Effects of fish oil supplementation on prostaglandins in normal and tumor colon tissue: modulation by the lipogenic phenotype of colon tumors.

Dietary fish oils have potential for prevention of colon cancer, and yet the mechanisms of action in normal and tumor colon tissues are not well defined. Here we evaluated the impact of the colonic fatty acid milieu on the formation of prostaglandins and other eicosanoids. Distal tumors in rats were chemically induced to model inflammatory colonic carcinogenesis. After 21 weeks of feeding with either a fish oil diet containing an eicosapentaenoic acid/ω-6 fatty acid ratio of 0.4 or a Western fat diet, the relationships between colon fatty acids and prostaglandin E2 (PGE2) concentrations were evaluated. PGE2 is a key proinflammatory mediator in the colon tightly linked with the initiation and progression of colon cancer. The fish oil vs. the Western fat diet resulted in reduced total fatty acid concentrations in serum but not in colon. In the colon, the effects of the fish oil on fatty acids differed in normal and tumor tissue. There were distinct lipodomic patterns consistent with a lipogenic phenotype in tumors. In tumor tissue, the eicosapentaenoic acid/arachidonic acid ratio, cyclooxygenase-2 expression and the mole percent of saturated fatty acids were significant predictors of inter-animal variability in colon PGE2 after accounting for diet. In normal tissues from either control rats or carcinogen-treated rats, only diet was a significant predictor of colon PGE2. These results show that the fatty acid milieu can modulate the efficacy of dietary fish oils for colon cancer prevention, and this could extend to other preventive agents that function by reducing inflammatory stress.

Isolation of the first ferromagnetically coupled Mn(III/IV) complex.

Binuclear manganese complexes Mn2(III/IV)(dtsalpn)2DCBI, 1, Mn2(III/III)(dtsalpn)2HDCBI, 2, containing the ligand dicarboxyimidazole (DCBI) have been prepared in order to address the issue of imidazole bridged and ferromagnetically coupled Mn sites in high oxidation states of the OEC in Photosystem II (PS II). Temperature dependent magnetic susceptibility studies of 1 indicates that the interaction between the two Mn(III)/Mn(IV) ions is ferromagnetic (J = +1.4 cm(-1)). Variable temperature EPR spectra of 1 shows that a g = 2 multiline is as an excited state signal corresponding to S = 1/2.

Single crystal EPR and optical studies of paramagnetic ions doped zinc potassium phosphate hexahydrate--part I: Cu(II)--a case of orthorhombic symmetry.

Single crystal electron paramagnetic resonance (EPR) studies on Cu(II) doped zinc potassium phosphate hexahydrate (ZPPH) were carried out at room temperature. The angular variation spectra in the three orthogonal planes indicate that the paramagnetic impurity has entered the lattice substitutionally in place of Zn(II) and the spin Hamiltonian parameters calculated from these spectra are g(xx) = 2.188, g(yy) = 2.032, g(zz) = 2.373, Axx = 50 G, Ayy = 65.0 G and Azz = 80 G. The g and A tensors were coincident and these values matched fairly well with the values obtained from powder spectrum. The bonding parameters have also been calculated.

Single crystal EPR and optical studies of paramagnetic ions doped zinc potassium phosphate hexahydrate--part II: VO(II)--a case of substitutional site.

Single crystal electron paramagnetic resonance (EPR) studies were carried at room temperature for VO(II) doped zinc potassium phosphate hexahydrate. The results indicate that the paramagnetic impurity has entered the lattice only substitutionally, as confirmed by the single crystal rotations. The spin Hamiltonian parameters calculated from the spectra are g parallel = 1.9356, g perpendicular = 1.9764, A parallel = 200.9 G and A perpendicular = 76.5 G. The optical absorption spectrum exhibits three bands (800, 670 and 340 nm) suggesting the C4v symmetry and the optical parameters evaluated are Dq = 1492, Ds = -3854 and Dt = 186 cm(-1).

Single crystal EPR study of VO(II)-doped magnesium.

Single crystal EPR studies of VO(II)-doped magnesium potassium Tutton's salt have been carried out at room temperature. The results indicate that the paramagnetic impurity has entered the lattice, both substitutionally and interstitially and the maximum hyperfine for the substitutional site along the a axis corresponds to the minimum hyperfine for interstitial site and vice versa. The spin Hamiltonian parameters obtained from single crystal data for these sites are: Site 1, gparallel = 1.954(1); gperpendicular = 1.998(1), Aparallel = 19.80(2) mT; Aperpendicular = 7.61(2) mT; Site 2, gparallel = 1.997(1); gperpendicular = 1.952(1), Aparallel = 7.66(2) mT; Aperpendicular = 19.85(2) mT. Superhyperfine from ligand protons have been observed at certain orientations for Site 2 impurity. Powder spectrum shows a set of eight parallel and perpendicular features indicating the presence of only one site and these values matched with Site 1 values. From these observations, it has been concluded that the two vanadyl impurities are approximately at right angles to each other. Cooling the sample to 77 K does not change the spectra appreciably. The admixture coefficients have been calculated from Site 1 data, which agree well with the reported values.

Ferromagnetic Interactions in the Mn(N(3))(4)[Ni(en)(2)(NO(2))](2) Trinuclear Compound. Crystal Structure and Physical Properties.

The goal of this work was to design a ferromagnetically coupled Mn(2+)Ni(2+) species. For this, we attempted to combine nitro-nitrito and end-on azido bridges which are both known to be ferromagnetic couplers. This has led us to the compound of formula Mn(N(3))(4)[Ni(en)(2)NO(2)](2) (en = ethylenediamine). The crystal structure has been solved at room temperature. The compound crystallizes in the monoclinic system, space group C2, with a = 12.631(14) Å, b = 15.636(2) Å, c = 13.43(2) Å, beta = 90.14(6) degrees, and Z = 4. The structure consists of two very similar but crystallographically independent neutral trinuclear units with a MnNi(2) isoceles triangular shape. The Mn and Ni atoms are doubly bridged by an end-on azido and a nitro-nitrito (with respect to Ni and Mn, respectively) group. Both the temperature dependence of the magnetic susceptibility and the field dependence of the magnetization at 2 K have been investigated and have revealed Mn(2+)-Ni(2+) ferromagnetic interactions, which give rise to an S = (9)/(2) ground state for the triad. The quantitative interpretation of these magnetic properties has given an interaction parameter J between Mn(2+) and Ni(2+) ions equal to 1.4(1) cm(-)(1) (H = -JS(Mn)().(S(Ni1)() + S(Ni2)()). The electronic absorption spectrum has been recorded at various temperatures down to 20 K and interpreted.