Increased alpha-hydroxybutyrate dehydrogenase in serum from children with measles.

For treatment and prognostic evaluation of patients with measles, it is important to determine the source of the increase in serum alpha-hydroxybutyrate dehydrogenase (HBD; EC 1.1.99.6). Here we measured HBD and L-lactate dehydrogenase (LD; 1.1.1.27) activities in the serum of 18 children with measles and in 18 age-matched control patients with bronchopneumonia. HBD and LD activities in the measles patients were significantly higher than those in control subjects (P less than 0.001). The HBD/LD ratio in the measles patients two to three days after the onset of rash was significantly lower than that in control subjects (P less than 0.001). The low HBD/LD ratio was similar to the ratio found in lymphocytes. The number of peripheral lymphocytes decreased markedly after the onset of rash. Our results suggest that increased serum HBD and LD activity is common in measles infection and that the increase originates from the destruction of infected lymphocytes rather than from myocardiac injury.     

Reversible loss of lactate dehydrogenase isoenzymes and lactate dehydrogenase activity in patient's serum

An abnormal lactate dehydrogenase (LD; EC 1.1.1.27) electrophoretogram (only one band, at the application site) and a low LD activity (7 U/L) was seen for a patient's serum during storage at 22 and 4 degrees C. Both reverted to normal when the serum was incubated at 37 degrees C.     

Increased activities of cytosol aminopeptidase and lactate dehydrogenase in serum originate from lymphocytes in necrotizing lymphadenitis

In three pediatric patients with necrotizing lymphadenitis, cytosol aminopeptidase activity (c-AP; EC 3.4.11.1) in serum was markedly increased to 509, 417, and 191 U/L, respectively (normal range 25-60 U/L). Lactate dehydrogenase (LD; EC 1.1.1.27) was also increased, with LD-3 predominating. The increased concentrations of c-AP and LD presumably originated from the destruction of infected, activated lymphocytes, especially T lymphocytes. Necrotizing lymphadenitis is probably caused by a lymphocytotropic virus.     

Increased lactate dehydrogenase isoenzyme 1 in serum and tumor tissue of a patient with small-cell carcinoma

Histological examination of supraclavicular lymph node tissue obtained at biopsy from a 63-year-old man disclosed metastatic small-cell carcinoma. On admission and for four days subsequently, total lactate dehydrogenase (LD; EC 1.1.1.27) activity in serum was 6.5 times normal; studies of LD isoenzyme showed persistently increased LD-1, with LD-1 greater than LD-2. Isoenzyme electrophoresis of tissue homogenates prepared from the patient's tumor also showed the LD-1 greater than LD-2 pattern. Isoenzyme studies for supraclavicular lymph node tissue from five control subjects showed contrasting isoenzyme patterns as compared with the patients in whom LD-2, LD-3, and LD-4 predominated. Because these abnormalities were persistent, they differ from the temporal sequence for LD usually seen in myocardial infarction. This emphasizes the importance of repetitive sampling for clinical interpretation of data on this enzyme.     

A colorimetric assay for serum lactate dehydrogenase

A simple, rapid, colorimetric assay for serum lactate dehydrogenase is described. The method requires 0.05 ml serum and a 12-min incubation at 37° and utilizes a tetrazolium salt in conjunction with a stable intermediate electron carrier (Meldola Blue). Good correlation between the colorimetric assay and a reference spectrophotometric assay was observed.     

Macro lactate dehydrogenase: an LDH-immunoglobulin M complex that inhibits lactate dehydrogenase activity in a patient's serum

A macro lactate dehydrogenase (LDH, EC 1.1.1.27) isoenzyme with a low total LDH activity was present in the serum of a 57-year-old woman with a drug eruption (cutaneous lesions from an allergic reaction to drug administration). The patient's LDH was shown by immunoelectrophoresis to be bound to immunoglobulin G (IgG) and M (IgM). It was found that the patient's IgM acted as an inhibitor of LDH that was specific for the M subunit. When IgM was treated with 0.1 mol/l of 2-mercaptoethanol (2-ME), the inhibiting effect of the IgM to LDH activity disappeared, while treated IgM continued to bind to the LDH molecule. The LDH activity increased approximately two-fold when the patient's serum was treated with 2-ME. LDH activity in normal human serum was inhibited and an abnormal pattern of LDH isoenzyme appeared when the patient's IgM was added to normal serum. The present case seems to be the first report of LDH-IgM complex with a marked decrease of LDH activity.     

Increased serum lactate dehydrogenase isoenzyme 1 and macro creatine kinase type 2 in a patient with lung cancer

A 72-yr-old man, having a lung tumor with metastatic spread to liver and bone, was hospitalized with a lactate dehydrogenase (LD; EC 1.1.1.27) activity and a creatine kinase (CK; EC 2.7.3.2) activity in serum of 30 and 2 times the upper reference limit (URL), respectively. The LD isoenzyme-1/LD activity ratio was 62% (2 times URL). This ratio was maintained throughout hospitalization, during which LD activity increased up to 90 times URL. Macro CK type 2 activity represented almost all of the CK activity, which increased up to 4 times URL during hospitalization. The patient died the 29th day after admission. The enzyme abnormalities were thought to stem from tumor tissue.     

Automated kinetic determination of lactate dehydrogenase isoenzymes in serum.

A steady-state kinetic method has been revised for measuring lactate dehydrogenase isoenzyme activities, which relates the inhibition of heart-type isoenzyme activity to the overall isoenzyme composition of the enzyme subunits. The method depends on the pH-dependent formation of an inhibitory ternary complex by the heart-type isoenzyme with NAD+ and pyruvate (if the reaction is measured by NADH oxidation). A preincubation step in the previous method is eliminated. The isoenzymes are measured by measuring the reduction of pyruvate in two different concentrations, which favor either the total or fractional activity, depending on the concentrations of pyruvate and the percentage of heart-type subunits. The method has been adapted to a centrifugal analyzer, which has speeded automated isoenzyme determinations, with an accuracy comparable to that for electrophoretic methods.     

Complexes of lactate dehydrogenase and immunoglobulin G in human serum

Three patients with electrophoretically abnormal serum lactate dehydrogenase (LDH) isoenzyme patterns due to the presence of LDH-IgG complexes are described. It was found that normal LDH isoenzymes had been complexed with an anomalous immun oglobulin. Concerning the relation of the anomaly with a clinical disorder no definite conclusions could be drawn, although there are some indications that a relation exists between the occurrence of the LDH-IgG complexes and an autoimmune disease.     

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.     

毛细管电泳法分离血清中乳酸脱氢酶同工酶

目的利用还原型辅酶I（NADH）在340nm波长处特异性吸收峰，建立用毛细管区带电泳在线检测人血清中乳酸脱氢酶（LDH）同工酶的方法。方法实验中采用未涂层毛细管，长60cm，内径75μm，pH9．4（23℃）二氨基二甲基1，3丙二醇（AM2P）缓冲液含20mmol/L氧化型辅酶I（NAD^＋）、51，6mmol/L乳酸锂。结果在25min内完成电泳分离，乳酸脱氢酶同工酶1（LDH1）、乳酸脱氢酶同工酶5（LDH5）纯品各自均可得到较好峰形，而且LDH1、LDH2纯品的混合物亦可得到完全分离，在分析正常人血清与肝癌患者血清时，其结果与美国Helena公司REP全自动琼脂糖电泳结果一致，取得满意效果。结论该法快速、低耗，具有较好的推广应用价值。     

A transient variant of serum lactate dehydrogenase isoenzymes.

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.     

Normal values at 37 degrees for serum lactate dehydrogenase, alpha-hydroxybutyrate dehydrogenase and glycerate dehydrogenase

The distribution of serum lactate dehydrogenase and α-hydroxybutyrate dehydrogenase activity in a sample population of 280 volunteers is presented. Enzyme activity was measured at 37° using optimal concentrations of substrate, coenzyme and phosphate buffer. Significant increases in lactate dehydrogenase activity using the substrates pyruvate, 2-oxobutyrate and hydroxypyruvate were found with increasing age. No significant differences between males and females were found with pyruvate as substrate, but were found when 2-oxobutyrate and hydroxypyruvate were used.