[Influence of small doses of fractionated X-ray radiation on the activity of histone-specific proteases and the content of malonic dialdehyde in chromatin of the cells of rat liver]

The fractionated X-ray irradiation resulted in accumulation of malonic dialdehyde (MDA) in chromatin of the cells of rat liver and activation of nuclear endogenous histon-specific proteases. Seven days after the termination of irradiation, the activity of the nuclear proteases returned to the control level and the MDA level remained 10% above the control parameter. The correlation (r = 0.71) of the processes of MDA accumulation in chromatin and activation of histon-specific proteases in the cells of rat liver after the termination of irradiation showed that these processes were coupled. Transplantation of Guerin's carcinoma to the irradiated animals caused the changes in nuclear proteolysis of the histones and MDA level in chromatin of the tumor-carrier liver cells, which lessened the influence of preliminary X-ray irradiation on rats.

Enhancement of protease activity involved in modulation of cell mutability by microgravity stress in UVC-irradiated human cells

It is an intriguing question whether gravity-changing stress modulates human cell mutability. To resolve this problem, it is necessary to determine the cellular events leading to modulation. We previously detected protease activation just after UV (UVC, principally 254 nm wavelength) irradiation followed by hypomutability in cultured human cells. We here investigated whether UV-activated protease activity is affected in human UVAP-1 cells exposed to gravity-changing stress prior to UV irradiation.

Radiation technology in the preparation of polyethylene oxide hydrophilic gels and immobilization of proteases for use in medical practice

This paper deals with the development of a technology for making a hydrophilic gel of polyethylene oxide reception in which radiating ability is employed to cause cross-linking of polymers in a water solution. The gel of polyethylene oxide was shown to be non-toxic, contain 5-50% of polymer and be useful in composite medicinal forms along with biologically active substances including Bac. subtilis proteases. Proteases immobilized in the gel possess high thermal stability and proteolytic activity and are readily applied in medicine. The effect of immobilized proteolytic and glucolytic enzymes of Bac. subtillis (Immozimase) on the warm ischemia-reperfusion (I/R) which can cause hepatic and jejunum injury was also studied. These enzymes were immobilized on water-soluble polymer polyethylene glycol by means of an electron beam. The number of degranulated mast cells as well as serum ALT after I/R in the group with Immozimase was decreased to almost half as compared with the control group. Pretreatment with Immozimase resulted in significant reduction of hepatic and gut neutrophil accumulation as compared with control animals. It was concluded that Immozimase has a protective effect for hepatic and gut ischemia/reperfusion, and this effect seems to be associated with prevention of leukocyte accumulation.

Increased cell surface protease activity in UV-irradiated cells undergoing apoptosis

UVB-irradiated HeLa cells undergoing apoptosis have increased cell surface protease (CSP) activity compared to viable or necrotic cells. In order to elucidate whether caspase 3 plays a role in the activation of CSP in cells undergoing apoptosis, HeLa cell cultures were pre-treated with the caspase inhibitor, DEVD, prior to being exposed to 500 Jm(-2) UVB. DEVD significantly inhibited caspase 3 activity in cells undergoing apoptosis, but did not affect the activation of CSP in these cells. The findings suggest that the activation of CSP in apoptotic cells is unrelated to caspase 3 activity.

The effect of photodynamic action on two virulence factors of gram-negative bacteria

Photodynamic therapy could provide an alternative to antibiotics for the treatment of local infections since a wide range of microorganisms have been shown to be susceptible to killing by photodynamic action (PDA) in vitro. The purpose of this study was to determine whether PDA was also able to affect the potency of two key bacterial virulence factors--lipopolysaccharide (LPS) and proteases. Suspensions of LPS from Escherichia coli and culture supernatants containing proteases of Pseudomonas aeruginosa were exposed to red light in the presence of toluidine blue O (TBO). The activity of each virulence factor was determined before and after irradiation. The limulus amoebocyte lysate (LAL) assay and the induction of proinflammatory cytokine (interleukin-8 and -6) release from human peripheral blood mononuclear cells (PBMC) were used for assessing the biological activity of LPS. Protease activity was quantified by azocasein hydrolysis. The biological activities of the LPS (both the LAL activity and its ability to induce cytokine release from PBMC) and the proteases were reduced significantly by irradiation with red light in the presence of TBO in a dose-dependent manner with respect to both the light energy dose and the TBO concentration. The ability of TBO-mediated PDA to reduce the activities of key virulence factors may be an additional benefit of using light-activated antimicrobial agents in the treatment of infectious diseases.

[Proteinases activated by gamma irradiation in the nuclei of rat peripheral blood leukocytes]

The nuclei of the peripheral blood leucocytes of rats displayed proteolytic activity (Ca-dependent with pH optimum 8.5 and active at alkaline pH), whose level increases under the influence of gamma-irradiation. These proteases were partially purified and identified. It was shown using gel chromatography, affinity chromatography with casein-sepharose and enzyme-electrophoresis that these proteolytic activities are related to one protein with a molecular mass of 24 kDa or a complex of proteins that do not cleave under the given experimental conditions. The both protease activities are predominantly blocked by inhibitors of cysteine proteases.

The damaging effect of UV rays below 320 nm on the rabbit anterior eye segment. II. Enzyme histochemical changes and plasmin activity after prolonged irradiation

Prolonged irradiation of the rabbit eyes with UVB rays (312 nm) caused serious enzymatic disturbances in the cornea and lens and the development of an inflammatory reaction in the whole anterior eye segment, particularly in the cornea. In the corneal stroma many inflammatory cells with high activities of acid glycosidases and lysosomal proteases were present. This was accompanied with significantly elevated plasmin activity in the tear fluid (1.6 IU/ml). Plasmin appeared also in the aqueous humour (0.8 IU/ml). For the treatment of these changes catalase (1 mg/1 ml saline), aprotinin (100 micrograms/1 ml saline) and catalase-aprotinin mixture (1:1) were applied on the eye surface during irradiation. The catalase-aprotinin mixture was most efficient and decreased plasmin activity in the tear fluid and diminished disturbances of the anterior eye segment. Obviously both, active oxygen species and elevated plasmin activity in the tear fluid contribute to the damage of the anterior eye segment and development of intracorneal inflammation after irradiation of the eye with UVB rays.

[Effect of ionizing radiation on the chromatin fraction components in rat blood lymphocytes]

Changes in the level of blood lymphocyte chromatin degradation and relaxation were investigated after the whole body irradiation with doses up to 0.21 C/kg. It was shown that ionizing irradiation initiated the increase of nuclear endogenous Ca/mg-dependent endonuclease, and protease activities.

[Effect of low doses of external and internal ionizing radiation on proteinases of cells in the rat cerebral cortex of rats]

Single external gamma-irradiation in a dose of 0.5-2 Gy as well as the long-term (30 days) internal irradiation caused by the everyday influx of Cs-137 and Sr-85 isotopes to the organism have been studied for their effect on the activity and properties of histone-specific proteinase from the nuclei of the rat brain cortex cells. It is found out that external irradiation induces a dose-dependent increase of the activity during the first 24 hours after irradiation followed by its decrease 7-30 days later. Internal irradiation induces a decrease of the enzyme activity at the 30th day as well. Certain specificity of the studied indices depending on the type of irradiation has been also observed.

[The effect of low doses of external gamma irradiation on the chromatin structure and activity of the histone-specific proteinases of rat brain cells]

Irradiation of rats with doses of 0.5 to 2 Gy was shown to cause dose-dependent changes in the sensitivity of brain cell chromatin to the effect of DNAase I that were manifested by the increased level of DNA hydrolysis and a high content of the chromatin soluble fractions. The chromatin structure was only partially restored 24 h after irradiation. Changes in the chromatin structure were accompanied by the increase in the histone-specific proteinase activity.

Dynamics of postirradiation intracellular cysteine and aspartic proteinases profiles in proliferating and nonproliferating mammalian cells

Dynamics of postirradiation intracellular cysteine and aspartic proteinases profiles were examined in proliferating and nonproliferating Chinese hamster fibroblasts (V79). The results show that there are significant alterations in cysteine and aspartic intracellular proteinases activity already in the early postirradiation period, which are different in proliferating and nonproliferating cells. Irradiation of the cells examined to low doses and up to 15 Gy induced an increase in cysteine proteinases activity in the early postexposure period, while at higher irradiation doses applied, the activity of these proteinases was decreased. These observations suggest that intracellular proteinases are actively participating in process involving recovery from radiation injury or cell killing.

[Effect of ionizing radiation on the turnover of catalase-degrading proteinase in rat hepatocytes]

A study was made of the influence of whole-body X-irradiation (8 Gy) on the turnover of an individual protein, alkaline proteinase, initiating inactivation of a catalase protein in rat liver. It was shown that the extent to which metabolism of this enzyme in the exposed animals is impaired depends upon its localization. The authors discuss the possibility of a correlation between the decrease in the catalase protein degradation and the level of proteinase activity in hepatocytes of irradiated rat liver.

[Postradiation activation of proteinases associated with the hepatocyte nuclear matrix in rats]

Proteinase activity of the nuclear matrix of rat hepatocytes was 7-8-times as high as that of initial nuclei. Activity of nuclear matrix proteinases was optimum at pH 8-9. Proteolytic activity associated with the nuclear matrix, increased by 1.4-2.8 times 2 h following irradiation with doses from 5 to 30 Gy. Cycloheximide, a protein synthesis inhibitor, administered to animals failed to suppress the radiation-induced increase of proteinase activity of the nuclear matrix.

[Lysosomal proteinase activity in the small intestine and liver of irradiated animals following thermal exposure]

A study was made of a modifying effect of heat on acid proteinase activity in the liver and small intestine tissues of irradiated (6 Gy) albino mongrel mice. During the first few hours following thermal affection proteinase activity in the organs under study was inhibited.

[Effect of gamma irradiation on brain enkephalin hydrolase activity in the rat]

A study was made of the effect of different radiation doses on the brain enzymes degrading enkephalins. Enkephalin aminopeptidase activity decreased during the first 60 min following irradiation with a dose of 774 X 10(-4) C/kg and increased after a dose of 3096 X X 10(-4) C/kg; enkephalinase A exhibited opposite changes. 48 hr after irradiation, enkephalin aminopeptidase activity exceeded the normal level, and no significant changes occurred in encephaliase A activity irrespective of the radiation dose.