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PubMed1992

Effect of contact-lens-induced hypoxia on lactate dehydrogenase activity and isozyme in rabbit cornea.

Lactate dehydrogenase (LDH) levels and subunit isozyme patterns in cornea were monitored in 36 albino rabbits wearing thick, rigid, gas-permeable contact lenses for periods of 24 h, 2 and 7 days, and 1 and 3 months. The oxygen transmissibility of the contact lens was 15.3 x 10(-9) (cm/s) (ml O2/ml mm Hg). The activity of LDH in corneal tissue decreased according to the duration of lens wear. The LDH isozyme patterns shifted with lens wear from LDH1,2,3 (heart type, aerobic) to LDH4,5 (skeletal muscle type, anaerobic). The cornea swelled 8.8% with overnight contact lens wear, with increased swelling (11-12%) after further continuous lens wear. After contact lens removal, however, the LDH activity and the isozyme pattern returned to normal, and the corneal thickness quickly returned to normal. Based on these observations, it is suggested that LDH in rabbit corneas was physiologically affected by lens-induced hypoxia, but these changes were reversible. These results might further suggest that tear LDH levels in the human contact lens wearer could provide an ongoing assessment of the tolerance of the lens by the ocular surface.

Animals↗
PubMed1999

A general method for relieving substrate inhibition in lactate dehydrogenases.

The mutation S163L in human heart lactate dehydrogenase removes substrate inhibition while only modestly reducing the turnover rate for pyruvate. Since this is the third enzyme to show this behaviour, we suggest that the S163L mutation is a general method for the removal of substrate inhibition in L-LDH enzymes. Engineering such enzymatic properties has clear industrial applications in the use of these enzymes to produce enantiomerically pure alpha-hydroxy acids. The mutation leads to two principal effects. (1) Substrate inhibition is caused by the formation of a covalent adduct between pyruvate and the oxidized form of the cofactor. The inability of S163L mutants to catalyse the formation of this inhibitory adduct is demonstrated. However, NMR experiments show that the orientation of the nicotinamide ring in the mutant NAD+ binary complex is not perturbed. (2) The mutation also leads to a large increase in the KM for pyruvate. The kinetic and binding properties of S163L LDH mutants are accounted for by a mechanism which invokes a non-productive, bound form of the cofactor. Molecular modelling suggests a structure for this non-productive enzyme-NADH complex.

Enzyme Inhibitors↗
PubMed1994

Cloning, sequencing and comparison of three lactococcal L-lactate dehydrogenase genes.

The conversion of pyruvate to lactate is a key feature of lactococcal strains. The enzyme which facilitates this conversion, L-lactate dehydrogenase (LDH), and the gene which encodes it (Idh), are therefore of great significance. This paper presents the cloning and DNA sequence analysis of three further lactococcal genes which are of key importance in the genetic manipulation of commercial starter strains. The Idh gene from Lactococcus lactis subsp. Lactis biovar diacetylactis BU2-60 has been isolated from a lambda library and sequenced. The Idh gene from L. lactis subsp. cremoris NCDO 762 and that from L. lactis subsp. Lactis IL1403 have been amplified by the polymerase chain reaction (PCR) and sequenced. These DNA sequences and deduced amino acid sequences have been compared with those from L. lactis subsp. Lactis MG1363. The LDHs from L. lactis subsp. Lactis MG1363 and L. lactis subsp. cremoris NCDO 762 are 99.4% homologous. The LDHs from L. lactis subsp. lactis MG1363 and L. lactis subsp. Lactis IL1403 are 96.4% homologous. The LDHs from L. lactis subsp. lactis IL1403 and L. lactis subsp. lactis biovar diacetylactis BU2-60 are 99.9% homologous. Our results provide further evidence that L. lactis subsp. Lactis MG1363 and other L. lactis subsp. Lactis NCDO 712 derived strains should be reclassified as Lactococcus lactis subsp. cremoris.

Amino Acid Sequence↗
PubMed1986

[Endomyocardial biopsy in the monitoring of treatment with anthracyclines. Value of the assay of lactate dehydrogenase and its isoenzymes].

Determination of intramyocardial lactate dehydrogenase (LDH) and its isoenzymes (LDH 1 to 5) has been conducted on biopsy material obtained from the right ventricle in 18 patients who had received the theoretical maximal dose of anthracyclines. Total LDH activity, expressed in mU/mg of myocardial protein is higher (852.61 +/- 87.98) than in subjects with good left ventricular function (334 +/- 208), p less than 0.02. The activity of LDH 1 is decreased in the treated group, whereas that of LDH 3,4 and 5 is raised: LDH 1 = 41.95 +/- 7.25 per cent instead of 47.76 +/- 7.93 per cent (p less than 0.03); LDH 3 = 15.34 +/- 5.09 per cent instead of 9.18 +/- 4.56 per cent (p less than 0.05). The H/M ratio (H = fractions of heart isoenzymes; M = fractions of muscle isoenzymes of LDH) is decreased in the treated group: H/M = 4.06 +/- 1.13 instead of 5.30 +/- 1.80 (p less than 0.01). When the histological lesions are minimal (stage 1 or 1.5 of Billingham), the H/M ratio is not altered: 4.92 +/- 1.02. When the lesions attain or exceed stage 2, the H/M ratio is significantly decreased: 3.74 +/- 0.82. These results, which indicate an increase in anaerobic metabolism, add quantitative information to the histological study.

Adolescent↗
PubMedDate not supplied

Isoenzymatic diagnosis of filariae: a method for separation of lactate dehydrogenase isoenzymes from Molinema dessetae (Nematoda: Filarioidea).

Lactate dehydrogenase (LDH) is highly active in filariae and could be a valuable tool for phyllogeny studies. Unfortunately, the isoenzymatic diagnosis of filariae is often difficult for LDH because of a poor mobility of the enzymes in starch gels which are the most commonly used in such studies. We propose here a method to separate filarial LDH isoenzymes using disc electrophoresis. The experiments were carried out on male and female Molinema dessetae in order to compare their respective isoenzymes. The study of several parameters such as buffer systems, percentage of bisacrylamide and progression time led to optimize the enzyme separation. LDH from male and female filariae were compared to mammal LDH-H4 and LDH-M4. Five and four LDH isoenzymes were found, respectively, in male and female worms. Relative concentration of each isoenzyme diverged between male and female worms. Mammal muscle LDH-M4 type moved between LDH2 and LDH3 from female worms, and between LDH1 and LDH2 from male worms. Mammal heart H4 type enzyme was very different in electrophoretic mobility. The ratio of each isoenzyme was determined by densitometry. The major isoenzymes from female worms will be studied as a biochemical target for chemotherapeutic attack.

Animals↗
PubMed1996

Methods for the separation of lactate dehydrogenases and clinical significance of the enzyme.

Lactate dehydrogenase (LDH), an ubiquitous enzyme among vertebrates, invertebrates, plants and microbes was discovered in the early period of enzymology. The enzyme has been dissolved in several distinguishable molecular forms. In mammals, three types of subunits encoded by the genes Ldh-A, Ldh-B and Ldh-C give rise to a selected number of tetrameric isoenzymes. LDH-A4, LDH-B4 and the mixed hybrid forms of the A- and B-subunits are present in many tissues but with certain distribution patterns. LDH-C4 is confined in mammals to testes and sperm. Numerous techniques have been employed to purify, characterize and separate the different forms of the enzyme. This report deals with the main protocols and procedures of purification of LDH and its isoenzymes including chromatographic and electrophoretic methods, partitioning in aqueous two-phase systems and precipitation approaches. In particular, affinity separation techniques based on natural and pseudo-biospecific ligands are described in detail. In addition, basic physico-chemical and kinetic properties of the enzyme from different sources are summarized in a second part, the clinical significance of the determination of LDH in diverse body fluids in respect to the total activity and the isoenzyme distribution in different organs is discussed.

Animals↗
PubMed1997

Involvement of Glu-264 and Arg-235 in the essential interaction between the catalytic imidazole and substrate for the D-lactate dehydrogenase catalysis.

For Lactobacillus pentosus D-lactate dehydrogenase, the binding of 2-ketoacids is markedly stabilized through interactions between the protonated imidazole of His-296, an acid/base catalyst of the enzyme, and the carbonyl oxygen of 2-ketoacids. The replacement of Arg-235 with Gln destabilized the inhibitory binding of oxamate much more than that of formate, acetate, or propionate, and the Arg to Lys substitution specifically diminished only oxamate binding. On the other hand, replacement of a conserved Glu, Glu-264, with Gln severely impaired the enzyme activity and markedly reduced affinity to 2-keto acids. The pH dependence of the oxamate inhibition revealed that the substitutions of Arg-235 and Glu-264 induced a great loss of the imidazole-carbonyl interaction. However, replacement of Glu-264 with Asp, another acidic amino acid, affected the enzyme function less than the Glu to Gln substitution. In addition, both the Arg-235 and Glu-264 substitutions induced marked increases in the primary isotope effect on the catalysis, suggesting that these amino acids stimulate the hydrogen transfer step in the catalysis. We concluded, therefore, that the guanidino and carboxyl groups of Arg-235 and Glu-264, respectively, cooperatively promote the essential imidazole-substrate interaction, enhancing the substrate binding and catalysis.

Arginine↗
PubMed2002

Selective recovery of lactate dehydrogenase using affinity foam.

Selective isolation of lactate dehydrogenase (LDH) from porcine muscle extract was studied using foam generated from the vigorous stirring of a non-ionic surfactant, Triton X-114 derivatized with Cibacron blue. The cloud point of the surfactant-dye conjugate was higher than that of the native Triton X-114, and also the foam prepared from the affinity surfactant was more rigid taking a longer time to collapse. The equilibrium dissociation constant between pure LDH and surfactant-dye conjugate was 5.0 microM as compared to the value of 2.2 microM for the enzyme and free dye as measured by differential spectroscopy. The isolation procedure involved mixing of the porcine muscle extract with the affinity foam, separating and collapsing the foam, and warming the solution formed to 37 degrees C to yield the surfactant-dye phase and an aqueous phase containing the enzyme. The effect of surfactant concentration and protein load on enzyme recovery and purification was investigated. Under optimal conditions, LDH was quantitatively recovered with high purification factor in a very short time. Both recovery and purification were higher when foam prepared from an equivalent mixture of surfactant-dye conjugate and unmodified surfactant was used. The selectivity of interaction between LDH and detergent-dye conjugate was confirmed by lowered recovery when NADH was included during the binding step.

Affinity Labels↗
PubMed1988

Atypical patterns of lactate dehydrogenase isoenzymes in acute myocardial infarction.

Total lactate dehydrogenase (LD; EC 1.1.1.27) activity in serum and LD isoenzymes were quantified in 190 patients with acute myocardial infarction (AMI) 24, 48, and 72 h after admission. In 90% of the 570 blood specimens an LD isoenzyme pattern typical of AMI (LD-1/LD-2 greater than 0.76) was found. The other 56 blood specimens showed an LD isoenzyme pattern atypical of AMI (LD-1/LD-2 less than 0.76). They were divided into three groups: 28 specimens with isomorphic pattern (relative increase in all five LD isoenzymes); 18 with relatively increased LD-3 proportion (greater than 35%); and 10 specimens with increased LD-5 proportion (greater than 10%). No difference was found in mean total LD activity in serum between the typical isoenzyme group and the three atypical groups. The LD isomorphic pattern was found in 60% of AMI patients complicated by cardiogenic shock. Fifty percent of AMI patients admitted with pulmonary edema showed increased LD-3 proportion and half of the patients with AMI and congestive heart failure, predominant right, demonstrated increased LD-5 proportion. We conclude that although most patients with AMI present at diagnosis with a typical LD isoenzyme pattern, it is important to recognize that some may present with atypical LD isoenzyme patterns, which may be associated with specific AMI complications.

Adult↗
PubMed1984

Composition of a suppressor factor that inhibits the immune response to lactate dehydrogenase B.

Hybridomas obtained by fusion of lactate dehydrogenase B (LDHB)-activated suppressor T (Ts) cells with the BW5147 thymoma produce a suppressor factor (TsF) that inhibits the proliferation of LDHB-activated helper T (Th) cells. A similar factor (TsE) is contained in the extract of suppressor hybridomas. Both TsF and TsE are specifically retained by LDHB-immunoadsorbent columns. Both consist of two components, an antigen-binding component (ABC) and possibly a major histocompatibility complex (MHC) component. The latter reacts with certain monoclonal antibodies specific for MHC determinants. The two components are covalently associated in the TsF and noncovalently associated in TsE. Mixing of the two components reconstitutes the activity of the TsF or TsE. Disruption of the ABC's tertiary structure results in its inability to reconstitute suppressive activity on mixing with the MHC components. The ABC may contain an intrachain disulphide bond(s). Suppression is obtained when Th cells are incubated first with the ABC and then with the MHC component or vice versa, provided that the incubation period is at least 4 h. The MHC component is also produced by nonsuppressor hybridomas but not by mitogen-stimulated blasts or by the parental thymoma. The TsF is a glycoprotein with a molecular weight of about 120,000 to 160,000. The molecular weight of the ABC is about 76,000-86,000 and of the MHC component about 30,000-37,000.

Animals↗
PubMed1987

Chemically crosslinked lactate dehydrogenase: stability and reconstitution after glutaraldehyde fixation.

Lactate dehydrogenase (LDH) from pig heart was stabilized in its tetrameric state by crosslinking with glutaraldehyde. The product (containing 82% tetramers, 9% dimers, 6% monomers, and 3% aggregates) retained up to approximately equal to 60% of its original activity without detectable changes in the spectral and catalytic properties of the enzyme. Fixation of the native quaternary structure enhances the stability of the enzyme: the equilibrium transitions of heat and guanidine deactivation are shifted from 60 to 65 degrees C and CG.HCl = 0.3 to 1.0 M, respectively. Deactivation and denaturation of the crosslinked enzyme do not coincide: the equilibrium transition of fluorescence emission at CG.HCl approximately equal to 3.5 M is paralleled by a significant decrease in cooperativity. The kinetics of thermal denaturation allow structural transitions within a partially crosslinked, native-like species (less than or equal to 10%) to be separated from the unfolding of the fully crosslinked enzyme. The corresponding first-order rate constants at CLDH = 10 micrograms/ml and 60 degrees C are 4.5 X 10(-4) and 2.7 X 10(-5)s-1, respectively. The yield of reconstitution of the crosslinked enzyme after acid denaturation does not exceed 30%; the rate of reactivation is fast due to the significant residual structure of the acid-denatured enzyme. Rate-determining association (which dominates the reconstitution of the unmodified enzyme) does not contribute to the kinetic mechanism. After complete randomization in 6 M guanidinium chloride, incorrect near-neighbor interactions between the crosslinked subunits essentially block the reconstitution of the native structure and function.

Animals↗
PubMed1977

Interconverting measurements of human lactate dehydrogenase activities in three buffers.

The lactate-to-pyruvate reaction for serum lactate dehydrogenase (LD) is most frequently assayed in one of three buffers, pyrophosphate (PPi), tris(hydroxymethyl)amino-methane (Tris), or 2-amino-2-methyl-1-propanol (AMP). We described interconverting results for serum samples and for highly purified LD isoenzymes I (dissolved in one of these matrixes) assayed in these buffers under optimized reaction conditions. The equation for converting results obtained for sera in Tris (x) to those in PPi(y) (both at 30 degrees C) is y = 0.74x+10 (n = 98). Since AMP is used extensively in Technicon procedures, we determined the LD activity of sera with an SMA 12/60, at 37 degrees C. The equation for convering these AMP results to results obtained in PPi at 30 degrees C is y = 0.45x-16 (n = 90). Very different equations were obtained with highly purified LD isoenzyme I maintained in two different matrixes and with both isoenzymes assayed in the same matrix. The matrix in which LD is dissolved and the proportion of various LD isoenzymes affect the magnitude of difference in observed LD activity under various conditions. Therefore, in clinical laboratories that use more than one analytical method or when conversion equations are used in the comparison of interlaboratory results, it is important to define the LD source, isoenzyme content, and the matrix, as well as the reaction conditions, and to use many samples with a wide range of activities when determining the conversion equations. For any changes in reagent source, substrate concentration, or alteration in procedure, a new normal range and new conversion equations should be determined.

Buffers↗
PubMed1989

Lactate dehydrogenase isozymes in xenotropic virus producing mice.

Lactate dehydrogenase (LDH; E.C. 1.1.1.27) isozymes were compared in three inbred strains of mice, and two strains of wild mice, as well as the F1 hybrids and other genetic crosses involving two of the inbred strains. The strains examined were NZB/B1NJ, 129/J and C57BL/6J, Mus musculus molossinus and M. musculus castaneus. Genetic crosses were made between the xenotropic virus-producing NZB and the non-virus producing 129/J mice. Tissue specificity of LDH in these strains was studied using homogenates of kidney, liver, spleen and thymus. Polymorphism of the enzyme was studied by agarose gel electrophoresis. Enzyme polymorphism in the tissues of NZB and 129/J has not been previously reported. The liver and spleen tissues of 129/J showed the absence of LDH-1 and LDH-2 isozymes. Thymic homogenates of NZB showed a lack of expression of LDH-1, LDH-2 and LDH-3 isozymes. The F1, F2 and the backcross progeny from genetic crosses involving NZB, and 129/J mice showed an isozyme pattern more similar to the non-virus-producing 129/J strain than the virus-producing NZB. Evidence of genetic regulation at the LDH-B subunit appears to be the reason for the differential expression of the isozymes in NZB and 129/J strains. The other inbred strain of mice, C57BL/6J, also showed a greater similarity to the 129/J strain than NZB. The two strains of wild mice were similar in their expression of LDH-isozymes between each other and to the 129/J strain, with respect to the liver and spleen tissues.

Animals↗
PubMed1990

Large-scale purification of bovine brain lactate dehydrogenase by affinity chromatography on immobilized colchicine.

Lactate dehydrogenase (LDH) [EC 1.1.1.27] in a crude extract (40-80% ammonium sulfate fraction) of bovine brain was adsorbed on an immobilized colchicine column and specifically eluted by addition of 1 mM NADH. The purity and subunit composition of the pooled LDH were estimated by two-dimensional gel electrophoresis. With an increase of NaCl concentration from 0 to 2.0 M, ligand saturation of LDH on immobilized colchicine increased from 6.8 to 14%, whereas that on immobilized Cibacron blue F3GA decreased from 2.1 to 0%. In the presence of high NaCl concentration, immobilized colchicine enabled both large- and small-scale purification of LDH by affinity chromatography and resulted in a yield of 117 mg from 1 kg of bovine brain in the presence of 2.5 M NaCl or higher recoveries of 54-96% from various tissues of one rat in the presence of 1.0 M NaCl. These results indicate that immobilized colchicine is an excellent adsorbent for the isolation and purification of LDH by affinity chromatography and has a high LDH-adsorbing capacity dependent upon a high NaCl concentration. Kinetic studies revealed that colchicine apparently competed with cofactor NAD for the active site of LDH and the Ki values of colchicine decreased with an increase of NaCl concentration. The chemical specificity of the colchicine-binding site of LDH was studied by the use of colchicine analogues and it is concluded that both the tropolone moiety (C-ring) and the amido bond in a side chain of colchicine structure are essential to the colchicine-LDH interaction.

Animals↗
PubMed1985

Creatine kinase and lactate dehydrogenase in the muscles encountered during median sternotomy and in the myocardium of the cardiac chambers.

The validity of using creatine kinase MB and lactate dehydrogenase serum isoenzymes to confirm the diagnosis of perioperative myocardial infarction in patients who have had cardiac operations has been questioned, since both have been detected in skeletal muscles. Little is known concerning the concentration of either isoenzyme in the muscles routinely encountered during median sternotomy. Since we have previously shown that the dog is an adequate model in which to study creatine kinase and lactate dehydrogenase isoenzymes, eight healthy dogs were placed under general anesthesia and 1 gm blocks were resected from selected muscles (intercostals, rectus abdominis, diaphragm, and sternothyroid) and from the walls of all four cardiac chambers. Each 1 gm block was homogenized individually in Ringer's lactate, centrifuged, and the supernatants were analyzed for total creatine kinase and lactate dehydrogenase activity by spectrophotometry. Isoenzymes were determined by agarose gel electrophoresis. The study shows that the chest wall muscles and atrial myocardium have appreciable quantities of creatine kinase MB. Hence, serum creatine kinase MB bands in the perioperative period can be generated by manipulation of chest wall muscles and the atrial wall as well as by infarction of the ventricular myocardium.

Animals↗
PubMed1994

Contribution of a buried aspartate residue towards the catalytic efficiency and structural stability of Bacillus stearothermophilus lactate dehydrogenase.

The X-ray structure of lactate dehydrogenase (LDH) shows the side-chain carboxylate group of Asp-143 to be buried in the hydrophobic interior of the enzyme, where it makes hydrogen-bonding interactions with both the side-chain hydroxyl group of Ser-273 and the main-chain amide group of His-195. This is an unusual environment for a carboxylate side-chain as hydrogen bonding normally occurs with water molecules at the surface of the protein. A charged hydrogen-bonding interaction in the interior of a protein would be expected to be much stronger than a similar interaction on the solvent-exposed exterior. In this respect the side-chain carboxylate group of Asp-143 appears to be important for maintaining tertiary structure by providing a common linkage point between three discontinuous elements of the secondary structure, alpha 1F, beta K and the beta-turn joining beta G and beta H. The contribution of the Asp-143 side-chain to the structure and function of Bacillus stearothermophilus LDH was assessed by creating a mutant enzyme containing Asn-143. The decreased thermal stability of both unactivated and fructose-1,6-diphosphate (Fru-1,6-P2)-activated forms of the mutant enzyme support a structural role for Asp-143. Furthermore, the difference in stability of the wild-type and mutant enzymes in guanidinium chloride suggested that the carboxylate group of Asp-143 contributes at least 22 kJ/mol to the conformational stability of the wild-type enzyme. However, there was no alteration in the amount of accessible tryptophan fluorescence in the mutant enzyme, indicating that the mutation caused a structural weakness rather than a gross conformational change. Comparison of the wild-type and mutant enzyme steady-state parameters for various 2-keto acid substrates showed the mutation to have a general effect on catalysis, with an average difference in binding energy of 11 kJ/mol for the transition-state complexes. The different effects of pH and Fru-1,6-P2 on the wild-type and mutant enzymes also confirmed a perturbation of the catalytic centre in the mutant enzyme. As the side-chain of Asp-143 is not sufficiently close to the active site to be directly involved in catalysis or substrate binding it is proposed that the effects on catalysis shown by the mutant enzyme are induced either by a structural change or by charge imbalance at the active site.(ABSTRACT TRUNCATED AT 400 WORDS)

Aspartic Acid↗
PubMed1997

The ldhA gene encoding the fermentative lactate dehydrogenase of Escherichia coli.

Under anaerobic conditions, especially at low pH, Escherichia coli converts pyruvate to D-lactate by means of an NADH-linked lactate dehydrogenase (LDH). This LDH is present in substantial basal levels under all conditions but increases approximately 10-fold at low pH. The ldhA gene, encoding the fermentative lactate dehydrogenase of E. coli, was cloned using lambda 10E6 of the Kohara collection as the source of DNA. The IdhA gene was subcloned on a 2.8 kb MluI-MluI fragment into a multicopy vector and the region encompassing the gene was sequenced. The IdhA gene of E. coli was highly homologous to genes for other D-lactate-specific dehydrogenases but unrelated to those for the L-lactate-specific enzymes. We constructed a disrupted derivative of the ldhA gene by inserting a kanamycin resistance cassette into the unique KpnI site within the coding region. When transferred to the chromosome, the ldhA::Kan construct abolished the synthesis of the D-LDH completely. When present in high copy number, the ldhA gene was greatly overexpressed, suggesting escape from negative regulation. Cells expressing high levels of the D-LDH grew very poorly, especially in minimal medium. This poor growth was largely counteracted by supplementation with high alanine or pyruvate concentrations, suggesting that excess LDH converts the pyruvate pool to lactate, thus creating a shortage of 3-carbon metabolic intermediates. Using an ldhA-cat gene fusion construct we isolated mutants which no longer showed pH-dependent regulation of the ldhA gene. Some of these appeared to be in the pta gene, which encodes phosphotransacetylase, suggesting the possible involvement of acetyl phosphate in ldhA regulation.

Amino Acid Sequence↗
PubMed1984

Lactate dehydrogenase isoenzymes in the lungs of sheep with acute and chronic pneumonia.

Total lactate dehydrogenase and the absolute and percentage levels of its isoenzymes were measured in lung lesions and macroscopically normal areas of lung from lambs with chronic proliferative exudative pneumonia and acute pasteurella pneumonia. Lung lesions had a higher total enzyme activity which was associated mainly with increases in the activity of the LDH4 and LDH5 isoenzymes, particularly in chronic pneumonia, and gave lung lesions a considerable potential for altering the serum isoenzyme distribution. Thus, the nature of any changes in the serum isoenzyme distribution will depend on whether the isoenzymes are released from abnormal or normal areas of lung. This appears to be the first report on lactate dehydrogenase isoenzymes in ovine pneumonia.

Animals↗