Peroxynitrite

TROKE is the third main cause of death after heart disease and cancer and the leading cause of chronic disability. It occurs as a result of the loss of blood supply or inadequate blood flow. The pathophysiological mechanisms leading to the neurological injury from stroke are complex, and a single neuroprotective approach has never been shown to be sufficient in alleviating stroke casualty. 14,15,21 Ischemic stroke triggers the cascade of events leading to excessive release of excitatory amino acid, calcium overload , generation of ROS, and alterations in gene expression. 10,20 The involvement of ROS such as superoxide, hydrogen peroxide, hydroxyl radical, and peroxynitrite has been postulated in IR injury. 1,30,34 In biological conditions, peroxynitrite is formed very rapidly from the reaction of NO with superoxide anion. Analysis of recent data indicates that most of the toxic effects of NO as well as superox-ide radicals are attributed to peroxynitrite. More specifically , peroxynitrite can cause cell membrane destruction by inducing lipid peroxidation, hydroxylation and nitration of the aromatic residues of amino acids and nucleotides, and single-and/or double-strand breaks in DNA. 3,24,26 The DNA strand breaks lead to the activation of the DNA repair enzyme, PARP, which uses NAD as a substrate. Massive DNA damage mediated by IR injury results in excessive PARP activation, leading to depletion of its substrate NAD and subsequently ATP and eventually to cell death. 13 From the aforementioned evidence one can infer the involvement of the peroxynitrite–PARP cascade in IR injury, and thus pharmacological interventions targeted at this cascade might be effective in treating cerebral IR injury. Peroxynitrite scavengers (melatonin) 14,15,21 and PARP inhibitors (3-aminobenzamide, nicotinamide, and PJ 37) 40 have been shown to be protective in an IR injury model. Previously, we demonstrated the neuroprotective effect of an antiox-Object. The authors evaluated the neuroprotective effect of 5,10,15,20-tetrakis(N-methyl-4-pyridyl)porphyrinato-iron(III) (FeTMPyP), a peroxynitrite decomposition catalyst, and 1,5-isoquinolinediol (ISO), a poly(adenosine diphos-phate [ADP]-ribose) polymerase (PARP) inhibitor, alone and in combination in rats with focal cerebral ischemia induced by middle cerebral artery occlusion (MCAO). Methods. Male Sprague–Dawley rats were subjected to 2 hours of MCAO followed by 22 hours of reperfusion. Cerebral infarction and neurological deficits were estimated after ischemia. Intraperitoneal injections of FeTMPyP (1 and 2 mg/kg) and ISO (0.05 and 0.1 mg/kg) were administered alone or in combination in ischemic animals. The PARP activity in vehicle-and drug-treated groups was estimated using anti–poly(ADP-ribose) antibody in immunofluores-cence and immunoblotting studies. Two hours of MCAO and 22 hours of reperfusion produced significant cerebral infarction and neurological deficits. Treatment with FeTMPyP (1 and 2 mg/kg) and ISO (0.05 and 0.1 mg/kg) produced a significant reduction in cerebral infarction and neurological deficits. Combination therapy (2 mg/kg FeTMPyP and 0.1 mg/kg ISO) enhanced the inhibition of ischemic volume (77.81 0.86%) compared with monotherapies (FeTMPyP 54.07 5.6% and ISO 53.06 3.88%). Immunoblotting and immunofluorescence studies showed PARP activation after ischemia, which was reduced by drug treatment. Conclusions. Neuroprotection observed with FeTMPyP and ISO alone and in combination may be attributed to inhibition of the peroxynitrite–PARP cascade of cerebral ischemia/reperfusion injury. KEY WORDS • focal cerebral ischemia • peroxynitrite decomposition catalyst • poly(adenosine diphosphate–ribose) polymerase • neuroprotection S 669 Abbreviations used in this paper: ANOVA = analysis of variance; DMSO = dimethyl sulfoxide; ECA = external carotid artery; FeTMPyP = 5,10,15,20-tetrakis(N-methyl-4-pyridyl)porphyrinato-iron(III); FITC = fluorescein isothiocyanate; IgG = immunoglobulin G; IR = ischemia/reperfusion; ISO = 1,5-isoquinolinediol; MCAO = middle cerebral artery occlusion; NAD = nicotinamide adenine di-nucleotide; NIPER = National Institute of Pharmaceutical Education and Research; NO = nitric oxide; NOS = NO synthase; PAR = poly(adenosine diphosphate–ribose); PARP = PAR polymerase; PBS = phosphate-buffered saline; ROS = reactive oxygen species; TBS = Tris-buffered saline; TTC = triphenyltetrazolium chloride.

Vegetable oil is readily available and inexpensive,  can be used to synthesize various types of polymers. In our present study, epoxidized punnal oil has been synthesized from punnal oil via peroxyacetic acid generated ‘in situ by treating acetic acid with hydrogen peroxide as an oxygen donor. The epoxidation is catalyzed by using sulphuric acid. The epoxidation is confirmed by iodine value, oxirane oxygen analysis, Fourier transform infrared spectroscopy  (FT-IR),  nuclear magnetic resonance  (NMR), and thin-layer chromatography  (TLC)  analysis. Natural fibers such as jute,  sisal,  banana,  rice husk, etc are locally available in abundance and have excellent physical and mechanical properties, and can be used more effectively in the development of composite materials for various applications.  Epoxy composite samples are prepared from the natural fiber with different ratios using triethylamine hardener and phthalic anhydride. The mechanical properties viz. tensile strength and the physical properties observed are discussed in detail.

Nitrarea este o modificare poasttranslationalacare modifica activitateaenzimatica (nitrarea NO sintazei cu effect autoreglator sau in citeva cazurti amplifica activitatea functional (fibrinogenul nitrat).
Mai putin investigate este agragarea indusa de peroxynitrit la nivelul tirozinei (punti ditirozinicde) si fenomenele molecular si celulare declansate de aceasta in plasma sanguine (modificarea activitatii molecule respectivecum este imunoglobulina G) sau acumularea de polimeri fibrilari(synucleinele din corpii neuronali LEWY.

Ne propunem sa investigam posxibila agragare a proteinelor plasmatice si a leucocitelor din plasma sanguine dupa administrarea unir protein nitraret extracorporeal in dispositive chimice special.
Nitrare aovalbuminei s a facut proin reactia xantoproteica iar pH ul a fost reglatla valoarea 9.
Sistemul biologic utiulizatr pentru acest studio a fost reprezentat de reteaua microvasculara mezenterica a broastei mascule Bufo Bufo, monitorizata prin microscopie intravitala. Videocamera SONY TRV 253 a fost conectata la un microscop de laborator standard si imaginile in formatul MPEG au fostn trimise mla PC Pentium FUJITSU SIEMENS iar analiza de imagine s a efectuat off line.

Nitric oxide (NO°) is now recognised as one of the most important molecules influencing the development, progression and treatment of cancer. A key component of its action is as a negative and positive regulator of apoptosis. Broadly, constitutive levels of NO° (nM), are capable of inhibiting numerous signalling pathways in both normal and cancer cells. These include soluble guanylate cyclase, leading to reduced Ca++ signalling, inhibition of caspases and scavenging of reactive oxygen species, all of which promote survival signalling. High concentrations (μM-mM) on the other hand, generally promote apoptosis. Pathways involving cGMP, cytochrome c release, mitogen activated kinases, ceramide and poly(ADP)ribose polymerase have all been implicated. The role of p53 in NO°-induced cell death has been widely studied. In many cell types p53-dependent signalling is involved, while in others, apoptosis occurs in the absence of functional p53. There is also evidence that the tumour microenvironment, where low oxygen and glucose levels prevail, enhances cell death signalling by NO° and peroxynitrite, thus tumours may be more sensitive to high levels of NO° than their normal tissue counterpart. The cytotoxicity of NO° has been studied directly in many tumour models, both in vitro and in vivo. In all cases, high concentrations of NO°, generated by donor drugs or by iNOS gene transfer caused extensive tumour cell death, which was enhanced by the ability of NO° to diffuse readily from its source of generation to most cells within tumours. NO° was also a very effective enhancer of conventional chemo- and radiotherapy. Thus, NO° therapy has great potential to improve the treatment of cancer.

Peroxynitrite (ONOO−) is a potent oxidizing agent generated by the interaction of nitric oxide (NO) and the superoxide anion. In physiological solution, ONOO− rapidly decomposes to a hydroxyl radical, one of the most reactive free radicals, and nitrogen dioxide, another species able to cause oxidative damage. In the present study we investigated the effect of ONOO− on the expression of haem oxygenase-1 (HO-1), an inducible protein that is highly up-regulated by oxidative stress. Exposure of bovine aortic endothelial cells to ONOO− (250±1000 µM) produced a concentration-dependent increase in haem oxygenase activity and HO-1 protein expression. This effect was completely abolished by the ONOO− scavengers uric acid and N-acetylcysteine, and partly attenuated by 1,3-dimethyl-2-thiourea, a scavenger of hydroxyl radicals. ONOO− also produced a concentration-dependent increase in apoptosis and cytotoxicity, which were considerably decreased by uric acid and N-acetylcysteine. A 70%decrease in apoptosis was observed when cells were exposed to ONOO− in the presence of 10 µM tin protoporphyrin IX (SnPPIX), an inhibitor of haem oxygenase activity. When SnPPIX was added 5 min after ONOO−, apoptosis decreased by only 40%, which suggests that an interaction between ONOO− and the protoporphyrin occurs in our system. Increased haem oxygenase activity by pretreatment of cells with haemin resulted in elevated bilirubin production and was associated with a substantial decrease (35%) in ONOO−-mediated apoptosis. These results indicate the ability of ONOO− to modulate the expression of the stress protein HO-1 and suggest that the haem oxygenase pathway contributes to protection against the cytotoxic action of ONOO−.