-1). Patients with seminoma have a raised S-LD-1 more often (63%) than those with nonseminoma (60%). S-LD-1 was raised less often in patients with stage I (48%) than in those with stage II (50%) and stage III (67%). S-LD-1, serum alpha fetoprotein concentration (S-AFP), and serum human chorionic gonadotropin concentration (S-hCG) were discordant. S-LD-1 predicted outcome in four studies: one study regarding relapse in patients with nonseminomatous testicular germ cell tumors stage I, and three studies regarding survival of patients with metastatic testicular germ cell tumors. In two of three studies, S-LD-1 was a better prognostic predictor for patients with metastatic testicular germ cell tumors than S-LD. Of 40 patients with ovarian germ cell tumors, thirty-five (88%) had a raised S-LD-1. CONCLUSIONS: S-LD-1 is a useful serum tumor marker of testicular germ cell tumors. For patients with ovarian germ cell tumors, S-LD-1 was raised more often than for patients with testicular germ cell tumors. Further studies are required for a general recommendation regarding the use of S-LD-1 for germ cell tumors.     

Alterations in lactate dehydrogenase isoenzyme patterns after therapy with streptokinase or streptococcal infection

Serum samples from patients receiving intravenous streptokinase were examined for evidence of interaction in vivo between streptokinase and lactate dehydrogenase (EC 1.1.1.27; LD). We found that this treatment produced a band of LD activity that remained at the electrophoretic origin of LD isoenzyme analysis. Treatment with tissue plasminogen activator produced no such band. The streptokinase-LD complex could be removed from serum by ultracentrifugation. It remained in the circulation for as long as 48 h after streptokinase infusion. A similar phenomenon was observed in a case of pneumococcal sepsis. Examination of supernates from both cultures of several species of Gram-positive cocci revealed interactions between human LD and Streptococcus groups A and C and also Streptococcus pneumoniae. Evidently streptokinase can form complexes with LD in vivo after either streptokinase therapy or infection, with consequent alteration of the LD isoenzyme pattern.     

The quality control of serum lactate dehydrogenase isoenzyme separations using commercial quality control sera

The lactate dehydrogenase (l-lactate:NAD oxidoreductase, EC 1.1. 1.27; LDH) isoenzyme content of 31 commercially available quality control sera was determined using thin layer agarose and fluorimetry. Only one of these sera was specifically intended for isoenzyme quality control purposes. The group of human sera, with no additives, proved to be the only one having an LDH isoenzyme distribution suitable for quality control use. Within-batch and between-batch precision has been determined over a 2–3 month period for LDH isoenzyme separations using several human quality control sera. The control of quality of this procedure has been shown to be feasible.