Glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase activities in early stages of development in dystrophic chickens

The effect of protein-xanthophyll concentrate (PX) from alfalfa (Medicago sativa L.) on the activity of selected enzymes in the liver cells of fattening pigs

The available Polish and foreign literature contains few reports on the activity of indicator enzymes, especially marker enzymes, which characterize the work of specific cell organelles. Information on enzyme changes induced by experimental dietary factors is also scarce. We postulated that proteinxanthophyll PX alfalfa concentrate would have a positive effect on metabolism in fattening pigs, resulting in improved performance parameters. Therefore the aim of the study was to test the possibility of using enzymes that have not previously been used to assess the biochemical processes taking place following administration of PX. We evaluated the activity of enzymes associated with key biological transformations taking place in the cell, as this makes it possible to assess whether these processes are proceeding normally and to evaluate the response of the body to external factors. The experiment was conducted on 288 finishers (gilts and barrows), all of which were crossbreds (Polish Large White x Neckar), divided into 4 groups according to the dosage and duration of administration of proteinxanthophyll PX concentrate from alfalfa (Medicago sativa L.). The alfalfa concentrate was introduced to the compound feed in place of soybean extraction meal. We analysed the activity of selected marker enzymes: lactate dehydrogenase (LDH), malate dehydrogenase (MDH), succinate hydrolase (SDH), and glucose-6-phosphate hydrolase (G6PC). We found a decrease in the activity of the enzymes in the liver cells of the pigs receiving the PX concentrate as compared to the control, which suggests that the product had a favourable effect on their metabolism. The results confirm the benefit of using proteinxanthophyll PX in pig feed, particularly at a continuous dose of 3%.

Muscle carbonic anhydrase III levels in normal and muscular dystrophia afflicted chickens

Background

The levels and immunohistochemical localization of muscle carbonic anhydrase III (CA-III) in healthy chickens and in muscular dystrophia affected (DA) chickens show that the muscles of diseased animal undergo a progressive increase of enzyme activity.

Methods

An enzyme-linked immunoassay was used to assess the CA-III levels in the muscles and other tissues from eight normal White Leghorn chickens and in two chickens with muscular dystrophy. Immunohistochemical localization of the enzyme in the muscles of these animals was also determined.

Results

The levels of CA-III in the tensor fasciae latae and the superficial pectoral muscles of the DA chickens were higher than the level in normal chickens. The concentrations of CA-III in erythrocytes and plasma from diseased chickens were approximately 15-fold and 1.4-fold higher than in the normal chickens, respectively. In the superficial pectoral and the tensor fasciae latae muscles of diseased chickens, the numbers of strongly stained and weakly stained fibers were greater than that in the normal chickens.

Conclusion

The levels of CA-III in the superficial pectoral muscle, the tensor fasciae latae muscle, plasma and erythrocytes from the chickens with muscular dystrophy were higher than found in normal chickens.

Oxidative stress and the pathogenesis of muscular dystrophies

The muscular dystrophies represent a diverse group of diseases differing in underlying genetic basis, age of onset, mode of inheritance, and severity of progression, but they share certain common pathologic features. Most prominent among these features is the necrotic degeneration of muscle fibers. Although the genetic basis of many of the dystrophies has been known for over a decade and new disease genes continue to be discovered, the pathogenetic mechanisms leading to muscle cell death in the dystrophies remain a mystery. This review focuses on the oxidative stress theory, which states that the final common pathway of muscle cell death in these diseases involves oxidative damage.

Kinetic properties of hexose-monophosphate dehydrogenases. II. Isolation and partial purification of 6-phosphogluconate dehydrogenase from rat liver and kidney cortex

6-Phosphogluconate dehydrogenase (6PGDH) from rat-liver and kidney-cortex cytosol has been partially purified and almost completely isolated (more than 95%) from glucose-6-phosphate dehydrogenase activity. The purification and isolation procedures included high-speed centrifugation, 60-75% ammonium-sulphate fractionation, by which both hexose-monophosphate dehydrogenases activities were separated, and finally the protein fraction was applied to a chromatographic column of Sephadex G-25 equilibrated with 10 mM Tris-EDTA-NADP buffer, pH 7.6, to eliminate any contaminating metabolites. The kinetic properties of the isolated partially purified liver and renal 6PGDH were examined. The saturation curves of this enzyme in both rat tissues showed a typical Michaelis-Menten kinetic, with no evidence of co-operativity. The optimum pH for both liver and kidney-cortex 6PGDH was 8.0. The Km values of liver 6PGDH for 6-phosphogluconate (6PG) and for NADP were 157 microM and 258 microM respectively, while the specific activity measured at optimum conditions (pH 8.0 and 37 degrees C) was 424.2 mU/mg of protein. NADPH caused a competitive inhibition against NADP with an inhibition constant (Ki) of 21 microM. The Km values for 6PG and NADP from kidney-cortex 6PGDH were 49 microM and 56 microM respectively. The specific activity at pH 8.0 and 37 degrees C was 120.7 mU/mg of protein. NADPH also competitively inhibited 6PGDH activity, with a Ki of 41 microM. This paper describes a quick, easy and reliable method for the separation of the two dehydrogenases present in the oxidative segment of the pentose-phosphate pathway in animal tissues, eliminating interference in the measurements of their activities.

The pentose phosphate pathway in skeletal muscle under patho-physiological conditions. A combined histochemical and biochemical study

Over the last 30 years, research into the neuromuscular apparatus, has expanded greatly. Multidisciplinary investigations have rapidly advanced our understanding both of diseases and of the basic neuromuscular mechanisms. The mode of pathological reaction of the neuromuscular apparatus is now quite well understood. The most notable aspect of the reaction of the injured neuromuscular apparatus is the remarkably stereotyped character of the resulting pathological changes as demonstrated by a wide variety of harmful causes, producing surprisingly similar effects. The findings of our combined histochemical and biochemical investigations presented in this monograph, are in complete harmony with the stereotyped character of the pathological changes. For example, it is particularly striking that many affected muscle fibres of patients with muscular dystrophies, congenital myopathies, inflammatory myopathies, metabolic myopathies, endocrine myopathies, or with diseases of the lower motor neuron, display an enhanced activity of both oxidative enzymes of the pentose phosphate pathway. Likewise, we found that experimental animals with disordered skeletal muscles, provoked by different types of agents or treatments, reveal the same marked rise in activity of GPDH and PGDH in the muscle fibres, with a positive correlation between the activity of both enzymes. Other findings of our investigations point to a positive correlation between the activity of GPDH and PGDH on the one hand and that of the non-oxidative enzymes of the pentose phosphate pathway, the enzymes TA, TK, RPI and RPE on the other hand. The rise in activity of PGDH and, in particular, of GPDH is regulated by two different mechanisms. The first represents a rapid control mechanism based on the stimulation of both oxidative enzymes of the pentose phosphate pathway by NADP+ and on their inhibition by NADPH. The other mechanism represents a long-term effect directed at the synthesis of the enzymes. It is this type of mechanism which is responsible for the rise in activity of GPDH and PGDH we observed. The findings obtained with the applied enzyme histochemical techniques clearly demonstrated that the rise in activity of both enzymes is not homogeneously distributed in the disordered skeletal muscles of man and experimental animals. For that reason, in order to obtain reliable quantitative information about enzyme activities in the muscle fibres themselves, the application of biochemical assays on a micro-scale was indispensable. The biochemical assay of enzyme activities was performed on histologically and histochemically selected dissected muscle specimens.(ABSTRACT TRUNCATED AT 400 WORDS)

Lipid peroxide and antioxidant enzymes in muscle and nonmuscle of dystrophic mouse

To determine whether abnormality in redox metabolism occurs specifically in certain individual dystrophic muscles, thiobarbituric acid reactivity, free radical scavengers, and oxidative marker enzymes were measured in the liver, kidney, erythrocytes, heart, and four different individual skeletal muscles from C57BL/6J dy/dy mice. Superoxide dismutases were assayed by specific radioimmunoassays, which enabled the study of a small individual murine muscle. Glutathione peroxidase and catalase were increased markedly in each individual dystrophic skeletal muscle studied and less markedly in the heart. Manganosuperoxide dismutase and thiobarbituric acid reactivity were decreased to a similar extent in each dystrophic skeletal muscle. Cuprozinc superoxide dismutase was decreased in the soleus muscle. Only a minimal biochemical change occurred in nonmuscles. Fumarase activity correlated closely with the level of manganosuperoxide dismutase. These results suggest that muscle protein breakdown occurs independently of lipid peroxidation despite the presence of tissue-specific abnormality of redox metabolism in dystrophic muscle.

Oxidation state of tissue thiol groups and content of protein carbonyl groups in chickens with inherited muscular dystrophy

Indirect evidence suggests that oxidative stress may play a role in the pathogenesis of inherited muscular dystrophy, but the significance and precise extent of this contribution is poorly understood. Compared with normal muscle, significantly higher contents of glutathione, glutathione disulphide, protein-glutathione mixed disulphides and protein carbonyl groups, and significantly lower contents of free protein thiol groups, were found in pectoralis major muscle of genetically dystrophic chickens (the muscle affected by this disease) at 4 weeks of age. Other tissues did not show such marked disease-related differences. Interestingly, the protein pool in normal, but not dystrophic, pectoralis major muscle was relatively less oxidized in relation to the glutathione pool as compared with other tissues studied. The mechanisms by which this unique relationship between the thiol pools is maintained remain unknown. Although the physiological consequences of the increased content of protein carbonyl groups and the altered thiol pools in dystrophic muscle are not clear, the changes evident at such a young age are consistent with the occurrence of oxidative stress and may reflect significant damage to cellular proteins in this disease.

Oxidative stress and muscular dystrophy

Oxidative stress may be the fundamental basis of many of the structural, functional and biochemical changes characteristic of the inherited muscular dystrophies in animals and humans. The presence of by-products of oxidative damage, and the compensatory increases in cellular antioxidants, both indicate oxidative stress may be occurring in dystrophic muscle. Changes in the proportions and metabolism of cellular lipids, abnormal functions of cellular membranes, altered activity of membrane-bound enzymes such as the SR Ca2+-ATPase, disturbances in cellular protein turnover and energy production and a variety of other changes all indicate that these inherited muscular dystrophies appear more like the results of oxidative stress to muscle than any other type of underlying muscle disturbance. Particular details of these altered characteristics of dystrophic muscle, in combination with current knowledge on the processes of oxidative damage to cells, may provide some insight into the underlying biochemical defect responsible for the disease, as well as direct research towards the ultimate goal of an effective treatment.

Pathogenesis of progressive muscular dystrophy: studies on free radical metabolism in an animal model

Evidence to suggest the presence of abnormal metabolism of oxygen free radicals in progressive muscular dystrophy is presented using an animal model. In the superficial pectoral muscles of dystrophic chickens, enzyme activities regulating the metabolism of oxygen free radicals, i.e., catalase, superoxide dismutases and glutathione peroxidase, were significantly elevated within 1 week of hatching. Activities of related enzymes, i.e., glutathione reductase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase were also elevated. In contrast, the specific activity of phosphofructokinase, the rate-limiting enzyme of the glycolytic pathway, was normal during the first 4-week period. These results suggest that there is an increased turnover of oxygen free radicals in the dystrophic muscle. This concept appears important in a further investigation of the pathogenesis and treatment of progressive muscular dystrophies.

Additional biochemical criteria in the differential diagnosis of myositis

Thirty-six biopsy specimens of human biceps and vastus lateralis muscles were examined by histometric analysis and determination of enzyme activities (phosphorylase, triosephosphate dehydrogenase, 3-hydroxacyl-CoA-dehydrogenase, lactate dehydrogenase, hexose isomerase, citrate synthetase, 6-phosphogluconate dehydrogenase). The series included 13 specimens from patients suffering from a benign form of muscular dystrophy (limb girdle and Becker type of muscular dystrophy) and 12 specimens from patients with an acute (n = 5) or chronic (n = 7) form of myositis. Muscle fibres were atrophic in myositis and hypertrophic (with an increased variation of fibre diameters) in muscular dystrophies, as has been shown previously. When myositis samples were compared with either normal or dystrophic muscles, a highly significant lowering of glycolytic enzyme activity was found in chronic myositis, while the activity of 6-phosphogluconate dehydrogenase was elevated to highly significant levels. Measurements of the latter enzyme's activity might be of additional value in differentiating chronic forms of myositis from benign muscular dystrophies.

Free radicals: a potential pathogenic mechanism in inherited muscular dystrophy

Despite years of intensive work, the biochemical defect responsible for the pathogenesis of inherited muscular dystrophy has not been identified either in humans or animal models. This review examines evidence in support of the hypothesis that free radicals may be responsible for muscle degeneration in this disorder. A variety of cellular abnormalities noted in dystrophic muscles can be accounted for by free radical mediated damage. In addition, chemical by-products associated with free radical damage are found in dystrophic muscle tissue from humans and animals with this disease. Various enzymatic antioxidant systems can be enhanced as a normal cellular response to oxidative stress, and such changes are seen both in dystrophic muscle cells and certain other tissues of dystrophic animals. An increased level of free radical damage would follow from either: enhanced production of free radical species, or a deficient component of the cellular antioxidant system, such as vitamin E. The free radical hypothesis of muscular dystrophy can account for data supporting several alternative theories of the pathogenesis of this disease, as well as other observations which have not previously been explained.

Activities of some antioxidative and hexose monophosphate shunt enzymes of skeletal muscle in neuromuscular diseases

The activities of some antioxidative and hexose monophosphate shunt enzymes, as well as of 2 hydrolases were studied in skeletal muscle biopsy specimens taken from 39 patients with neuromuscular diseases and from 15 controls. The activity of Se-dependent glutathione peroxidase was higher in patients with congenital myotonia, whereas in the other diagnostic groups this enzyme activity was the same as in the controls. The Se-independent and total glutathione peroxidase activity of patients in the various diagnostic groups did not differ from the controls. Moreover, no difference were observed in catalase activity between the patient groups and the controls. The activities of the rate limiting enzymes of hexose monophosphate shunt, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase of muscle biopsy samples of various patient groups did not show any significant difference from controls. The activity of a lysosomal hydrolase, beta-N-acetylglucosaminidase, was increased in patients with polyneuropathy and the activity of a nonlysosomal protease, alkaline protease, was high in patients with Charcot-Marie-Tooth disease. The activities of Se-dependent glutathione peroxidase, 6-phosphogluconate dehydrogenase and of both hydrolases showed a significant correlation to the magnitude of muscle atrophy.

Activities of antioxidant enzymes in muscle, liver and lung of chickens with inherited muscular dystrophy

An inherited form of muscular dystrophy in chickens has been used as a model of Duchenne muscular dystrophy. The pectoralis major muscle of chickens with this disease showed a significantly elevated activity of catalase (CAT) one day after hatching, and by 7 days showed elevated superoxide dismutase (SOD), glutathione peroxidase (GPX) and glutathione-S-transferase (GST) activities. Increases were also found in tissues of the dystrophic birds that, unlike the pectoralis muscle, are considered to be unaffected by the pathology of muscular dystrophy. The soleus muscle contained significantly increased levels of SOD and GPX in 1 and 7 day old chickens, and increased GST in 1, 14, and 28 day old birds. CAT was significantly increased in liver from 1 and 7 day old chickens, while GPX was increased in lung from 1, 7 and 14 day old birds. These results support the possibility that excess oxygen free-radicals or altered cellular antioxidant defenses play some role in the pathogenesis of muscular dystrophy.