Lactic Dehydrogenase: Genetic Control in Mana

Brain lactate synthesis in thiamine deficiency: A re-evaluation using1H-13C nuclear magnetic resonance spectroscopy

Region-selective accumulation of brain lactate occurs in TD; however, the mechanisms responsible have not been elucidated fully. (1)H and (13)C nuclear magnetic resonance (NMR) spectroscopy were therefore used to investigate de novo lactate synthesis from [1-(13)C]glucose in vulnerable (medial thalamus) and nonvulnerable (frontal cortex) brain regions of rats made thiamine deficient by administration of the central thiamine antagonist pyrithiamine. De novo synthesis of lactate was increased in the medial thalamus to 148% and 226% of pair-fed control values at presymptomatic and symptomatic stages of thiamine deficiency, respectively, whereas no such changes were observed in the frontal cortex. Administration of a glucose load selectively worsened the changes in medial thalamus. Pyruvate recycling and peripherally derived lactate did not contribute significantly to the lactate increase within the thiamine-deficient brain. Increases in immunolabeling of the lactate dehydrogenase isoenzymes (LDH1 and LDH5) were observed in the medial thalamus of thiamine-deficient animals. Metabolic impairment due to thiamine deficiency thus results in increased glycolysis, increased LDH immunolabeling of neurons and astrocytes and increased de novo synthesis of lactate in brain regions vulnerable to thiamine deficiency. These results are consistent with the notion that focal lactate accumulation participates in the worsening of neurologic symptoms in thiamine-deficient patients.

Lactate dehydrogenase isoenzymes

The analytical procedures for LD isoenzymes include electrophoresis, chromatography, immunochemical and kinetic methods. Electrophoretic methods are generally preferred because the resulting patterns are directly observable and all five isoenzymes are resolved in a single procedure. Chromatographic methods, with the introduction of HPLC, have recently been perfected in terms of speed, resolution, precision and accuracy. Immunochemical methods and kinetic methods are attractive because of their speed and simplicity. Therefore, the latter methods are used mainly for assaying acute myocardial infarction, where generally the determination of LD-1 and LD-2 is sufficient. In all other instances, however, electrophoretic separation is currently preferred. Ion-exchange high-performance procedures are useful prospects, particularly in view of their velocity in comparison with electrophoresis. In general, the LD isoenzymes assay contributes considerably to diagnosis, but the results must be used with an adequate knowledge of biochemistry, physiology and the advantages and drawbacks of the different assay methods used.

Lactate dehydrogenase in rat mitochondria

Small but persistent amounts of L-lactate dehydrogenase (LDH) activity were found in mitochondrial preparations isolated from rat heart, kidney, liver, and lymphocytes. Brain mitochondrial preparations were also isolated, but the results were inconclusive. A variety of cytosolic markers were used and it was found that essentially no cytosolic contamination was present except in brain preparations. A bacterial protease was used along with digitonin fractionation to determine localization of the mitochondrial LDH. Approximately 80% of the LDH activity associated with heart and kidney mitochondrial preparations was on the inside compared to about 40% for liver. Lymphocyte mitochondrial LDH activity was about 70% on the inside. Cytosolic LDH-5 preferentially adheres to outer mitochondrial membrane of liver, kidney, and heart. Agarose gel electrophoresis showed LDH isozymes in mitochondria qualitatively similar to that of the corresponding cytosol except in kidney mitochondrial preparations, where a specific electrophoretic band was found which did not correspond to any of the common LDH isozymes.

Electron microscopic and enzyme investigations of the testicular tissue in infertile males

The ultrastructural characteristics of the testicular tissue in male infertility and the isoenzyme spectrum of some enzymes in sperm cells have been studied. The testicular material was taken by Vilar's method from three healthy males with normospermia and eleven males with hypogonadism, azoospermia and infertility. The material was treated by the routine methods for electron investigation and the observations were done with an electron microscope Opton EM 109. Horizontal electrophoresis of the testicular homogenate was done according to Nance. Malate dehydrogenetic activity (MDX) was rendered according to the method of Shaw and Prasad, and diaphoresis (DP) was carried out according to Brewer. It was found that spermatogenesis was interrupted at the pachytene stage at an ultrastructural level. Biochemical investigations showed that in the infertile testis two other atypical fractions appeared on diaphoresis, while at the malate dehydrogenase, a second fraction had considerably lower intensity as compared to the controls. It is pointed out that some profound disorders developing in the infertile testis affect mainly the germinal cells, which was proved at the ultrastructural level and also by the analysis of the isoenzymes MDH and DF key enzymes of carbohydrate metabolism.

Dystrophic mutation (dy2J) affecting regulation of lactate dehydrogenase (LDH) and pyruvate kinase (PK) in C57BL/6J mice

The genotype difference (dystrophic vs nondystrophic) in the LDH isozymes is observed in kidney. These differences are evident only at birth and at early developmental stages (before the expression of dystrophic symptoms). The tissue specific genotype differences for PK are limited to the thigh muscle (M form) and heart (L form), after the onset of the condition. These differences may reflect the pleiotropic effect of the dy2J locus during the temporal regulation of these and other enzymes implicated in muscular dystrophy (MD).

LDH Calcutta-1: a mutation of the B subunit of human lactate dehydrogenase

The electrophoretic variant of human LDH, Calcutta-1, occurs at phenotypic frequencies of 0-4% throughout India. The variant was examined by various electrophoretic techniques and by heat stability studies. The LD1 (B4) isoenzyme was purified from normal and variant bloods by affinity chromatography and ion-exchange chromatography. A minimum of five Calcutta-1 LD1 bands was demonstrated by isoelectric focusing. Electrophoresis of variant LD1 in high-molar urea-acrylamide denaturing gels resulted in two Calcutta-1 B subunit bands, while normal gels yielded only a single band. Homozygote Calcutta-1 LDH from red cells demonstrated a decreased heat stability, while heterozygote variant LDH showed a normal heat stability. This effect was confirmed when purified LD1's were compared. Evidence is presented suggesting a B-subunit variant showing thermolability in the homozygous form.

Blood protein variation in a population of Ethiopian vervet monkeys (Cercopithecus aethiops aethiops)

Seven small groups of vervet monkeys (Cercopithecus aethiops aethiops), totaling 124 individuals, from Awash National Park, Ethiopia, were trapped and blood samples were obtained. Twenty-three loci were examined by starch gel electrophoresis and four loci, Tf, E, ADA, and PMG2 were found to be polymorphic. The average heterozygosity (H) of the population was calculated to be 5.6%. No significant deviations from Hardy-Weinberg equilibrium proportions occurred and a chi-square test for group homogeneity was also not significant. Average Fst for all polymorphic loci was calculated to be 0.062. This suggests that the entire group functions as a single Mendelian population.

Ontogeny of LDH-isozymes in Mexican Axolotl, Ambystoma mexicanum by thin-layer isoelectric focusing

The ontogeny of lactate dehydrogenase (LDH) isozymes in developing Mexican axolotl, Ambystoma mexicanum was investigated by thin-layer isoelectric focusing in polyacrylamide gel. The isoelectric points (pI values) of the isozymes were determined. The minor components generally remained masked during conventional electrophoresis, but became sharp as isofocusing progressed. We identified in developing eggs and embryos five major LDH isozymes, which could also be traced in the ovarian eggs. All these isozymes, except LDH-1, consisted of one major and one minor component. Heterogeneity in axolotl LDH is reported for the first time. The separated isozymes had pI values from 5.24-6.60. Contrary to observations made by others, it was found that the anodal forms of LDH (PIs 5.24-5.80) were prominent throughout, while the remainder (pIs 6.16-6.60) gradually lost their stainability. It thus appears that isoelectric focusing is a possible method for the analysis of protein mixtures and can be successfully applied to problems of differentiation.

An electrophoretic study of the distribution and properties of human hexokinases

An electrophoretic system which gives a clear separation of human hexokinases HK1, HK2 and HK3 is described. The distribution of the hexokinase isozymes in various human tissues, both adult and fetal, is reported. Some properties of the isozymes were investigated. HK2 was found to be more thermolabile than HK1, and there was also a small but significant difference in molecular size. Unlike HK3, HK1 and HK2 are not inhibited by high glucose concentrations. Screening of red cell lysates from 800 unrelated European individuals revealed no genetic variants of HK1 and HK2. However, in view of their difference in properties, it seems probable that the HK1 and HK2 isozymes are determined by separate gene loci.

A study of lactate dehydrogenase isozymes in rat ova

The presence of subunits A and B has been demonstrated in mature rat ova by several means, including the immunohistochemical method of Coons, use of antisera against LDH-I (B4) and LDH-5 (A4) isozymes, and polyacrylamide gel electrophoresis.

Genetic determination of phenotypic variation in sickle cell trait

Two genetic sources of variation influence the percentage of sickle cell hemoglobin found in heterozygotes. One factor is strongly related to the percentage of hemoglobin S in the carrier parent and appears to be determined by sickle hemoglobin isoalleles, whereas the other is related to racial background and may well be polygenic.

Linkage of lactate dehydrogenase B and C loci in pigeons

Synthesis of lactate dehydrogenase in somatic and gametic tissues of certain avian and mammalian species is controlled by alleles at three loci, A, B, and C. We report breeding experiments with pigeons that conclusively demonstrate linkage between the B and C structural loci in this species. The most probable recombination fraction is zero, and contiguity is not excluded. The upper 95 percent probability limit is 4.5 percent. This tight linkage of two loci that produce closely similar polypeptides suggests that the loci acquired their separate identities through a duplication event. Further-more, the existence of recognizable B- and C-type polypeptides in both the bird and the mammal suggests that the event and the resulting linkage preceded the separation of these fauna. If so, then the linkage has persisted for a very long time.

Human serum α-1-lipoprotein patterns revealed by starch gel electrophoresis

The recognition of different serum alpha-1-lipoproteins patterns was made possible by improved lipoprotein staining and separation methods. Three common and some less common patterns were found. The common alpha-1-lipoprotein patterns, here called S, M and F, were found to differ in their relative frequency in men and women, and to be associated with significantly different serum alpha-1-lipoprotein concentrations.

Supernumerary fractions of lactate dehydrogenase in two malignant gliomas

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Molecular aspects of lens cell differentiation

I have presented a series of observations on macromolecular interactions which occur during the terminal stages of lens cell differentiation. These are summarized in Fig. 2. Other cell types that undergo similar changes are the erythrocyte and skin cells (epidermis) during the process of keratinization. These other cells are also involved in the synthesis of highly specific proteins, and there are indications that molecular alterations similar to those described for the lens may also occur in these cells (26). Thus, elucidation of a specific series of macromolecular initeractions such as those described may provide a basis for the biochemical definition of the terminal stages of cellular differentiation. Differentiation of the reticulocyte, for example, involves inactivation of the nucleus, stabilization of mRNA, and possibly a ribosomal breakdown such as I have described here (26). Furthermore, elucidation of the mechanisms of reactions involving the initiation of tissue-specific protein synthesis and suLbsequent nuclear inactivation, stabilization of mRNA, and breakdown of the ribosomes may provide a basis for defining the mechanisms of terminal cellular differentiation. The lens cell has reached its highest form of cellular differentiation when it has formed the fiber cell. With respect to the mechanism of lens fiber cell formation, we would like to know whether specific biochemical changes such as gamma-crystallin synthesis are intiniately linked to fiber cell formation-that is, whether gamma-crystallins are required to bring about the formation of a fiber cell. The potential for synthesizing gamma-crystallins is inherent in the genome of the cell. This part of the genome is nonfunctional in the epithelial cell. Can these genes be activated without bringing about a simultaneous cellular elongation, nuclear inactivation and loss of cellular replication, stabilization of mRNA, and breakdown of the ribosomes? The degree of coupling or uncoupling of tissue-specific-protein synthesis to morphogenesis is an important part of the mechanism of cellular differentiation. We feel that we have now reached the stage where we can begin to answer these questions.