The susceptibility to exercise-induced muscle damage increases as rats grow larger

Summary Glucose-6-phosphate dehydrogenase and N-acetyl--glucosaminidase activities were both elevated after eccentric exercise indicating that this type of exercise causes muscle damage. Muscle damage as measured by glucose-6-phosphate dehydrogenase activity in the vastus intermedius was greater and occurred later in larger rats indicating that the susceptibility to muscle damage is increased and the repair process delayed in older and larger animals.     

Glucose-6-phosphate dehydrogenase of rat liver peroxisomes

Summary A study was made of the effect of chronic administration of clofibrate on the activity and intracellular localization of rat liver glucose-6-phosphate dehydrogenase. Clofibrate-activated glucose-6-phosphate dehydrogenase was found to be located in peroxisomes.     

Biochemical polymorphism of Japanese quail (Coturnix coturnix japonica): comparison of functionally different proteins (author's transl)]

The polymorphism observed among the enzymes involved in the respiratory metabolism (lactate dehydrogenase, malate dehydrogenase, phosphoglucomutase, phosphohexoseisomerase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase fructose 1-6 diphosphate dehydrogenase) is less important than that of the enzymes physiologically less essential, such as the various esterases, the alkaline phosphatase, the alcohol dehydrogenase, and of the non-enzymatic proteins (ovalbumin, ovoglobulins, ovomucoid, conalbumin, transferrin, etc.).     

Increased susceptibility to lipid peroxidation in skeletal muscles of dystrophic hamsters

Summary The results showed that the total content of lipids, which could be peroxidized with Fe(2+)/ascorbate stimulation in vitro, was 45.4% and 53.7% higher than normal in the dystrophic hamster muscle at the age of 1 and 3 months, respectively. Correspondingly, the susceptibility to lipid peroxidation (stimulated by ADP-chelated iron at 37°C) was 38.6–74.3% higher in dystrophic muscles. The increases were not related to necrotic lesions and inflammation observed. The activities of glucose-6-phosphate dehydrogenase, glutathione reductase, thioredoxin reductase and catalase were increased in dystrophic muscles but those of superoxide dismutases and glutathione peroxidase were unaffected.     

Effect of 5-thio-D-glucose on testicular lipids of mice

Summary Spermatogenesis is reported to be completely inhibited by 5-thio-D-glucose in mice. In an investigation of this inhibition, testicular lipid constituents, namely, total lipids, phospholipids, triacylglycerol, free and total cholesterol, 3-hydroxy-3-methylglutaryl-coenzyme A reductase and NADPH generators like glucose-6-phosphate dehydrogenase, intubation for 21 days. Significant increase in cholesteryl ester, glucose-6-phosphate dehydrogenase activity and malic enzyme and a decrease in free cholesterol and phospholipids were observed.Acknowledgments. We are thankful to the Director, Jawaharlal Institute of Postgraduate Medical Education and Research, Pondicherry 6, India for permission to do the work and Mr T. Natarajan, Department of Biochemistry of ministerial assistance.     

Immobilized subunits can function as an affinity sorbent to purify oligomeric enzymes: The usefulness of hybridization on the solid support

Summary Immobilized dimers of yeast glyceraldehyde-3-phosphate dehydrogenase covalently bound to sepharose were shown to form hybrids with soluble dimers of the homologous enzymes present in crude tissue extracts (rat skeletal muscle, rat, rabbit and bovine hearts, rat liver, rat brain). Immobilized hybrid tetramers were then dissociated to form purified soluble enzymes.     

Aldose metabolism in developing human fetal brain and liver

Aldose reductase, sorbitol dehydrogenase, and glucose-6-phosphate dehydrogenase enzyme activities were studied in human foetal brain and liver at different periods of gestation. Aldose reductase activity in liver disappears after 16 weeks of gestation whereas sorbitol dehydrogenase keeps on increasing in liver as well as in brain. In utero, some glucose metabolism may be mediated through an active sorbitol pathway in human fetuses.     

Effect of the scorpion,Heterometrus fulvipes (C. Koch), venom on some enzyme systems in rat (albino) tissues

Summary Sublethal doses ofHeterometrus fulvipes venom decreased NADP-specific isocitrate dehydrogenase and malate dehydrogenase activity levels and increased NADP-specific glucose-6-phosphate dehydrogenase and alkaline phosphatase activity levels during a 48-h-period.Acknowledgments. D. V. thanks the Council of Scientific and Industrial Research, New Delhi, for awarding a Senior Research fellowship.     

Permeability of Ehrlich ascites cells and spectrophotometric assay of the sub-cellular enzymes

Summary A permeabilization method which allows the assay of intracellular enzymes of the Ehrlich ascites cells is described. The developmental changes in the activity of lactic dehydrogenase and glucose-6-phosphate dehydrogenase of toluene-treated Ehrlich ascites cells were studied.Acknowledgment. M.D. is grateful to CSIR for the award of Junior fellowship.     

Aldose metabolism in developing human fetal brain and liver

Summary Aldose reductase, sorbitol dehydrogenase, and glucose-6-phosphate dehydrogenase enzyme activities were studied in human foetal brain and liver at different periods of gestation. Aldose reductase activity in liver disappears after 16 weeks of gestation whereas sorbitol dehydrogenase keeps on increasing in liver as well as in brain. In utero, some glucose metabolism may be mediated through an active sorbitol pathway in human fetuses.Acknowledgments. These studies were supported by the Indian Council of Medical Research.     

Changes in the G6PDH/6PGDH ratio in the chick brain during development

Summary The profile of the G6PDH/6PGDH ratio at various stages of development was drawn on the basis of the specific activities of glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconic dehydrogenase (6PGDH) found in the embryonic brain of the chick. The ratio value lower than 1, found in the adult chick brain, is a special biochemical feature which emerges at a certain time-point of development, occurring around the middle of the prehatching age.Acknowledgment. This work was supported by grants from M.P.I. and C.N.R.     

Effects of isoproterenol and dopamine on the myocardial hexose monophosphate shunt.

Long-term exposure of rats to isoproterenol and dopamine resulted in an increase of glucose-6-phosphate dehydrogenase activity and a greater availability of 5-phosphoribosyl-l-pyrophosphate in the myocardium. These results are interpreted to indicate an enhanced flow through the hexose monophosphate shunt.     

Guanine nucleotides inhibit poly-L-arginine-induced membrane damage in polymorphonuclear leukocytes

Poly-L-arginine induces a strong release of the cytoplasmic enzyme lactate dehydrogenase from rabbit polymorphonuclear leukocytes, indicating that plasma membrane damage occurs. GTP gamma S, a stable guanine nucleotide, completely inhibits poly-L-arginine-induced LDH release whereas pretreatment of the cells with pertussis toxin gives a moderate inhibition. The results suggest that poly-L-arginine-induced plasma membrane damage is mediated by guanine nucleotide binding structures.     

A study of the enzyme activity in the seminal vesicles of castrated and hormone-replaced castrated mice.

Castration provokes a time-related decrease in weight, protein, beta-glucuronidase and glucose-6-phosphate dehydrogenase activity of seminal vesicles. A dose-dependent stimulation of these parameters is obtained with 5alpha-DHT. Cryproterone acetate counteracts the stimulatory effects due to androgen. Acid and alkaline phosphatases remain largely unaffected by these treatments.     

Effects of isoproterenol and dopamine on the myocardial hexose monophosphate shunt

Summary Long-term exposure of rats to isoproterenol and dopamine resulted in an increase of glucose-6-phosphate dehydrogenase activity and a greater availability of 5-phosphoribosyl-1-pyrophosphate in the myocardium. These results are interpreted to indicate an enhanced flow through the hexose monophosphate shunt.Supported by the Deutsche Forschungsgemeinschaft (Zi 199/1). The excellent technical assistance of Miss G. Steinkopff is gratefully acknowledged.     

Enzymhistochemische Untersuchungen an durstaktivierten neurosekretorischen Zellen der Ratte

Summary In hypothalamic neurosecretory nuclei of rats subject to water withdrawl for 1–14 days, a marked increase in the activities of histochemically detected acid phosphatase, thiamine pyrophosphatase and glucose-6-phosphate dehydrogenase is observed. LDH and SDH activities do not change. Two different cell types can be distinguished by means of the acid phosphatase and TPPase reactions.     

Eptoformazione non ossidativa nel muscolo scheletrico

Summary The so-called non-oxydative heptoformation has been shown in enzymatic preparations of rat skeletal muscle, using as substrates glucose-6-phosphate and fructose-6-phosphate.     

Hemmung von SH-Enzymen durch Ethacrynsäure

Summary Enzymes with essential SH-groups (succinate dehydrogenase, proline oxidase, glycerinaldehyde-3-phosphate dehydrogenase) are inhibited by ethacrynic acid. The concentrations needed are comparable with those known to inhibit energy-linked reactions in mitochondria. It is suggested that the action of ethycrynic acid is not only due to its influence on mitochondrial energy conserving reactions.     

Sul meccanismo della eptoformazione non ossidativa nel muscolo scheletrico

Summary F-1,6-P has been shown to increase the rate of non-oxydative heptoformation from glucose-6-phosphate and fructose-6-phosphate in enzymatic preparations of rat skeletal muscle. The mechanism of this increase — probably due to triose-phosphate, formed by aldolase action on F-1,6-P — is discussed.     

Two-tiered hypotheses for Duchenne muscular dystrophy

New approaches to understanding and designing treatments for Duchenne muscular dystrophy (DMD) may emerge from two hypotheses outlined here. The proposal that growing skeletal muscle is more susceptible to necrosis than adult muscle raises the possibility that less intensive treatments may be sufficient to protect muscles during the adult phase. The second proposal is that a different balance of cell and molecular events contributes to acute necrosis (e.g. resulting from exercise) compared with chronic damage of dystrophic muscle. Validation of such differences presents the potential for more specific targeting of drugs or nutritional interventions to events downstream of the dystrophin deficiency. A deeper understanding of the events arising as an early consequence of dystrophin deficiency in these two situations may strengthen approaches to therapy for DMD designed to improve muscle function and the quality of life. Received 18 December 2007; received after revision 9 January 2008; accepted 25 February 2008