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Activities of marker enzymes of osteoblasts (alkaline phosphatase), osteoclasts (tartrate-resistant isoform of acid phosphatase), and macrophages (tartrate-sensitive isoform of acid phosphatase) in bone tissue forming after osteoinduction on the basis of demineralized bone matrix were under study. Early (1 week) stages of osteosynthesis were characterized by low activity of alkaline phosphatase, acid phosphatase being represented by the tartrate-sensitive isoform. Two-three weeks later alkaline phosphatase activity grew and the tartrate-resistant isoform of acid phosphatase appeared. By the fourth-sixth weeks of osteogenesis alkaline phosphatase activity stabilized at a certain level and acid phosphatase activity still grew at the expense of the tartrate-resistant isoform. Conformity of the enzymologic data to changes in cellular populations in ectopic osteogenesis is discussed.

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A procedure for isolation of inhibitors of thiol-dependent proteinases was developed as well as distribution of the inhibitors in rat hepatocyte subcellular fractions was studied. The procedure involved separation of subcellular fractions by means of differential centrifugation, isolation of acid-thermostable proteins and their following purification using affinity chromatography on immobilized papain. The inhibitors were mainly localized in lysosomal, microsomal and cytosol fractions, whereas their specificity towards papain and lysosomal thiol-dependent proteinases cathepsins B, L, H and C was dissimilar, thus suggesting presence of various forms of inhibitors of thiol-dependent proteinases in these cell fractions.

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Actinomycin D inhibited activation of lysosomal cathepsins A, B, C, D, H and L in peritoneal macrophages, caused by T-dependent antigen (sheep erythrocytes), of mice CBA X C57BL/6 strain. At the same time, the antibiotic stimulated activity of cathepsins A, C, D and H but decreased content of antibody-producing cells in spleen tissue. Inhibition of lysosomal proteinases in macrophages may be responsible for immunodepressive effect of actinomycin D.

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White rat experiments have demonstrated that bone matrix osteoinductive activity (the matrix ability to induce ectopic osteogenesis) is in direct proportion with the transplant mass in cases when this mass is within 0 to 0.16% b. m. A higher transplant mass is not associated with elevated osteoinductive activity. When the transplant masses are equal, their osteoinductive activities are in proportion with their sizes. These regularities should be borne in mind when choosing the transplant mass and shape.

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Experiments were conducted on mongrel male rats to study the dependence of the character of maxillary fracture consolidation on the content of osteo-inducing (01) and osteo-inhibiting (I) proteins in the bone tissue as well as the effect of agents intensifying (parathormone) or reducing (methyluracil) the resorption phase of bone regeneration. It is shown that the ratio of OI and I proteins in the bone tissue determines the healing of the fracture according to the type of uncomplicated or slow consolidation in untreated animals, whereas parathormone administration increases the number of animals with uncomplicated consolidation of the fracture and raises the strength of union of the fragments. Methyluracil fails to produce such on effect. It is suggested that improved regeneration of bone in intensification of the phase of resorption is due to more effective excretion of OI proteins from the injured bone tissue.

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Activity of lysosomal proteinases cathepsins A, B, C, D, H and L was studied in peritoneal macrophages, spleen and thymus of mice CBAXC57BL/6 strain in dynamics of immune response formation to sheep erythrocytes from 0.5 hr to 96 hrs. The most distinct alterations in the enzymatic activity were detected in macrophages. Activity of the enzymes studied was sharply decreased within 0.5 hr after immunization and then increased gradually, attaining maximal rates within 4 days. Two-phase increase in activity of cathepsins D and thiol-dependent proteinases cathepsins B, L and H was found in spleen within 0.5-6 hrs and 96 hrs after the antigen stimulation. Dynamics of individual cathepsins activity was dissimilar in thymus but the activity was mainly increased during 24-48 hrs of the antigen stimulation. The data obtained suggest that activity of lysosomal proteinases was distinctly altered in dynamics of the immune response development attaining its maximal values at the peak phase of humoral immunity formation.

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The effects of steroid (dexamethasone) and nonsteroid (indomethacin) anti-inflammatory drugs on the composition and the osteoinductive activity of bone tissue were studied on rats. Dexamethasone was found to induce bone tissue demineralisation and dose-dependent suppression of the osteoinductive activity, i.e. the ability to cause ectopic osteogenesis. Indomethacin, on the contrary, increases the osteoinductive activity of bone tissue. The findings are suggested to be due to different effect of steroid and nonsteroid anti-inflammatory drugs on the synthesis of prostaglandins and leukotrienes.

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Correlation between the animal's age, degree of mineralization of its bone tissue and the osteoinductive activity of the bone organic matrix was established in experiments with rats of the same litter at an age of 2, 4, 8, 16 weeks. The osteoinductive activity was estimated by the capacity of matrix to induce ectopic osteogenesis using biochemical methods. Bone mineralization increased and the capacity for osteoinduction decreased roughly 1,5-fold with the age of donor animals. It is suggested that the reduction of osteoinductive potencies is based on the decrease in lability of the bond between the protein osteoinducer and the collagen matrix, as shown by unequal sensitivity of bone matrix of rats of different age to the doubling of the shortest possible time of bone demineralization.

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10-fold decrease of alpha-tocopherol content in blood serum, distinct increase in hemolysis of erythrocytes and activation of lactate dehydrogenase in blood plasma were found in rats kept on a vitamin E deficient diet within 2 months as compared with control. Content of alpha-tocopherol was decreased in myocardium 3.4-fold and in skeletal muscles--5.4-fold. Lipid peroxidation was activated in myocardium and skeletal muscles under conditions of vitamin E deficiency. Content of diene conjugates and Schiff bases was increased by 30-60% in these tissues; content of malonic dialdehyde--the secondary product of lipid peroxidation--was increased in myocardium by 60% and in skeletal muscles--4-fold. Activity of lysosomal enzymes was altered only slightly in myocardium, whereas in skeletal muscles unsedimented activity of acid phosphatase was distinctly increased. The activation of impairing factors observed led to deterioration of Ca2+ transport functions of membranes in myocardium by 30% and in skeletal muscles--4-fold. The data obtained suggest that heart muscle is better protected against vitamin E deficiency as compared with skeletal muscle. Physiological importance of these results is discussed.

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Activation of lipid peroxidation during myocardial ischemia may be determined by the reduction of the enzymatic antioxidant cell protection. Such a conclusion has been drawn on the basis of an analysis of variation in the activity of superoxide dismutase, glutathion peroxidase and catalase in experimental myocardial ischemia in rats, induced by ligation of the left descending artery of the heart. In the early period of ischemia (1-3 h) the activity of superoxide dismutase and glutation peroxidase markedly decreases. In the periischemic zone, the fall in the enzymatic activity is not so pronounced. The activity of the enzymes does not reach the basic level 5 days after the operation.

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