Effects of metal ions on ecto-ATPase activity in plasma membrane isolated from the rat ovary

Effects of increasing concentrations of metal salts SrCl2, CsCl, CrCl3, CdCl2, and HgCl2 on rat ovarian plasma membrane ecto-ATPase activity were investigated. CrCl3, CdCl2, and HgCl2 exert total inhibition of enzyme activity in the presence of 0.01 M and 0.1 M respectively. SrCl2 and CsCl exhibit up to 25% of inhibition. According to the IC50, ecto-ATPase possesses greater sensibility to Cd2+ (IC50 is 0.887 mM) > Cr3+ (IC50 is 1.936 mM) > Hg2+ (IC50 is 4.39 mM). All investigated ions exert negative cooperativity (n<1). Physico-chemical properties of the metal are of importance in metal toxicity. Cr3+ and Cd2+ ions, with lower radius may inhibit ecto-ATPase activity by binding to hydrolytic site or by replacing Mg2+ in Mg-ATP, a substrate of the enzyme. Hg2+, as a larger ion probably inhibits the enzyme activity through conformational changing the enzyme by binding to S-S or -SH groups on the site distinct to hydrolytic one. By inhibiting the enzyme activity these metals may affect maturation and release of oocytes as well as synthesis and release of gonadal hormones and decrease the fertility of mammalsPhysical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Modulation of Ca2+ ion flux through mitochondrial membrane of the rat brain steam synaptosomes by 17β-estradiol

In the present study the modulation of Ca2+ ion flux in the synaptosomal mitochondria isolated from the ovariectyomized rat Brain Steam and the possible roll of membrane bound estradiol was examined. Physiological concentrations of 17β-estradiol binds specifically to isolated mitochondria (Vmax 3.37± 0.25 pmol/mg protein, Km 1.85± 0.06 nmol/l of free estradiol). Addition of 17β-estradiol (10 pmol/l - 1 nmol/ l) in vitro decreased mitochondrial calcium ion efflux significantly (25%) after 10 minutes. Modulation of calcium ion efflux and mitochondrial ion retention may be the way that 17β-estradiol (E2) exerts its role in the nerve cell homeostasis.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Effect of EDTA on the inhibition of rat myometrial ecto-atpase activity in the presence of heavy metal ions I. Mercury

The effects of increasing concentrations of HgCl2 on rat uterine plasma membrane ecto-ATPase activity, in presence and absence of ethylenediamine tetra acetic acid (EDTA) were studied. The aim was to examine the ability of EDTA to prevent mercury induced inhibition of ecto-ATPase activity. Our results show that addition of 1mmol/l EDTA to the reaction mixture potentiates Hg2+ induced inhibition of enzyme activity. We may concluded that formation of the HgEDTA complex increased capacity of Hg2+ to inhibit enzyme activity.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Protection of copper ions induced inhibition of rat myometrial ecto-atpase activity by edta

The potential protective effects of ethylenediamine tetraacetic acid (EDTA) on the CuSO4 cell toxicity was examined on rat myometrial plasma membranes. Activity of plasma membrane ecto-ATPase, as modulator of purinergic signaling in the presence of increasing concentrations of copper salt and in the presence or absence of EDTA was studied. Our results show that 1mmol/l EDTA may exert protective effects on Cu2+-induced toxicity by increasing half-maximum inhibitory activities of this ion.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Early effects of ionizing ir-radiation on the ecto- 5'nucleotidase activity in rat brain during postnatal development

In the present study, early effects of low (50 cGy) and therapeutic dose (2 Gy) of ionizing γ-irradiation on ecto-5’nucleotidase activity in rat brain neuronal cells during postnatal development were studied. Ecto-5’-nucleotidase is the major enzyme that hydrolyzes extracellular AMP and is responsible for the formation of the P1 receptor agonist-adenosine. It was shown that the levels of AMP hydrolyses by the enzyme were not affected by irradiation in the rats during first 4 postnatal weeks. A both low- and therapeutic dose significantly decreased hydrolyses of extracellular AMP in pubertal and adult rats by 10-14%. These findings indicate that low dose exerts the same effects on ecto-5'nucleotidase activity as therapeutic one in first hour after irradiation. Another findings is that in early postnatal development, brain ecto-5'nucleotidase was resistant to irradiation damage.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Properties of grape seed Proanthocyanidins and quercetin in human lymphocytes

This study addresses the in vitro protective effects of proanthocyanidins and quercetin on the frequency of micronuclei with reference to the antioxidant status of cultured human lymphocytes also subjected to 2 Gy of gamma-radiation. Treatment of lymphocytes with proanthocyanidins induced a significant decrease in the frequency of micronuclei and reduction of malonyldialdehyde production, as well as increased catalase and glutathione S-transferase activity Quercetin induces a higher incidence of micronuclei and production of malonyldialdehyde. The seven-fold increase of micronuclei frequency induced by a therapeutic dose of gamma-radiation was decreased in the presence of proanthocyanidins. These results demonstrate that proanthocyanidins may be important in the prevention of ROS-induced oxidative lymphocyte damage by decreasing DNA damage, lowering membrane lipid peroxidation, and increasing the activity AOP enzymes, as well as by reducing the level of gamma-radiation-induced DNA damage. Our results support the potential benefits of proanthocyanidins as efficient antioxidants and radioprotectors

Different sensibility of ecto-ATPase from brain and ovary to Cu2+ and Zn2+

Ions of zinc and cooper represents micro elements present in all organisms but they can be accumulated in various tissues from the environment by food or pollution. In this work we examined the effects of chloride salts of Cu2+ and Zn2+ on the activity of ecto-ATPase, integral plasma membrane protein, in brain and ovarian cells. Both ions exhibit similar effects on brain or ovarian enzyme activity. Cooper in brain and ovary totally inhibits enzyme activity at the concentration of 1 mM and 0.1 M respectively. IC50 for brain is 36 µM while in ovary it is 192 µM. Zinc inhibits in both tissues 50% of the control enzyme activity at concentrations of 1 mM in brain and 0.1 M in ovary with IC50 of 1mM and 14 mM respectively. These metals possess an affinity for -SH groups in the enzyme protein, may replace Mg2+ in enzyme substrate, MgATP or to bind for enzyme substrate site. According to the total inhibition of ecto-ATPase activity by Cu 2+, it may be proposed that its site of action is on the substrate or substrate binding site, while Zn2+ modulates enzyme activity by acting on the –SH or S-S groups of the enzyme. Inhibiting or decreasing ecto-ATPase activity in brain and ovary, these two metal ions may be toxic and seriously disturb the proper functioning of the investigated tissues.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Effect of EDTA on the inhibition of rat myometrial ecto-ATPase activity in the presence of heavy metal ions II. cadmium

The effects of ethylenediamine tetraacetic acid (EDTA) on the CdCl2 cell toxicity was examined on rat myometrium. Activity of plasma membrane ecto-ATPase, as modulator of purinergic signaling in the presence of increasing concentrations of cadmium salt and in the presence or absence of EDTA were studied. The EDTA, chelating cadmium ions decrease inhibitory cadmium potency by increasing half-maximum inhibitory activities of this ion.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Low-dose ionizing irradiation affects ntpdase activity in neuoronal cells of young female rats

In the present study, time-dependent effects of low-dose ionizing irradiation on membrane-bound enzyme activity in neuronal cell endings of young female rat brains were sudied. The ecto-adenosine triphospho diphosphohydrolases (NTPDases) hydrolyse the extracellular nucleotide di- and tri- phosphates (ADP and ATP) in the presence of divalent cations (Ca2+ and Mg2+). The influence of whole-body irradiation on membrane enzymes ATP and ADP hydrolysing activity were monitored 1, 24 and 72 h after irradiation. Animals were divided into three groups: non-treated, under physiological conditions (C), immobilized and whole body irradiated with 50 cGy by γ-rays (R) and immobilized non-irradiated (I) animals. It was shown that the levels of ATP and ADP hydrolyses were not affected within 72h after immobilisation. Lowdose irradiation significantly decreased hydrolyses of extracellular ATP as early as 1h after irradiation. ADP hydrolyses within 72 h and ATP hydrolysis after 24 h were not altered.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Efficiency analysis of higher education in Croatia

Kvalitetna organizacija sustava obrazovanja sve je veći faktor u ostvarivanju kontinuiranog napredovanja gospodarstva. Upravo zbog toga je važno mjeriti kvalitetu obrazovanja kroz brojne pokazatelje učinkovitosti. Jedan od pokazatelja kvalitete visokog obrazovanja je i praćenje kretanja broja upisanih i završenih studenata na visokim učilištima koji jasno prikazuje povećava li se ili smanjuje broj studenata koji upisuju odnosno završavaju studije. U posljednjih nekoliko godina Hrvatska sve više ulaže u povećanje kvalitete visokog obrazovanja, djelomično kroz primjenu Bolonjskog procesa, a djelomično kroz interne analize samih ustanova visokog obrazovanja. Ulaganje u kvalitetu rezultiralo je pozitivnim stopama završavanja studija no unatoč tome, Hrvatska i dalje zaostaje za Europom prema udjelu visokoobrazovanih. Analiza učinkovitosti visokog obrazovanja pokazuje da Hrvatska kontinuirano povećava svoj udio visokoobrazovanih no da bi se dosegao prosjek Europske Unije, daljnji napori u poboljšanju obrazovne slike Republike Hrvatske i dalje predstavljaju nužnost.Quality organization of the education system is a growing factor in achieving continuous economic progress. Therefore it is important to measure quality of education through a number of indicators of effectiveness. One of the indicators of quality of higher education is also to monitor changes in the number of enrolled and graduated students at higher education institutions that clearly shows whether the number of students who enroll and complete their studies increases or decreases. In a last few years Croatia is investing in increasing quality of higher education, partly through implementation of Bologna process, and partly through internal analysis of institutions of higher education. Investing in quality resulted with positive completion rate but despite that, Croatia is still behind Europe according to the share of highly educated. Efficiency analysis of higher education shows that Croatia is continuously increasing its share of highly educated but in order to reach the average of European Union, further efforts in improving educational image still represent a necessity