Effect of replacing calcium salts of palm oil distillate with extruded linseeds on milk fatty acid composition in Jersey and Holstein cows

Clinical and biomedical studies have provided evidence for the critical role of n-3 fatty acids on the reduction of chronic disease risk in humans, including cardiovascular disease. In the current experiment, the potential to enhance milk n-3 content in two breeds with inherent genetic differences in mammary lipogenesis and de novo fatty acid synthesis was examined using extruded linseeds. Six lactating cows (three Holstein and three Jersey) were used in a two-treatment switchback design with 3 × 21-day experimental periods to evaluate the effect of iso-energetic replacement of calcium salts of palm oil distillate (CPO) in the diet (34 g/kg dry matter (DM)) with 100 g/kg DM extruded linseeds (LIN). For both breeds, replacing CPO with LIN had no effect (P > 0.05) on DM intake or milk yield, but reduced (P < 0.05) milk fat and protein yield (on average, from 760 to 706 and 573 to 552 g/day, respectively). Relative to CPO, the LIN treatment reduced (P < 0.01) total saturated fatty acid content and enhanced (P < 0.001) 18:3n-3 in milk, whereas breed by diet interactions were significant for milk fat 16:0, total trans fatty acid and conjugated linoleic acid concentrations. Increases in 18:3n-3 intake derived from LIN in the diet were transferred into milk with a mean marginal transfer efficiency of 1.8%. Proportionate changes in milk fatty acid composition were greater in the Jersey, highlighting the importance of diet–genotype interactions on mammary lipogenesis. More extensive studies are required to determine the role of genotype on milk fat composition responses to oilseeds in the diet.

Towards a population ecology of stressed environments: the effects of zinc on the springtail Folsomia candida

1. To understand population dynamics in stressed environments it is necessary to join together two classical lines of research. Population responses to environmental stress have been studied at low density in life table response experiments. These show how the population's growth rate (pgr) at low density varies in relation to levels of stress. Population responses to density, on the other hand, are based on examination of the relationship between pgr and population density. 2. The joint effects of stress and density on pgr can be pictured as a contour map in which pgr varies with stress and density in the same way that the height of land above sea level varies with latitude and longitude. Here a microcosm experiment is reported that compared the joint effects of zinc and population density on the pgr of the springtail Folsomia candida (Collembola). 3. Our experiments allowed the plotting of a complete map of the effects of density and a stressor on pgr. Particularly important was the position of the pgr= 0 contour, which suggested that carrying capacity varied little with zinc concentration until toxic levels were reached. 4. This prediction accords well with observations of population abundance in the field. The method also allowed us to demonstrate, simultaneously, hormesis, toxicity, an Allee effect and density dependence. 5. The mechanisms responsible for these phenomena are discussed. As zinc is an essential trace element the initial increase in pgr is probably a consequence of dietary zinc deficiency. The Allee effect may be attributed to productivity of the environment increasing with density at low density. Density dependence is a result of food limitation. 6. Synthesis and applications. We illustrate a novel solution based on mapping a population's growth rate in relation to stress and population density. Our method allows us to demonstrate, simultaneously, hormesis, toxicity, an Allee effect and density dependence in an important ecological indicator species. We hope that the approach followed here will prove to have general applicability enabling predictions of field abundance to be made from estimates of the joint effects of the stressors and density on population growth rate.

Aluminium, antiperspirants and breast cancer

Aluminium salts are used as the active antiperspirant agent in underarm cosmetics, but the effects of widespread, long term and increasing use remain unknown, especially in relation to the breast, which is a local area of application. Clinical studies showing a disproportionately high incidence of breast cancer in the upper outer quadrant of the breast together with reports of genomic instability in outer quadrants of the breast provide supporting evidence for a role for locally applied cosmetic chemicals in the development of breast cancer. Aluminium is known to have a genotoxic profile, capable of causing both DNA alterations and epigenetic effects, and this would be consistent with a potential role in breast cancer if such effects occurred in breast cells. Oestrogen is a well established influence in breast cancer and its action, dependent on intracellular receptors which function as ligand-activated zinc finger transcription factors, suggests one possible point of interference from aluminium. Results reported here demonstrate that aluminium in the form of aluminium chloride or aluminium chlorhydrate can interfere with the function of oestrogen receptors of MCF7 human breast cancer cells both in terms of ligand binding and in terms of oestrogen-regulated reporter gene expression. This adds aluminium to the increasing list of metals capable of interfering with oestrogen action and termed metal I oestrogens. Further studies are now needed to identify the molecular basis of this action, the longer term effects of aluminium exposure and whether aluminium can cause aberrations to other signalling pathways in breast cells. Given the wide exposure of the human population to antiperspirants, it will be important to establish dermal absorption in the local area of the breast and whether long term low level absorption could play a role in the increasing incidence of breast cancer. (c) 2005 Elsevier Inc. All rights reserved.

Solid-state interconversions of coordination networks and hydrogen-bonded salts

Thermal or chemical treatment of crystalline 4,4-bipyridinium salts of [MCl4]2- (M=Co, Zn, Fe, or Pt) leads to HCl loss and formation of coordination network solids [{MCl2(4,4-bipy)}n]. For M=Co, Zn, and Fe, these solids can also be prepared by mechanochemical means. Their exposure to HCl vapor or the mechanochemical reaction of metal dichlorides with [4,4-H2bipy]Cl2 gives [4,4-H2bipy]2+ salts of [CoCl4]2-, [ZnCl4]2-, and, for the first time, [FeCl4]2-.

Dinuclear copper and zinc complexes of a hexaazamacrocycle containing p-xylyl spacers and bridging anions: theoretical and spectroscopic studies

The hexaazamacrocycle 7,22-dimethyl-3,7,11,18,22,26-hexaazatricyclo[26.2.2.2(13,16)] tetratriaconta-1(30), 13,15,28,31,33- hexaene (Me-2[30] pbz(2)N(6)) was synthesized and characterised by single crystal X-ray diffraction. The macrocycle adopts a conformation with the two aromatic rings almost parallel at a distance of ca. 4.24 Angstrom, but displaced relative to each other by ca. 1.51 Angstrom. The protonation constants of this compound and the stability constants of its complexes with Cu2+ and Zn2+, were determined in water - methanol (9 : 1 v/v) at 25 degreesC with ionic strength 0.10 mol dm(-3) in KCl. The potentiometric and spectroscopic studies (NMR of zinc, cadmium and lead complexes, and EPR of the copper complexes) indicate the formation of only dinuclear complexes. The association constants of the dinuclear copper complex with anions ( thiocyanate, terephthalate and glyphosate) and neutral molecules (1,4-benzenedimethanol, p-xylylenediamine and terephthalic acid) were determined at 20 degreesC in methanol. The structural preferences of this ligand and of its dinuclear copper(II) complex with a variety of bridging ligands were evaluated theoretically by molecular mechanics calculations (MM) and molecular dynamics (MD) using quenching techniques.

A monoaqua zinc complex. Unique acid dissociation behaviour

Using the I : 2 condensate of benzil dihydrazone and 2-acetylpyridine as the ligand L, two complexes of zinc, [ZnL(CH3COO)]PF6 (1) and [ZnL(H2O)CIO4]CIO4 H2O (2), are synthesised from Zn(CH3COO)(2).2H(2)O and Zn(CIO4)(2).6H(2)O, respectively. From X-ray crystallography, both the complexes are found to be single helical with the metal in distorted octahedral N4O2 environment. In 1, the two oxygen atoms come from the bidentate acetate while 2 is a monoaqua complex with a perchlorate anion bound to the metal in monodentate fashion. The perchlorate in 2 is not at all weakly bound [Zn-O(perchlorate) 2.256(4) A]. Still in acetonitrile solution, the coordinated perchlorate ion dissociates upon deprotonation [reaction (i)].

Zinc(II) mediated synthesis of an N-substituted 2-(2-pyridyl)imidazole from a 1,2-diketone and 2-(aminomethyl)pyridine and its ligational behaviour

Reaction of anhydrous ZnCl2 with the 1:2 condensate (L) of benzil and 2-(aminomethyl)pyridine in methanol gives monomeric ZnL'Cl-2 (1) where L' is 2-[(4,5-diphenyl-2-pyridin-2-yl-1H-imidazol-1-yl)-methyl]pyridine. In the X-ray crystal structure, 1 is found to contain tetrahedral zinc with an N2Cl2 coordination sphere and the N-substituent methylpyridine fragment hanging as a free arm. A tentative mechanism is proposed for the zinc mediated conversion of L-->L'. Demetallation of 1 by the action of aqueous NaOH yields L' in the free state. When L' is reacted with Zn(ClO4)(2).6H(2)O in a 1:2 molar proportion, [Zn(L')(2)](n)(ClO4)(2n).(H2O)(n/2).(CH2Cl2)(n/2) (2) is obtained. The zinc atom in 2, as revealed by X-ray crystallography, has a trigonal bipyramidal N-5 coordination sphere. There are two independent ligands in the asymmetric unit of 2. One of them bonds only to one zinc atom in a bidentate mode with the N-substituent methylpyridine hanging free while the other ligand binds to two different zinc atoms in a tridentate fashion, employing the N-substituent methylpyridine nitrogen atom to form the polymeric one-dimensional chain cation.

Synthesis and crystal structure of a 3-D zinc phosphate, [C5N2H14][Zn-2(PO3(OH))(3)], containing (4.8) net sheets

A new 3-D zinc phosphate, [C5N2H14][Zn-2(PO3(OH))(3)], has been synthesised under solvothermal conditions in the presence of 1-methylpiperazine. The structure, determined by single-crystal X-ray diffraction at 293 K (RMM = 520.9, orthorhombic, space group P2(1)2(1)2(1); a = 10.0517(2) &ANGS;, b = 10.4293(2) &ANGS; and c = 14.9050(5) &ANGS;; V = 1562.52 &ANGS;(3); Z = 4; R(F) = 2.60%, wR(F) = 2.93%), consists of vertex linked ZnO4 and PO3(OH) tetrahedra assembled into (4.8) net sheets which in turn are linked through further PO3(OH) units to generate a 3-D framework. 1-Methylpiperazinium cations reside within the 3-D channel system, held in place by a strong network of hydrogen bonds. The (4.8) net sheets occur in a number of zeolite structures e.g. ABW and GIS and related zinc phosphate phases. © 2004 Academie des sciences. Published by Elsevier SAS. All rights reserved.

Ditopic redox-active polyferrocenyl zinc(II) dithiocarbamate macrocyclic receptors: synthesis, coordination and electrochemical recognition properties

The synthesis of a range of ditopic polyferrocenyl zinc(II) dithiocarbamate macrocyclic receptors containing ferrocene groups on the macrocycle's periphery and/or as part of the cyclic cavity is reported. The assemblies have been characterised by a range of spectroscopic techniques, electrochemical studies and in two cases by X-ray structure determination. The ability of these host systems to bind and sense electrochemically anionic guest species, isonicotinate and benzoate, and neutral 4-picoline guest was examined by H-1 NMR and cyclic voltammetric titration studies. The strongest association was found between the isonicotinate anion and a dinuclear zinc(II) receptor whose macrocyclic cavity is of complementary size to complex this bidentate guest species in a cooperative manner. Cyclic voltammetric studies demonstrated that all receptors can electrochemically sense the binding of isonicotinate and benzoate via significant cathodic perturbations of the respective ferrocene redox couple.

Synthesis and crystal structure of a 3-D zinc phosphate, [C5N2H14][Zn2(PO3(OH))3], containing (4.8) net sheets

A new 3-D zinc phosphate, [C5N2H14][Zn-2(PO3(OH))(3)], has been synthesised under solvothermal conditions in the presence of 1-methylpiperazine. The structure, determined by single-crystal X-ray diffraction at 293 K (RMM = 520.9, orthorhombic, space group P2(1)2(1)2(1); a = 10.0517(2) &ANGS;, b = 10.4293(2) &ANGS; and c = 14.9050(5) &ANGS;; V = 1562.52 &ANGS;(3); Z = 4; R(F) = 2.60%, wR(F) = 2.93%), consists of vertex linked ZnO4 and PO3(OH) tetrahedra assembled into (4.8) net sheets which in turn are linked through further PO3(OH) units to generate a 3-D framework. 1-Methylpiperazinium cations reside within the 3-D channel system, held in place by a strong network of hydrogen bonds. The (4.8) net sheets occur in a number of zeolite structures e.g. ABW and GIS and related zinc phosphate phases. © 2004 Academie des sciences. Published by Elsevier SAS. All rights reserved.

Molecular dynamics simulations of threadlike cetyltrimethylammonium chloride micelles: effects of sodium chloride and sodium salicylate salts

We use atomistic molecular dynamics simulations to probe the effects of added sodium chloride (NaCl) and sodium salicylate (NaSal) salts on the spherical-to-threadlike micelle shape transition in aqueous solutions of cetyltrimethylammonium chloride (CTAC) surfactants. Long threadlike micelles are found to be unstable and break into spherical micelles at low concentrations or NaCl, but remain stable for 20 ns above a threshold value of [NaCl] approximate to 3.0 M, which is about 2.5 times larger than the experimental salt concentration at which the transition between spherical and rodlike micelles occurs. The chloride counterions associate weakly oil the surface of the CTAC micelles with the degree of counterion dissociation decreasing slightly with increasing [NaCl] on spherical micelles, but dropping significantly on the threadlike micelles tit high [NaCl]. This effect indicates that the electrolyte ions drive the micellar shape transition by screening the electrostatic repulsions between the micellar headgroups, The aromatic salicylate counterions, on the other hand, penetrate inside the micelle with their hydrophilic groups staying in the surfactant headgroup region and the hydrophobic groups partially embedded into the hydrophobic core of the micelle. The strong association of the salicylate ions with the surfactant headgroups leads to dense packing of the surfactant molecules, which effectively reduces the surface area per surfactant, and increases intramicellar ordering of the surfactant headgroups, favoring the formation of long threadlike micelles. Simulation predictions of the geometric and electrostatic properties of the spherical and threadlike micelles are in good agreement with experiments.

Supramolecular assemblies of metal ions in complex bimetallic and trimetallic salts based on hexacyanoferrate(III) ion

Two complex heterometallic salts with formulae Tl-6[Fe(CN)(6)](1) (33)(NO3)(OH) (1) and [Co(bpy)(2)(CN)(2)](2){[Ag(CN)(2)](0) (5)[Fe(CN)(6)](0) (5)} 8H(2)O (2) have been synthesized and fully characterized Single crystal X-ray analyses reveal that compound 1 is comprised of discrete Tl+ cations and [Fe(CN)(6)](3-) anions together with OH- and NO3- anions Compound 2 contains [Co(bpy)(2)(CN)(2)](+) cations and {[Ag(CN)(2)][Fe(CN)(6)]}(-) anions together with eight molecules of water of crystallization Both structures form unprecedented three-dimensional supramolecular networks via non covalent interactions Another important observation is that the stereochemically active inert (lone) pair present on Tl+ plays little role in controlling the structure of 1 The water molecules in 2 play important roles in providing stability organizing a supramolecular network through hydrogen bonding In the syntheses of 1 and 2 Fe(II) is oxidized to Fe(III) and Co(II) to Co(III) respectively facilitating the formation of the salts that are obtained Both compounds exhibit photoluminescence emission in solution near the visible region.

Synthesis, X-ray crystal structures and properties of complex salts and sterically crowded heteroleptic complexes of group 10 metal ions with aromatic sulfonyl dithiocarbimates and triphenylphosphine ligand

Two new complex salts of the form (Bu4N)(2)[Ni(L)(2)] (1) and (Ph4P)(2)[Ni(L)(2)] (2) and four heteroleptic complexes cis-M(PPh3)(2)(L) [M = Ni(II) (3), Pd(II) (4), L = 4-CH3OC6H4SO2N=CS2] and cis-M(PPh3)(2)(L') [M = Pd(II) (5), Pt(II) (6), L' = C6H5SO2N=CS2] were prepared and characterized by elemental analyses, IR, H-1, C-13 and P-31 NMR and UV-Vis spectra, solution and solid phase conductivity measurements and X-ray crystallography. A minor product trans-Pd(PPh3)(2)(SH)(2), 4a was also obtained with the synthesis of 4. The NiS4 and MP2S2 core in the complex salts and heteroleptic complexes are in the distorted square-plane whereas in the trans complex, 4a the centrosymmetric PdS2P2 core is perforce square planar. X-ray crystallography revealed the proximity of the ortho phenyl proton of the PPh3 ligand to Pd(II) showing rare intramolecular C-H center dot center dot center dot Pd anagostic binding interactions in the palladium cis-5 and trans-4a complexes. The complex salts with sigma(rt) values similar to 10 (5) S cm (1) show semi-conductor behaviors. The palladium and platinum complexes show photoluminescence properties in solution at room temperature.

Coordination behavior of symmetrical hexadentate O2N2S2-donor Schiff bases toward zinc (II): synthesis, characterization, and crystal structure

Two series of zinc(II) complexes of two Schiff bases (H2L1 and H2L2) formulated as [Zn(HL1/HL2)]ClO4 (1a and 1b) and [Zn(L1/L2)] (2a and 2b), where H2L1 = 1,8-bis(salicylideneamino)-3,6-dithiaoctane and H2L2 = 1,9-bis(salicylideneamino)-3,7-dithianonane, have been prepared and isolated in pure form by changing the chemical environment. Elemental, spectral, and other physicochemical results characterize the complexes. A single crystal X-ray diffraction study confirms the structure of [Zn(HL1)]ClO4 (1a). In 1a, zinc(II) has a distorted octahedral environment with a ZnO2N2S2 chromophore.