Cellular metabolism of substance P produces neurokinin-1 receptor peptide agonists with diminished cyclic AMP signaling.

Substance P (SP) is released from sensory nerves in the arteries and heart. It activates neurokinin-1 receptors (NK1Rs) causing vasodilation, immune modulation, and adverse cardiac remodeling. The hypothesis was tested: SP and SP metabolites activate different second messenger signaling pathways.

Slow-Release Nitrogen Fertilizers with Biodegradable Poly(3-hydroxybutyrate) Coating: Their Effect on the Growth of Maize and the Dynamics of N Release in Soil.

Fertilizers play an essential role in agriculture due to the rising food demand. However, high input fertilizer concentration and the non-controlled leaching of nutrients cause an unwanted increase in reactive, unassimilated nitrogen and induce environmental pollution. This paper investigates the preparation and properties of slow-release fertilizer with fully biodegradable poly(3-hydroxybutyrate) coating that releases nitrogen gradually and is not a pollutant for soil.

Macrophage 12(S)-HETE Enhances Angiotensin II-Induced Contraction by a BLT2 (Leukotriene B Type-2 Receptor) and TP (Thromboxane Receptor)-Mediated Mechanism in Murine Arteries.

12/15-LO (12/15-lipoxygenase), encoded by gene, metabolizes arachidonic acid to 12(S)-HETE (12-hydroxyeicosatetraenoic acid). Macrophages are the major source of 12/15-LO among immune cells, and 12/15-LO plays a crucial role in development of hypertension. Global - or macrophage-deficient mice are resistant to Ang II (angiotensin II)-induced hypertension.

Deactivation of 12(S)-HETE through (ω-1)-hydroxylation and β-oxidation in alternatively activated macrophages.

Polarization of macrophages to proinflammatory M1 and to antiinflammatory alternatively activated M2 states has physiological implications in the development of experimental hypertension and other pathological conditions. 12/15-Lipoxygenase (12/15-LO) and its enzymatic products 12(S)- and 15(S)-hydroxyeicosatetraenoic acid (HETE) are essential in the process since disruption of the gene encoding 12/15-LO renders the mice unsusceptible to hypertension. The objective was to test the hypothesis that M2 macrophages catabolize 12(S)-HETE into products that are incapable of promoting vasoconstriction.

Effect of Angiotensin II and ACTH on Adrenal Blood Flow in the Male Rat Adrenal Gland In Vivo.

Angiotensin II (Ang II) and adrenocorticotropic hormone (ACTH) regulate adrenal vascular tone in vitro through endothelial and zona glomerulosa cell-derived mediators. The role of these mediators in regulating adrenal blood flow (ABF) and mean arterial pressure (MAP) was examined in anesthetized rats. Ang II (0.

Vascular hepoxilin and trioxilins mediate vasorelaxation through TP receptor inhibition in mouse arteries.

Aim: 12/15-lipoxygenase (12/15-LO) metabolizes arachidonic acid (AA) into several vasoactive eicosanoids. In mouse arteries, we previously characterized the enzyme's 15-LO metabolites 12(S)-hydroxyeicosatetraenoic acid (HETE), 15-HETE, hydroxyepoxyeicosatrienoic acids (HEETAs) and 11,12,15-trihydroxyeicosatrienoic acids (11,12,15-THETAs) as endothelium-derived relaxing factors. However, the observed 12-LO metabolites remained uncharacterized.

Products of lipid peroxidation, but not membrane susceptibility to oxidative damage, are conserved in skeletal muscle following temperature acclimation.

Changes in oxidative capacities and phospholipid remodeling accompany temperature acclimation in ectothermic animals. Both responses may alter redox status and membrane susceptibility to lipid peroxidation (LPO). We tested the hypothesis that phospholipid remodeling is sufficient to offset temperature-driven rates of LPO and, thus, membrane susceptibility to LPO is conserved.

Binding and cytotoxic trafficking of cholesterol hydroperoxides by sterol carrier protein-2.

Redox-active cholesterol hydroperoxides (ChOOHs) generated by oxidative stress in eukaryotic cells may propagate cytotoxic membrane damage by undergoing one-electron reduction or, at low levels, act as mobile signaling molecules like H2O2. We discovered that ChOOHs can spontaneously translocate between membranes or membranes and lipoproteins in model systems, and that this can be accelerated by sterol carrier protein-2 (SCP-2), a nonspecific lipid trafficking protein. We found that cells overexpressing SCP-2 were more susceptible to damage/toxicity by 7α-OOH (a free radical-generated ChOOH) than control cells, and that this correlated with 7α-OOH delivery to mitochondria.

Role of macrophage PPARγ in experimental hypertension.

Targeted disruption of the Alox15 gene makes mice resistant to angiotensin II-, DOCA/salt-, and N(ω)-nitro-L-arginine methyl ester (L-NAME)-induced experimental hypertension. Macrophages, a primary source of Alox15, are facilitating this resistance, but the underlying mechanism is not known. Because Alox15 metabolites are peroxisome proliferator-activated receptor (PPAR)γ agonists, we hypothesized that activation of macrophage PPARγ is the key step in Alox15 mediation of hypertension.

Effect of human 15-lipoxygenase-1 metabolites on vascular function in mouse mesenteric arteries and hearts.

Lipoxygenases regulate vascular function by metabolizing arachidonic acid (AA) to dilator eicosanoids. Previously, we showed that endothelium-targeted adenoviral vector-mediated gene transfer of the human 15-lipoxygenase-1 (h15-LO-1) enhances arterial relaxation through the production of vasodilatory hydroxyepoxyeicosatrienoic acid (HEETA) and trihydroxyeicosatrienoic acid (THETA) metabolites. To further define this function, a transgenic (Tg) mouse line that overexpresses h15-LO-1 was studied.

Mice lacking macrophage 12/15-lipoxygenase are resistant to experimental hypertension.

In mouse arteries, Alox15 [leukocyte-type 12/15-lipoxygenase (LO)] is assumed to regulate vascular function by metabolizing arachidonic acid (AA) to dilator eicosanoids that mediate the endothelium-dependent relaxations to AA and acetylcholine (ACh). We used Alox15(-/-) mice, made by targeted disruption of the Alox15 gene, to characterize its role in the regulation of blood pressure and vascular tone. Systolic blood pressures did not differ between wild-type (WT) and Alox15(-/-) mice between 8-12 wk of age, but Alox15(-/-) mice exhibited resistance toward both N(G)-nitro-L-arginine-methyl ester (L-NAME)- and deoxycorticosterone acetate (DOCA)/high-salt-induced hypertension.

Relationship between oxidizable fatty acid content and level of antioxidant glutathione peroxidases in marine fish.

Biological membranes can be protected from lipid peroxidation by antioxidant enzymes including catalase (CAT) and selenium-dependent glutathione peroxidases 1 and 4 (GPx1 and GPx4). Unlike GPx1, GPx4 can directly detoxify lipid hydroperoxides in membranes without prior action of phospholipase A(2). We hypothesized that (1) GPx4 is enhanced in species that contain elevated levels of highly oxidizable polyunsaturated fatty acids (PUFA) and (2) activities of antioxidant enzymes are prioritized to meet species-specific oxidative stresses.

Sterol carrier protein-2 (SCP-2) involvement in cholesterol hydroperoxide cytotoxicity as revealed by SCP-2 inhibitor effects.

Sterol carrier protein-2 (SCP-2) plays an important role in cholesterol trafficking and metabolism in mammalian cells. The purpose of this study was to determine whether SCP-2, under oxidative stress conditions, might also traffic hydroperoxides of cholesterol, thereby disseminating their cytotoxic effects. Two inhibitors, SCPI-1 and SCPI-3, known to block cholesterol binding by an insect SCP-2, were used to investigate this.

Novel enrichment of tumor cell transfectants expressing high levels of type 4 glutathione peroxidase using 7alpha-hydroperoxycholesterol as a selection agent.

A novel approach for selecting high expressing cells out of a general population that had been transfected with a construct encoding cytosolic type 4 glutathione peroxidase (GPx4) is reported. The approach is described for GPx4-null COH-BR1 breast tumor cells and is based on use of a highly specific GPx4 substrate, 7alpha-hydroperoxycholesterol (7alpha-OOH), as a selection agent. Cells recovering from a highly toxic dose of liposomal 7alpha-OOH were found to be substantially more resistant to a second 7alpha-OOH challenge than cells recovering from a less toxic dose, but were much less resistant to t-butyl hydroperoxide (t-BuOOH) or H2O2.

Phospholipase action of platelet-activating factor acetylhydrolase, but not paraoxonase-1, on long fatty acyl chain phospholipid hydroperoxides.

Phospholipid hydroperoxide (PLOOH) degrading activity of high density lipoprotein (HDL)-derived paraoxonase-1 (PON1) was investigated, using peroxidized 1-palmitoyl-2-oleoyl phosphatidylcholine (PCOOH) as substrate and high performance thin layer chromatography for quantitative peroxide analysis. Incubation of PCOOH with PON1 resulted in decay of the latter and reciprocal buildup of oleic acid hydroperoxide (OAOOH) at rates unaffected by GSH or other reductants. A serine esterase inhibitor blocked this activity and a recombinant PON1 was devoid of it, raising the possibility that the activity represents platelet-activating factor acetylhydrolase (PAF-AH), an esterase that co-purifies with PON1 from HDL.

Intracellular dissemination of peroxidative stress. Internalization, transport, and lethal targeting of a cholesterol hydroperoxide species by sterol carrier protein-2-overexpressing hepatoma cells.

Sterol carrier protein-2 (SCP-2) plays a crucial role in the trafficking and metabolism of cholesterol and other lipids in mammalian cells. Lipid hydroperoxides generated under oxidative stress conditions are relatively long-lived intermediates that damage cell membranes and play an important role in redox signaling. We hypothesized that SCP-2-facilitated translocation of lipid hydroperoxides in oxidatively stressed cells might enhance cytolethality if highly sensitive sites are targeted and detoxification capacity is insufficient.

Redox status of dogs with non-hodgkin lymphomas. An ESR study.

Free radical and antioxidant parameters in healthy dogs (n=10) and dogs with non-Hodgkin lymphomas (n=11) were measured in blood and lymph node tissue samples before chemotherapy. Enzymatic and other biochemical measurements were performed. We found that (i) free radical concentrations based on ESR spectra of tissues correlated with higher proliferative character; (ii) lymphoma cases showed an impaired antioxidant status; (iii) tumors with low oxidative burst capacity and higher reduced/oxidized glutathione ratio responded better to chemotherapy; and (iv) affected blood and lymph nodes were under strong oxidative stress.

A thin layer chromatographic method for determining the enzymatic activity of peroxidases catalyzing the two-electron reduction of lipid hydroperoxides.

Thiol-dependent peroxidases catalyzing the reductive detoxification of lipid hydroperoxides (LOOHs) are crucial antioxidant components of mammalian cells. There is a growing interest in manipulating expression of such enzymes to better understand their biological roles. A new approach for determining their cellular activity is described, whereby LOOH reduction kinetics are tracked by high performance thin layer chromatography with peroxide-sensitive tetramethyl-p-phenylenediamine detection (HPTLC-TPD).

Role of mitochondrial cardiolipin peroxidation in apoptotic photokilling of 5-aminolevulinate-treated tumor cells.

In 5-aminolevulinic acid (ALA)-based photodynamic therapy (PDT), ALA taken up by tumor cells is metabolized to protoporphyrin IX (PpIX), which sensitizes photodamage leading to apoptotic or necrotic cell death. Since lipophilic PpIX originates in mitochondria, we postulated that photoperoxidation of highly unsaturated cardiolipin (CL), which anchors cytochrome c (cyt c) to the inner membrane, is an early proapoptotic event. As initial evidence, PpIX-sensitized photooxidation of liposomal CL to hydroperoxide (CLOOH) species precluded cyt c binding, but this could be reinstated by GSH/selenoperoxidase (GPX4) treatment.

Separation and quantitation of peroxidized phospholipids using high-performance thin-layer chromatography with tetramethyl-p-phenylenediamine detection.

A simple method for the selective determination of phospholipid hydroperoxide (PLOOH) families in complex lipid populations has been developed. Referred to as HPTLC-TPD, the method is based on PLOOH separation by normal-phase high-performance thin-layer chromatography, followed by spray detection with N,N,N',N'-tetramethyl-p-phenylenediamine and densitometric scanning of the purple bands. Parental phospholipids and alcohol analogues are unreactive.

Role of lipid hydroperoxides in photo-oxidative stress signaling.

Photosensitized peroxidation of membrane lipids has been implicated in skin pathologies such as phototoxicity, premature aging, and carcinogenesis, and may play a role in the antitumor effects of photodynamic therapy. Lipid hydroperoxides (LOOHs) are prominent early products of photoperoxidation that typically arise via singlet oxygen ((1)O(2)) attack. Nascent LOOHs can have several possible fates, including (i) iron-catalyzed one-electron reduction to chain-initiating free radicals, which exacerbate peroxidative damage, (ii) selenoperoxidase-catalyzed two-electron reduction to relatively innocuous alcohols, and (iii) translocation to other membranes, where reactions noted in (i) or (ii) might take place.

Quantitative spin trapping and triplet quenching by radicals for in vivo studies. I. The chemical model.

In order to determine quantitatively the free radical content and its changes affected by additives using spin trapping under in vivo conditions, an approach is suggested carrying out experiments in a completely mixed open system (CMOS). Measurements have been carried out for a chemical oxidation process as a model system, and analysis of products and of the spin trap was extended by kinetic ESR spectrometry of the spin adducts. Since in a CMOS differential equations of accumulation of all species can be transformed into algebraic expressions using available rate constants for the formation of the spin adducts, corresponding concentrations of free radicals have been calculated.

Hyperresistance to photosensitized lipid peroxidation and apoptotic killing in 5-aminolevulinate-treated tumor cells overexpressing mitochondrial GPX4.

Antitumor photodynamic therapy (PDT) with administered 5-aminolevulinic acid (ALA) is based on metabolism of ALA to protoporphyrin IX (PpIX), which acts as a sensitizer of photo-oxidative damage leading to apoptotic or necrotic cell death. An initial goal of this study was to ascertain how the PpIX-sensitized death mechanism for a breast tumor line (COH-BR1 cells) might be influenced by the conditions of ALA exposure in vitro. Two different treatment protocols were developed for addressing this question: (i) continuous incubation with 1 mM ALA for 90 min; and, (ii) discontinuous incubation, i.

Effect of multivitamins in an effervescent preparation on the respiratory burst of peritoneal macrophages in mice.

The effect of regular intake of low doses of an effervescent multivitamin preparation on the free-radical-producing activity of murine peritoneal macrophages under conditions resembling a possible infection was studied in vitro. Initially, several groups of mice were fed a basal diet and given, for 2 weeks, water without or with supplementation of either alpha -tocopherol, ascorbic acid, riboflavin or a multivitamin preparation. The supplementation period was followed by a 2-week wash-out time interval during which control and multivitamin groups received deionized water.