Expression of lactic dehydrogenase isoenzymes in rabbit muscle during development

• 1.1. Rabbit cDNA probes for H and M lactic dehydrogenase subunits were used to monitor mRNA levels in different muscle types during growth.
• 2.2. At the same time, lactic dehydrogenase activity and relative quantities of H and M protein subunits were measured.
• 3.3. The main results are that mRNA abundance depends on muscle type and age, and mRNA abundance is not correlated with enzymatic activity.

     

Electrophoretic and immunofluorescent study of lactate dehydrogenase isoenzymes during eye regeneration in adult tritons]

The spectrum of LDH isozymes was studied at the successive stages of retinal regeneration from the pigment epithelium and lens cells from the iris margin in the adults Pleurodeles waltlii. The combination of two methods, electrophoresis and immunofluorescence, has revealed the slow and rapid LDH isozymes with different intensity of histochemical staining in cells of the tissues under study (pigment epithelium, retina, iris and lens). During the regeneration the spectra of LDH isozymes peculiar to the pigment epithelium and iris and characterized by the predominance of slow forms were substituted by those peculiar to the retina and iris and characterized by the predominance of rapid forms. The rearrangement is realized in the proliferative phase during the transformation of one cell type into another.     

The distribution of lactate dehydrogenase isoenzymes in adult human Achilles tendons

The authors have studied the LDH isoenzymes distribution in the human Achilles tendons. Connection between the age, sex, and enzyme activity were not found. In the Achilles tendon were found strong activity of isoenzymes IV and V (M-type), and controversy them moderate activity of isoenzymes I and II (H-type).     

Lactate dehydrogenase isoenzymes during regeneration of the lens and retina in adult tritons

The range of lactate dehydrogenase (LDG) isozymes has been studied at the consecutive stages of retina regeneration from pigmented epithelium cells and lens regeneration from iris margin in adult crested newts. It was shown that the spectra of LDG isozymes peculiar to pigment epithelium cells and iris and characterized by the predominance of slowly migrating forms are replaced in the lens and retina regenerates by spectra characterized by the predominance of rapidly migrating isozymes which are peculiar to definitive lens and retina.     

Lactate dehydrogenase and its isoenzymes in human umbilical cord tissue]

Study on umbilical cord tissue, completely bloodless, for determination of lactate deshydrogenase activity and its distribution among the five iso-enzymes. Comparison with placenta, amniotic fluid, serums of blood of cord and of mother. Cord tissue is very active (about 360 muKatals, in average) and it is a similar result in placenta (as it is possibly bloodless). Blood serum of cord is more active than amniotic fluid, which is more active than maternal serum, but they are 80 to 200 times less active than cord tissue. After electrophoresis, a very large predominance of the slow iso-enzymes L.D.H. 4--5 is found in cord tissue (72%), amniotic fluid (67%) and placenta (56%), whereas the fast iso-enzymes L.D.H. 1--2 are predominant in the serums of cord blood and of mother. These data indicate an intense metabolic activity in the cord tissue, which has also an high level of lactate, and this seems related to the foetal metabolism for anaerobic glycolysis in oxygen weakly provided tissues.     

Serum lactic dehydrogenase predicts mortality in patients with AIDS and Pneumocystis pneumonia.

Serum lactic dehydrogenase (LDH) activity was compared with mortality in patients with the acquired immunodeficiency syndrome (AIDS) and Pneumocystis carinii pneumonia during the first four days of admission to assess the test''s predictive value. In 30 admissions, 29 patients who survived an episode of Pneumocystis pneumonia had a mean LDH value of 385 IU, with five values greater than 520 IU. Eight with pneumonia who died had a mean value of 926 IU: all had values higher than 520 IU. The mean LDH values for 20 patients with AIDS (35 admissions) who survived and 4 who died of non-Pneumocystis disease were 240 IU and 350 IU, respectively; these patients were the control population. The positive and negative predictive values for survival using 520 IU as the threshold are 61% and 100%. Thus, LDH measurements in the first days of admission for P carinii pneumonia predict mortality and are useful in guiding future management.     

Serum alkaline phosphatase and lactic dehydrogenase activity in cows with retained fetal membranes

Serum alkaline phosphatase (AKP) and lactic dehydrogenase (LDH) activities were determined for 15 cows with retained fetal membranes (RFM) and 15 cows without retained fetal membranes (WRFM). The results revealed that the levels of both AKP and LDH were significantly higher in cows with RFM during late gestation and continued to be higher until 5th day postpartum. The usefulness of these findings for the prediction of RFM before parturition and for evaluating the therapeutic response of RFM is discussed.     

Additional lactate dehydrogenase (LDH) isoenzymes in normal testis and spermatozoa of adult man

Summary Adult human testicular tissue contains up to six previously undescribed lactate dehydrogenase (LDH) isoenzymes in addition to the five LDH isoenzymes normally found and the sixth found in spermatogenic cells and spermatozoa, LDH-X. Additional LDH isoenzymes were also found in spermatozoa but not in seminal fluid or in serum. After electrophoresis one additional LDH isoenzyme of testicular tissue was localized between LDH-1 and LDH-2, two between LDH-2 and LDH-3, two between LDH-3 and LDH-4, and two between LDH-4 and LDH-5. These localizations indicate that the additional LDH isoenzymes are tetramers combining the A and B subunits of the five normal LDH isoenzymes and the C subunit of LDH-X. The additional LDH isoenzymes may be important in the metabolism of spermatogenic germ cells and spermatozoa.     

Effect of coenzymes and temperature on the process of in vitro refolding and reassociation of lactic dehydrogenase isoenzymes.

Dissociation and deactivation of the H4 and M4 isoenzymes of lactic dehydrogenase in strong denaturants may be reversed with a yield of reactivation up to 100%. The products of reconstitution are indistinguishable from the native enzymes as far as the Michaelis constants and the dissociation constants for substrate and coenzyme as well as spectral and hydrodynamic properties are concerned. The presence of NAD+ and NADH does not affect either the conformational state of the product of reconstitution, or the kinetics of reactivation, using the pure apoenzymes as a reference. At 20 degrees C the kinetics of reactivation for LDH-M4 in the presence and absence of coenzyme may be quantitatively described by a second-order rate equation (k2 = 23.4 +/- 2.6 mM-1S-1) while LDH-H4 is characterized by a uni-bimolecular reaction sequence (k1 = 1.45 +/- 0.45 X 10(-3)-S-1, k2 = 5 +/- 1 mM-1S-1), in agreement with earlier observations (Rudolph, R., et al. (1977), Biochemistry 16, 3384-3390). Regarding the influence of temperature on the rate of reactivation no significant anomalies are detectable within the range of 0-25 degrees C. The (apparent) activation energies, taken from the linear Arrhenius plots, are 58 kcal/mol for the association reaction of LDH-M4, and 41 kcal/mol for the transconformation reaction of LDH-H4.