The cyclooxygenase hydroperoxide product PGG(2) activates synaptic nitric oxide synthase: a possible antioxidant response to membrane lipid peroxidation

Antioxidants as Molecular Probes: Structurally Novel Dihydro-m-Terphenyls as Turn-On Fluorescence Chemodosimeters for Biologically Relevant Oxidants

One interesting aspect of antioxidant organic molecules is their use as probes for the detection and quantitation of biologically relevant reactive oxidant species (ROS). In this context, a small library of dihydroterphenyl derivatives has been synthesised and studied as fluorescent chemodosimeters for detecting reactive oxygen species and hypochlorite. The fluorescence quantum yields of these molecules are negligible, while the corresponding aromatized compounds formed upon oxidation show moderate to high native fluorescence, depending on their structures. The fluorescence signal is quickly developed in the presence of trace amounts of the probe and the analytes in acetonitrile media at room temperature, with good analytical figures. ROS detection in aqueous media required incubation at 37 °C in the presence of horseradish peroxidase, and was applied to glucose quantitation by coupling glucose oxidation by O₂ to fluorescence detection of H₂O₂. The mild reaction conditions and sensitive fluorescent response lead us to propose dihydroterphenyls with an embedded anthranilate moiety as chemosensors/chemodosimeters for ROS detection.

Photo-infrared pulsed bio-modulation (PIPBM): a novel mechanism for the enhancement of physiologically reparative responses

OBJECTIVE

The present manuscript describes the non-invasive, long-range, energy transport of a singular infrared pulsed laser device (IPLD) and the upstream components of the original action mechanism, designated photo-infrared pulsed bio-modulation (PIPBM).

BACKGROUND DATA

Major strides have been taken in recent years towards scientifically acceptable clinical applications of low-energy lasers. Nevertheless, challenges still abound. For instance, the range of potential target tissues for laser therapy in medicine has been, until now, limited by the optical penetration of the beam or to sites accessible by fiberoptics. In addition, much needs to be learned about the action mechanisms of pulsed lasers, which can induce unique biological effects.

METHODS

We present a review of the IPLD laser technology and the PIPBM mechanism.

RESULTS

The studies reviewed suggest that the PIPBM enhances physiologically reparative processes in a non-toxic and selective manner through the activation and modulation of chaotic dynamics in water. These, in turn, lead not only to local, but also long-distance (systemic) effects.

CONCLUSIONS

Though additional studies are necessary to fully explore the biological effects of the PIPBM induced by the IPLD, this mechanism may have multiple potential applications in medicine that are the subject of active current and future investigations.

Age-promoted creation of a pro-cancer microenvironment by inflammation: pathogenesis of dyscoordinated feedback control

Aging and local chronic inflammation are established risk factors for epithelial tumorigenesis. These risk factors can act individually and/or synergistically to increase the incidence of age-related carcinomas. The basis for this co-stimulatory response has not yet been defined, nor have the feedback mechanisms that are responsible for this synergism. This review provides insight into the age-stimulated dysregulation of coordination of feedbacks in oxygen-, heme-, and proteolysis-dependent metabolic pathways caused by acute and chronic inflammation, and its role as a possible pathological basis for the creation of a pro-cancer microenvironment (PCM). The PCM facilitates the selective survival and growth of transformed cells (in a manner similar to a cancer-supportive microenvironment (CM)). The cancer-induced environment has certain features in common with chronic inflammatory-induced PCM. Namely, there are: enhanced oxidative cell resistance against apoptosis, increased production of matrix-degrading enzymes, switching to glycolytic metabolism, angiogenesis and vasorelaxation thus providing nutrient delivery, but restriction of the immune cell mobilization and/or its activation. The hypothetical model of PCM-genesis is presented as a result of enzymatic dysregulation of feedback control including oxygen-, heme-, prostaglandin E(2)-, metalloproteinase-9-, and NO/CO-dependent pathways. PCM-genesis takes place between the growth-inhibiting (cytotoxic) and growth promoting (regenerative) stages of inflammatory response. According to this model, age-related metabolic changes create opportunities for chronic (not acute) inflammatory response, which supports the PCM-condition with the non-healing wound state that often occurs around carcinomas.

Bimodal induction of dopamine-mediated striatal neurotoxicity is mediated through both activation of D1 dopamine receptors and autoxidation

Striatal neurodegeneration occurs through unknown mechanisms in certain neurodegenerative disorders characterized by increased and sustained synaptic levels of dopamine (DA). Treatment of rat primary striatal neurons with DA causes profound neurotoxicity, with increased production of free radicals and accelerated neuronal death. DA effects were partly reduced by the antioxidant sodium metabisulfite (SMBS), and the D1 DA receptor antagonist, SCH 23390, and were completely blocked upon co-treatment with SMBS and SCH 23390. Part of DA effects were mimicked by either H(2)O(2), or by the D1 agonist, SKF R-38393, indicating the existence of two distinct signaling pathways through which the neurotoxicity of DA is manifest. DA effects did not proceed through D2-like DA or beta-adrenergic receptor signaling pathways. The D1 receptor-mediated and the autoxidative pathways of DA neurotoxicity converge to cause activation and/or increased synthesis of neuronal and inducible, but not endothelial, nitric oxide synthase (NOS). The reduction of DA striatal neurotoxicity through blockade of D1 DA receptors, suggests novel therapeutic approaches in the management of striatal neurodegeneration.

Acrolein-induced vasomotor responses of rat aorta

Acrolein is a highly reactive aldehyde pollutant and an endogenous product of lipid peroxidation. Increased generation of, or exposures to, acrolein incites pulmonary and vascular injury. The effects of acrolein on the vasomotor responses of rat aortic rings were studied to understand its mechanism of action. Incubation with acrolein (10-100 microM) alone did not affect the resting tone of aortic vessels; however, a dose-dependent relaxation of phenylephrine-precontracted aortic rings was observed. Acrolein-induced relaxation was slow and time dependent and the extent of relaxation after 100 min of application was 44.7 +/- 4.1% (10 microM), 56.0 +/- 5.6% (20 microM), 61.0 +/- 7.9% (40 microM), and 96.1 +/- 2.1 (80 microM), respectively, versus 14.2 +/- 3.3% relaxation in the absence of acrolein. Acrolein-induced vasorelaxation was prevented by endothelial denudation and was abolished on pretreatment with the nitric oxide synthase inhibitor Nomega-nitro-L-arginine methyl ester, the guanylyl cyclase inhibitor 1H-[1,2,4]oxidazolo[4,3-a]quinoxaline-1-one, or the cyclooxygenase inhibitor indomethacin. Inhibition of K+ channels (by tetrabutylammonium) or Na+-K+-ATPase (by ouabain) did not significantly prevent acrolein-mediated vasorelaxation. Exposure to acrolein in the presence or absence of other compounds elicited slow wave vasomotor effect in 77% of aortic vessels versus 1.4% in control. Vasomotor responses were also studied on aortic rings prepared from rats fed 2 mg. kg-1. day-1 acrolein for 3 alternate days by oral gavage. These vessels developed a significantly lower contractile response to phenylephrine compared with controls. Together, these results indicate that acute acrolein exposure evokes delayed vasorelaxation due to a nitric oxide- and prostacyclin-dependent mechanism, whereas in vivo acrolein exposure compromises vessel contractility.

Superoxide activates constitutive nitric oxide synthase in a brain particulate fraction

Nitric oxide (*NO) can act as an antioxidant by directly scavenging reactive free radicals, inhibiting the oxidative chemistry of iron, and signaling the up-regulation of antioxidant enzymes. However, the cellular utility of *NO as an antioxidant requires that constitutive nitric oxide synthase (NOS) be activated rapidly by a signal(s) for oxidant formation. We report here that superoxide (O2*-), added directly as potassium superoxide (KO2), produced a superoxide dismutase-sensitive and hydrogen peroxide-independent stimulation of NOS activity, measured by the conversion of [3H]arginine to [3H]citrulline and nitrite formation, in a synaptic particulate fraction from rat brain cerebral cortex. O2*- produced maximal activation of NOS in the presence of the antioxidant urate and ATP. Stimulation of NOS activity by O2*- was abolished by N-monomethyl-L-arginine and by the Ca2+ chelator EGTA but not by 7-nitroindazole, which would be expected to inhibit neuronal NOS. We propose that limited activation of NOS by O2*- may be an important contributor to brain oxidant defenses and, more generally, a signal for cellular adaptation and survival, although excessive generation of nitrogen oxides would be expected to produce neurotoxicity.