Gamma-radiation-induced damage of chicken myosin and actin

The single 60Co gamma radiation-induced damage of purified chicken myosin and actin in N2O saturated solution is dose dependent protein cross-linking. The differences in myosin and actin conformation and Mm do not influence the type of radiation-induced damage, but they influence the extent of radiation-induced damage, judged by the lower cross linking of fibrillar myosin compared to actin. The radiolytic behavior of myosin and actin in purified forms is different from their radiolysis in intact muscle, according to the absence of protein fragmentation in the former. The results confirm that industrially sterilized meat may contain significant amount (25- 35%) of structurally altered proteins.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Sonolytic degradation of ovomucin based protein matrix of hen egg white

Sonication of ovomucin based protein matrix of the thick fraction of egg white with the therapeutic ultrasound of 23 kHz frequency and 5µm amplitude causes irreversible decrease of its viscosity down to the limit value of 2.1mPa⋅s. The ultrasound treatment does not affect structure of proteins with lower molecular mass (Mm 3 x 106 g/mol) which form the thick egg white matrix. The results suggest that in analogy with avian egg white matrix, sonication-induced changes in mammalian mucin matrix of joints and tendons may constitute the therapeutical action of ultrasound.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Gamma-radiation-induced damage of proteins in the thick fraction of egg white

The 60Co gamma-ray irradiation of ovomucin based protein network of the thick fraction of egg white in the absence of oxygen causes both protein cross linking and protein fragmentation. Protein fragmentation in the absence of oxygen is interpreted as a consequence of decreased diffusion of protein radicals within the protein network. Both protein cross linking and fragmentation, are dose dependent processes, with fragmentation prevailing below 10-15 kGy, and cross linking prevailing at the radiation doses >15 kGy. The radiolytic behaviour of the thick fraction of egg white, suggests that gamma irradiation of similar mucine containing structures might also result in accumulation of structurally altered and conceivably non-functional proteins in vivo.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Stress effects on the phosphorylation of c-jun-nterminal kinases and on nuclear translocation of hsp70 in rat hippocampus

Glucocorticoids have diverse effects in cellular processes in hippocampus (HIPPO) under stress. Beside genomic pathways, their effects are also mediated by direct activation of subfamily of mitogen-activated protein kinases termed, c-Jun-Nterminal kinases (JNKs). We analysed the phosphorylation status of cytoplasmic and nuclear JNK isoforms, and expression of its inhibitor Hsp70 protein in HIPPO of rats exposed to diverse types of stress. Activity of JNK1 in cytoplasm and nucleus was decreased in all types of stress, while the activity of cytoplasmic JNK2/3 was markedly higher in acute stress, and unaltered or lowered in chronic and combined stress. Hsp70 was significantly decreased in cytoplasm and increased in nucleus under all stress conditions indicating its cytoplasmic-nuclear translocation.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Corticosterone level alters optimal heat shock protein 90/glucocorticoid receptor ratio in hippocampus of stressed rats

Hippocampus (HIPPO) is one of the key brain structures, rich in glucocorticoid receptor (GR), a transcriptional factor involved in negative feedback of hypothalamic- pituitary-adrenal (HPA) axis in response to stress. Heat shock proteins accompany GR maintaining its optimal conformation, ligand binding ability and translocation to the nucleus. In order to evaluate the expression of GR, Hsp90 and their ratio we exploited three diverse types of stress (acute immobilization, chronic isolation and combination of the two). Our results indicated the same pattern of expression and compartmental distribution for both proteins, as well as for their ratio, under acute and combined stress when the level of corticosterone (CORT) was high. On the contrary, when CORT was low, such as in chronic stress, Hsp90/GR ratio exhibited opposite pattern of expression and GR was not translocated to the nucleus.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Redox-sensitive transcription factor NFkB in brain of stressed wistar rats

Neuroendocrine stress (NES) causes stress-hormones increase and alters balance of intracellular reactive oxygen species (ROS) leading to vulnerability of brain neurons. Prolonged alterations of cell redox milieux may also lead to altered expression of redox sensitive transcription factors, such as NFκB, resposible for brain cell protection. In the presented study NFκB p65 (NFκB) levels were determined in hippocampus and brain cortex of Wistar male rats.exposed to stress of different duration The cytosolic NFκB level was unchanged in acute stress (A, 2h), but significantly down-regulated in either chronic (C,21-day) or combined (C+A) stress. The depletion of NFκB from cell cytosol probably reflected its nuclear translocation and decoupling from the repressive action of glucocorticoid receptor. Through initially protective, NFkB overactivity may lead to accumulation of toxic H2O2 and compromise brain cell capacity to restore homeostasis.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Effect of different types of stress on adrenal gland parameters and adrenal hormones in the blood serum of male Wistar rats

In the present study, we examined gross changes in the mass of whole adrenal glands and that of the adrenal cortex and medulla in mature male Wistar rats subjected to three different stress types: acute, chronic, and combined, i.e., chronic followed by acute stress. These parameters were correlated with adrenal activity as judged from serum levels of corticosterone and catecholamine, respectively, as well as with serum levels of ACTH and glucose. Under all three conditions, we observed bilaterally asymmetric and stress-type-independent hypertrophy of whole adrenals, as well as adrenal cortices and medullas. Under acute and combined stress, adrenal hypertrophy was followed by increase of adrenal hormones in the blood serum. However, under chronic stress, both cortical and medullar activities as judged from low or unaltered levels of the respective hormones and glucose were compromised and disconnected from the input signal of ACTH. Since all of the studied adrenal activities could be restored by subsequent acute stress, it is concluded that chronic isolation can be viewed as partly maladaptive stress with characteristics resembling stress resistance rather than the stress exhaustion stage of the general adaptation syndrome

Adjuvant antiproliferative and cytotoxic effect of aloin in irradiated HeLaS3 cells

Naturally occurring phytoanthracycline, aloin, was used to radiosensitize HeLaS3 human cervix carcinoma cells. The results indicated that the cytotoxic adjuvant effect of aloin was synergistic with IR at all drug concentrations and comparable to the cytotoxicity of 5-10Gy IR alone. Radiosensitization of HeLaS3 cells was achieved by 60µM aloin which reduced IC50 dose of IR from 3.4- to 2Gy. The cell damage by both agents compromised cell capacity to conduct programmed cell death by apoptosis, and led to the synergic cytotoxic cell death by necrosis.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Antioxidant enzymes expression in liver of stressed wistar rat

The antioxidant enzymes (AOEs) expression was studied in Wistar rat liver under two types of stress: acute (immobilization) and chronic (isolation). The acute stress induced increase in blood corticosterone (CORT) and glucose (GLU), but decreased AOEs expression, and such conditions may result in oxidative stress. In contrast to acute stress, in chronic stress conditions, when both CORT and GLU were low, the AOEs expression was markedly induced. This increase in MnSOD, CuZnSOD, and catalase exhibited similar trend implying efficient detoxification of O2 .- and H2O2.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Superoxide dismutases in radioresistant PC-3 human prostate carcinoma cells

The molecular mechanism of gamma-ionizing radiation (IR) resistance of human prostate cancer cells PC-3 is not known. Since low-LET-IR effects are primarily achieved through generation of reactive oxygen species (ROS), IR-induced expression of ROSmetabolizing antioxidant enzymes, Mn- and CuZn-superoxide dismutase (Mn- and CuZnSOD) and catalase (CAT), and their upstream regulator transcription factor NFκB was followed. Significant elevation of both SODs was found in cells irradiated with 10- and 20 Gy, while CAT and NFkB expression was unchanged. Since, such conditions lead to accumulation of H2O2, it is concluded that radioresistance of PC-3 cells may emerge from positive feed-forward vicious circle established between H2O2 activation of NFκB and elevated MnSOD activity.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200