Synthesis,spectral and magnetical characterization of monomeric [Cu(2-NO2bz)2(3-pyme)2(H2O)2] and polymeric [Cu{3,5-(NO2)2bz}2(3-pyme)2]n

Two new complexes of composition [Cu(2-NO₂bz)₂(3-pyme)₂(H₂O)₂] (1) and/or [Cu{3,5-(NO₂)₂bz}₂(3-pyme)₂] (2) (3-pyme = 3-pyridylmethanol, ronicol or 3-pyridylcarbinol, 2-NO₂bz = 2-nitrobenzoate and 3,5-(NO₂)₂bz = 3,5-dinitrobenzoate) have been prepared and studied by elemental analysis, electronic, infrared and EPR spectroscopy, magnetic susceptibility measurements and the structure of both complexes has been solved. Complex (1) shows an unusual molecular type of structure consisting of the [Cu(2-NO₂bz)₂(3-pyme)₂(H₂O)₂] molecules held together by hydrogen bonds and van der Waals interactions. Complex (2) exhibits a polymeric chain-like structure [Cu{3,5-(NO₂)₂bz}₂(3-pyme)₂]_n with copper atoms doubly bridged by two 3-pyridylmethanol molecules and the polymeric molecules are held together by van der Waals interactions. Complex (1) exhibits a magnetic moment μ_eff = 1.84 B.M. at 300 K that remains nearly constant within the temperature region (5–300 K). Further cooling results in lowering the magnetic moment to μ_eff = 1.82 B.M. at 1.8 K. The magnetic susceptibility temperature dependence obeys Curie–Weiss law with Curie constant of 0.423 cm³ K mol⁻¹ and with Weiss constant of −0.06 K. The magnetic moment of (2) exhibits a small increase with a decrease in the temperature (μ_eff = 1.80 B.M. at 300 K and μ_eff = 1.85 B.M. at 1.8 K) with Curie constant of 0.409 cm³ K mol⁻¹ and with Weiss constant of +1.1 K, which can indicate a very weak ferromagnetic interaction between the copper atoms within the chain. Applying the molecular field model resulted in obtaining zJ′ values −0.08 cm⁻¹ for complex (1), and −0.07 cm⁻¹ for complex (2), respectively, that could characterize intermolecular and interchain interactions transmitted through π–π stacking.     

Structural changes that occur upon photolysis of the Fe(II)a3–CO complex in the cytochrome ba3-oxidase of Thermus thermophilus: A combined X-ray crystallographic and infrared spectral study demonstrates CO binding to CuB

The purpose of the work was to provide a crystallographic demonstration of the venerable idea that CO photolyzed from ferrous heme-a₃ moves to the nearby cuprous ion in the cytochrome c oxidases. Crystal structures of CO-bound cytochrome ba₃-oxidase from Thermus thermophilus, determined at ~ 2.8–3.2 Å resolution, reveal a Fe–C distance of ~ 2.0 Å, a Cu–O distance of 2.4 Å and a Fe–C–O angle of ~ 126°. Upon photodissociation at 100 K, X-ray structures indicate loss of Fe_a3–CO and appearance of Cu_B–CO having a Cu–C distance of ~ 1.9 Å and an O–Fe distance of ~ 2.3 Å. Absolute FTIR spectra recorded from single crystals of reduced ba₃–CO that had not been exposed to X-ray radiation, showed several peaks around 1975 cm^? 1; after photolysis at 100 K, the absolute FTIR spectra also showed a significant peak at 2050 cm^? 1. Analysis of the ‘light’ minus ‘dark’ difference spectra showed four very sharp CO stretching bands at 1970 cm^? 1, 1977 cm^? 1, 1981 cm^? 1, and 1985 cm^? 1, previously assigned to the Fe_a3–CO complex, and a significantly broader CO stretching band centered at ~ 2050 cm^? 1, previously assigned to the CO stretching frequency of Cu_B bound CO. As expected for light propagating along the tetragonal axis of the P4₃2₁2 space group, the single crystal spectra exhibit negligible dichroism. Absolute FTIR spectrometry of a CO-laden ba₃ crystal, exposed to an amount of X-ray radiation required to obtain structural data sets before FTIR characterization, showed a significant signal due to photogenerated CO₂ at 2337 cm^? 1 and one from traces of CO at 2133 cm^? 1; while bands associated with CO bound to either Fe_a3 or to Cu_B in “light” minus “dark” FTIR difference spectra shifted and broadened in response to X-ray exposure. In spite of considerable radiation damage to the crystals, both X-ray analysis at 2.8 and 3.2 Å and FTIR spectra support the long-held position that photolysis of Fe_a3–CO in cytochrome c oxidases leads to significant trapping of the CO on the Cu_B atom; Fe_a3 and Cu_B ligation, at the resolutions reported here, are otherwise unaltered. This article is part of a Special Issue entitled: Respiratory Oxidases.     

Glycopeptide dendrimer colchicine conjugates targeting cancer cells

Screening of a 65,536-member one-bead-one-compound (OBOC) combinatorial library of glycopeptide dendrimers of structure ((βGal)_n + 1X⁸X⁷X⁶X⁵)₂DapX⁴X³X²X¹(β-Gal)_m (βGal = β-galactosyl-thiopropionic acid, X^8–1 = variable amino acids, Dap = l-2,3-diaminopropionic acid, n, m = 0, or 1 if X⁸ = Lys resp. X¹ = Lys) for binding of Jurkat cells to the library beads in cell culture, resynthesis and testing lead to the identification of dendrimer J1 (βGal-Gly-Arg-His-Ala)₂Dap-Thr-Arg-His-Asp-CysNH₂ and related analogues as delivery vehicles. Cell targeting is evidenced by FACS with fluorescein conjugates such as J1F. The colchicine conjugate J1C is cytotoxic with LD₅₀ = 1.5 μM. The β-galactoside groups are necessary for activity, as evidenced by the absence of cell-binding and cytotoxicity in the non-galactosylated, acetylated analogue AcJ1F and AcJ1C, respectively. The pentagalactosylated dendrimer J4 βGal₄(Lys-Arg-His-Leu)₂Dap-Thr-Tyr-His-Lys(βGal)-Cys) selectively labels Jurkat cell as the fluorescein derivative J4F, but its colchicine conjugate J4C lacks cytotoxicity. Tubulin binding assays show that the colchicine dendrimer conjugates do not bind to tubulin, implying intracellular degradation of the dendrimers releasing the active drug.

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Two new pseudohalide-bridged Cu(II) complexes with a hydrazone ligand: Syntheses,crystal structures and magnetic studies

Two new pseudohalide-bridged copper(II) complexes [{Cu(PBH)(μ_1,1-CNO)}₂] (1) and {Cu(PBH)(μ_1,5-NCNCN)}_n (2) (where HPBH = 2-pyridinecarboxaldehyde benzoyl hydrazone) have been synthesised and characterised by elemental analysis, CV, IR and UV–Vis spectral studies. The tridentate hydrazone pro-ligand (HPBH) was obtained by the condensation of benzhydrazide and pyridine-2-carboxaldehyde. Structures of both complexes have been established by X-ray crystallography which shows that 1 is a μ_1,1-CNO^?-bridged dimer whereas 2 is a μ_1,5-dca-bridged (dca = dicyanamide) linear polynuclear structure. Variable temperature magnetic susceptibility studies indicate weak antiferromagnetic interactions with J values ?0.50 cm^?1 and ?0.10 cm^?1 for 1 and 2, respectively.     

Synthesis,structures and magnetic properties of pentanuclear and trinuclear heterometallic complexes with bended and linear cyano-bridges (tren = tris(2-aminoethyl)amine)

The reaction of [Cu(tren)(OH₂)](ClO₄)₂ with KCN gave a mononuclear complex [Cu(tren)(CN)](ClO₄) (1) (tren = tris(2-aminoethyl)amine). Using 1 as a building block, one pentanuclear compound, [{Cu(tren)(NC)}₄Ni](ClO₄)₆ (2) and two trinuclear complexes, [{Cu(tren)NC}₂Co(tren)](ClO₄)₅ · 2H₂O (3), [{Cu(tren)CN}₂NiL](ClO₄)₄ (4) (L = 3,10-bis(2-hydroxyethyl)-1,3,5,8,10,12-hexaazacyclotetradecane) were prepared and characterized by single crystal X-ray analysis. In 1, Cu(II) atom adopts a distorted trigonal bipyramidal (TBP) geometry. In 2, the Ni(II) atom occupies the center of the pentanuclear compound with a square-planar coordination geometry. In 3, the six-coordinated Co(III) atom presents a distorted octahedral geometry with four nitrogen atoms from tren and two carbon atoms of bridged cyano groups in cis-positions. In 4, the nickel atom is located in an inversion center and coordinated with two [(tren)CuCN]⁺ moieties through cyano-bridging ligands. Magnetic susceptibility measurements of 2–4 show that the magnetic interactions between the heterometallic ions are antiferromagnetical coupling through the cyano bridges with g = 2.25, J = −0.142 cm⁻¹ and J′ = −0.167 cm⁻¹ for 2, g = 2.06, J = −0.094 cm⁻¹ for 3, and g = 2.20, J = −33.133 cm⁻¹ for 4. The correlations between the structures and the J values are discussed.     

Optimization of intravascular shear stress assessment in vivo

The advent of microelectromechanical systems (MEMS) sensors has enabled real-time wall shear stress (WSS) measurements with high spatial and temporal resolution in a 3-D bifurcation model. To optimize intravascular shear stress assessment, we evaluated the feasibility of catheter/coaxial wire-based MEMS sensors in the abdominal aorta of the New Zealand white (NZW) rabbits. Theoretical and computational fluid dynamics (CFD) analyses were performed. Fluoroscope and angiogram provided the geometry of aorta, and the Doppler ultrasound system provided the pulsatile flow velocity for the boundary conditions. The physical parameters governing the shear stress assessment in NZW rabbits included (1) the position and distance from which the MEMS sensors were mounted to the terminal end of coaxial wire or the entrance length, (L_e), (2) diameter ratios of aorta to the coaxial wire (D_aorta /D_{coaxial wire}=1.5–9.5), and (3) the range of Reynolds numbers (116–1550). At an aortic diameter of 2.4 mm and a maximum Reynolds number of 212 (a mean Reynolds number of 64.2), the time-averaged shear stress (τ_ave) was computed to be 10.06 dyn cm^?2 with a systolic peak at 33.18 dyn cm^?2. In the presence of a coaxial wire (D_aorta /D_{coaxial wire}=6 and L_e=1.18 cm), the τ_ave value increased to 15.54 dyn cm^?2 with a systolic peak at 51.25 dyn cm^?2. Real-time intravascular shear stress assessment by the MEMS sensor revealed an τ_ave value of 11.92 dyn cm^?2 with a systolic peak at 47.04 dyn cm^?2. The difference between CFD and experimental τ_ave was 18.5%. These findings provided important insights into packaging the MEMS sensors to optimize in vivo shear stress assessment.     

Occurrence of molecular abnormalities of cell cycle in L132 cells after in vitro short-term exposure to air pollution PM2.5

To improve the knowledge of the underlying mechanisms implying in air pollution Particulate Matter (PM)-induced lung toxicity in humans, we were interested in the sequential occurrence of molecular abnormalities from TP53-RB gene signaling pathway activation in the L132 target human lung epithelial cell model. The most toxicologically relevant physical and chemical characteristics of air pollution PM_2.5 collected in Dunkerque, a French highly-industrialized sea-side city, were determined. L132 cells were exposed during 24, 48 and 72 h to Dunkerque City's PM_2.5 (i.e. Lethal Concentration (LC)₁₀ = 18.84 μg PM/mL or 5.02 μg PM/cm²; LC₅₀ = 75.36 μg PM/mL or 20.10 μg PM/cm²), TiO₂ and desorbed PM (i.e. dPM; EqLC₁₀ = 15.42 μg/mL or 4.11 μg PM/cm²; EqLC₅₀ = 61.71 μg/mL or 16.46 μg PM/cm²), benzene (7 μM) or Benzo[a]Pyrene (B[a]P; 1 μM). Dunkerque City's PM_2.5 altered the gene expression and/or the protein concentration of several key cell cycle controllers from TP53-RB gene signaling pathway (i.e. P53; BCL2; P21; cyclin D1, cyclin-dependent kinase 1; retinoblastoma protein) in L132 cells, thereby leading to the occurrence of cell proliferation and apoptosis together. The activation of the critical cell cycle controllers under study might be related to PM-induced oxidative stress, through the possible involvement of covalent metals in redox systems, the metabolic activation of organic chemicals by enzyme-catalyzed reactions, and phagocytosis. Taken together, these results might ask the critical question whether there is a balance or, in contrast, rather an imbalance between the cell proliferation and the apoptosis occurring in PM-exposed L132 cells, with possible consequences in term of PM-induced lung tumorgenesis.     

Structure and magnetic properties of a trinuclear nickel(II) complex with benzenetricarboxylate bridge

Novel trinuclear Ni(II) complex [Ni₃(pmdien)₃(btc)(H₂O)₃](ClO₄)₃ · 4H₂O, 1 where pmdien = N,N,N′,N′,N″-pentamethyldiethylenetriamine, H₃btc = 1,3,5-benzenetricarboxylic (trimesic) acid, has been prepared and structurally characterized. Three nickel atoms are bridged by btc trianion and their coordination sphere is completed by three N atoms of pmdien and O atom of the water molecule. The three nickel(II) magnetic centers are equivalent and their coordination spheres are completed to deformed octahedrons. Magnetic susceptibility was measured over the temperature range 1.8–300 K and zJ′ = ?0.19 cm^?1, D = 3.79 cm^?1, g = 2.18 parameters were calculated.     

Structures,magnetic properties,and XPS of cyanide-bridged NdIII/SmIII/GdIII–CrIII complexes

Synthesis, structural characterization, and spectroscopic and magnetic properties of three new cyano-bridged 3d–4f bimetallic complexes, Ln^III(DMF)₄(H₂O)₃Cr^III (CN)₆ · nH₂O (Ln = Nd, Sm, Gd), have been described. The Nd–Cr complex crystallizes in the monoclinic P2₁/n space group with the following unit cell parameters: a = 20.063(7) Å, b = 8.967(4) Å, c = 18.023(6) Å, b = 96.12(3)°, V = 3224(2) Å³, and Z = 4. The neodymium (III) ion, which adopts anti-prism eight-coordination environment, is linked to the [Cr^III(CN)₆]³⁻ moiety through a bridging cyanide ligand with Nd–N = 2.550(4) Å and Nd–N–C = 164.4(4)°. The variable-temperature (0.5 T at 2–300 K) and variable-field (0–5 T at 2 and 5 K) magnetic measurements reveal that the weak interaction of Gd–Cr complexes differs from that of Nd–Cr and Sm–Cr ones mainly because of the lack of orbital angular momentum. The XPS and diffuse reflectance electronic spectra were also measured to discuss charge transfer transitions concerning π-backdonation from the viewpoint of magneto-optical functions.     

Toxicity and repellency of origanum essential oil and its components against Tribolium castaneum (Coleoptera: Tenebrionidae) adults

The components of Origanum vulgare L. essential oil showing insecticidal activity and repellency against red flour beetle, Tribolium castaneum (Coleoptera: Tenebrionidae), adults were analysed by GC-MS. All constituents were identified, and the main components were carvacrol (67.2%), p-cymene (16.2%), γ-terpinene (5.5%), thymol (4.9%), and linalool (2.1%). In a vapor phase fumigant assay, the origanum oil was more effective in closed conditions (LD₅₀ = 0.055 mg/cm³) than in open conditions (LD₅₀ > 0.353 mg/cm³). This suggests that toxicity is exerted largely in the vapor phase. Based on 24-h LD₅₀ values, the toxicity of caryophyllene oxide (0.00018 mg/cm³) was comparable with that of dichlorvos (0.00007 mg/cm³). In addition, thymol, camphene, α-pinene, p-cymene, and γ-terpinene showed good insecticidal activity (LD₅₀ = 0.012–0.195 mg/cm³). In repellency tests using 9 constituents of origanum oil, caryophyllene oxide showed complete repellency at 0.03 mg/cm². Hydrogenated monoterpenoids, such as thymol, α-pinene, carvacrol, and myrcene, elicited strong repellency at 0.03 and 0.006 mg/cm². Repellency depended on both time and concentration. These results indicate that origanum oil and its components could be potential candidates as a fumigant and repellent for managing T. castaneum adults.     

Profiling oestrogens and testosterone in human urine by stable isotope dilution/benchtop gas chromatography–mass spectrometry

Oestrogens, such as oestrone (E₁), 17β-oestradiol (E₂), oestriol (E₃) and their biologically active metabolites 2-methoxyoestrone (2-MeOE₁), 2-hydroxyoestradiol (2-OHE₂) 16-ketooestradiol (16-OE₂), 16-epioestriol (16-epiE₃), as well as testosterone (T) play an important role in physiological and pathological developmental processes during human development. We therefore aimed at developing an isotope dilution/bench top gas chromatography–mass spectrometry (ID/GC–MS) method, based on benchtop GC–MS, for the simultaneous determination (‘profiling’) of the above analytes in children. The method consisted of equilibration of urine (5 ml) with a cocktail containing stable isotope-labelled analogues of the analytes as internal standards ([2,4-²H₂]E₁, [2,4,16,16-²H₄]E₂, [2,4,17-²H₃]E₃, [16,16,17-²H₃]T, [1,4,16,16-²H₄]2-MeOE₁, [1,4,16,16,17-²H₅]2-OHE₂, [2,4,15,15,17-²H₅]16-OE₂ and [2,4-²H₂]16-epiE₃). Then, solid-phase extraction (C₁₈ cartridges), enzymatic hydrolysis (sulphatase from Helix pomatia (type H-1)), re-extraction, purification by anion exchange chromatography and derivatisation to trimethylsilyl ethers followed. The samples were analysed by GC–MS (Agilent GC 6890N/5975MSD; fused silica capillary column 25 m × 0.2 mm i.d., film 0.10 μm). Calibration plots were linear and showed excellent reproducibility with coefficients of determination (r²) between 0.999 and 1.000. Intra- and inter-assay coefficients of variation (CV) were <2.21% for all quantified metabolites. Sensitivity was highest for 2-OHE₂ (0.25 pg per absolute injection: signal-to-noise ratio (S/N) = 3) and lowest for 16-epiE₃ (2 pg per absolute injection: S/N = 2.6), translating into corresponding urine sample analyte concentrations of 0.025 ng ml^?1 and 0.2 ng ml^?1, respectively. Accuracy – determined in a two-level spike experiment – showed relative errors ranging between 0.15% for 16-OE₂ and 11.63% for 2-OHE₂. Chromatography showed clear peak shapes for the components analysed. In summary, we describe a practical, sensitive and specific ID/GC–MS assay capable of profiling the above-mentioned steroids in human urine from childhood onwards.     

Binding of diarrheic shellfish poisoning toxins to okadaic acid binding proteins purified from the sponge Halichondria okadai

Okadaic acid (OA) and dinophysistoxin-1 (DTX1) cause diarrheic shellfish poisoning. This article examines the biochemical interactions of the two toxins with novel okadaic acid binding proteins (OABPs) 2.1 and 2.3, originally isolated from the marine sponge Halichondria okadai. First, recombinant OABPs 2.1 and 2.3 were expressed in Escherichia coli BL21 (DE3) cells. Binding assays using [24-³H]OA and the recombinant OABP 2.1 or 2.3 demonstrated the dissociation constant K_d of 1.30 ± 0.56 nM and 1.54 ± 0.35 nM, respectively. Binding of [24-³H]okadaic acid to recombinant OABP2.1 was almost equally replaced with OA and DTX1. OA-induced cytotoxicity in mouse leukemia P388 cells was inhibited in the presence of the recombinant OABPs 2.1 and 2.3 with an EC₅₀ of 92 ± 8.4 nM and 87 ± 13 nM, respectively. These results suggest that the blockage of OA-induced cytotoxicity by OABPs 2.1 and 2.3 may be involved in regulating symbiotic relationships present in the sponge H. okadai.     

Allelopathic interactions between the macroalga Hizikia fusiformis (Harvey) and the harmful blooms-forming dinoflagellate Karenia mikimotoi

The effects of algal blooms on seaweeds have been rarely studied, although harmful algal blooms (HABs) are now normally regarded as worldwide incidents. In the present study, the effects of dense Karenia mikimotoi cells on the growth and photosynthesis of Hizikia fusiformis, a common and commercially cultivated macroalga in coastal waters of the East China Sea (ECS), were studied to understand the possible consequences when the mariculture encountered a dense harmful algal bloom. Furthermore, the counteraction of the latter on the growth and photosynthetic activities of K. mikimotoi was determined to evaluate the contribution of H. fusiformis commercial cultivation to environmental improvements. The results showed that the chlorophyll a (Chl a) contents, maximal photochemical efficiency (F_v/F_m) and relative electron transfer rate (rETR) of gas vesicles (specialized leaves), adult and young receptacles of H. fusiformis were all significantly (P < 0.05) inhibited compared with the mono-cultured ones. When compared with mono-cultured H. fusiformis (without K. mikimotoi), the Chl a contents in gas vesicles, adult and young receptacles decreased by 20.6%, 17.6% and 33.2% within 2 weeks. Correspondingly, the F_v/F_m decreased by 7.9%, 37.4% and 43.7%; the apparent photosynthetic efficiency (α) decreased by 9.4%, 47.1% and 48.3%; and rETR decreased by 19.5%, 52.6% and 68.2%, respectively. The Chl a concentration of the mono-cultured K. mikimotoi (without H. fusiformis) increased to 2247.97 μg l⁻¹ from 958.11 μg l⁻¹ within 14 d. Those of the co-cultivated ones (with H. fusiformis), however, increased to 1591.31 μg l⁻¹ on the 8th day and then decreased rapidly to 254.99 (±37.73) μg l⁻¹ after the next 6 days. Furthermore, compared with the mono-cultured K. mikimotoi cells, the F_v/F_m, α and rETR_max of co-cultivated ones decreased by 9.4%, 36.3% and 30.6%, respectively. The results indicated that the mature sporophytes of H. fusiformis were resistant to dense K. mikimotoi blooms and this resistance was organ-dependent as: gas vesicle > adult receptacles > young receptacles. On the other hand, commercial mariculture of H. fusiformis demonstrated the potential of preventing the occurrence of algal blooms.     

Metal cations modulate the bacteriochlorophyll–protein interaction in the light-harvesting 1 core complex from Thermochromatium tepidum

The light-harvesting 1 reaction center (LH1-RC) complex from Thermochromatium (Tch.) tepidum exhibits unusual Q_y absorption by LH1 bacteriochlorophyll-a (BChl-a) molecules at 915 nm, and the transition energy is finely modulated by the binding of metal cations to the LH1 polypeptides. Here, we demonstrate the metal-dependent interactions between BChl-a and the polypeptides within the intact LH1-RC complexes by near-infrared Raman spectroscopy. The wild-type LH1-RC (B915) exhibited Raman bands for the C3-acetyl and C13-keto CO stretching modes at 1637 and 1675 cm^? 1, respectively. The corresponding bands appeared at 1643 and 1673 cm^? 1 when Ca^2 + was biosynthetically replaced with Sr^2 + (B888) or at 1647 and 1669 cm^? 1 in the mesophilic counterpart, Allochromatium vinosum. These results indicate the significant difference in the BChl–polypeptide interactions between B915 and B888 and between B915 and the mesophilic counterpart. The removal of the original metal cations from B915 and B888 resulted in marked band shifts of the C3-acetyl/C13-carbonyl νCO modes to ~ 1645/~ 1670 cm^? 1, supporting a model in which the metal cations are involved in the fine-tuning of the hydrogen bonding between the BChl-a and LH1-polypeptides. Interestingly, the interaction modes were almost identical between the Ca^2 +-depleted B915 and Sr^2 +-depleted B888 and between B915 and Ca^2 +-substituted B888, despite the significant differences in their LH1 Q_y peak positions and the denaturing temperatures, as revealed by differential scanning calorimetry. These results suggest that not only the BChl–polypeptide interactions but some structural origin may be involved in the unusual Q_y red-shift and the enhanced thermal stability of the LH1-RC complexes from Tch. tepidum.     

The binding of okadaic acid analogs to recombinant OABP2.1 originally isolated from the marine sponge Halichondria okadai

The binding between [24-³H]okadaic acid (OA) and a recombinant OA binding protein OABP2.1 was examined using various OA analog, including methyl okadaate, norokadanone, 7-deoxy OA, and 14,15-dihydro OA, 7-O-palmitoyl DTX1, to investigate the structure activity relationship. Among them, 7-O-palmitoyl DTX1, which is one of the diarrhetic shellfish poisoning (DSP) toxins identified in shellfish, displayed an IC₅₀ for [24-³H]OA binding at 51 ± 6.3 nM (Mean ± SD). In addition, a synthetic compound, N-pyrenylmethyl okadamide, exhibited its IC₅₀ at 10 ± 2.9 nM (Mean ± SD). These results suggested that the recombinant OABP2.1 and the N-pyrenylmethyl okadamide might be core substances in a novel assay for the DSP toxins.     

Syntheses,structures, and magnetic properties of heterobimetallic complexes based on tetracyanometallic building blocks

Two tetracyanometalate building blocks, [Fe(5,5′-dmbipy)(CN)₄]^? (2) and [Fe(4,4′-dmbipy)(CN)₄]^? (3) (5,5′-dmbipy = 5,5′-dimethyl-2,2′-bipyridine; 4,4′-dmbipy = 4,4′-dimethyl-2,2′-bipyridine), and two cyano-bridged heterobimetallic complexes, [Cu₂(bpca)₂(H₂O)₂Fe₂(5,5′-dmbipy)₂(CN)₈] · 2[Cu(bpca)Fe(5,5′-dmbipy)(CN)₄] · 4H₂O (4) and [Cu(bpca)Fe(4,4′-dmbipy)(CN)₄]_n (5) (bpca = bis(2-pyridylcarbonyl)amidate), have been synthesized and structurally characterized. Complex 4 contains two dinuclear and one tetranuclear heterobimetallic clusters in an asymmetric unit whereas the structure of complex 5 features a one-dimensional heterobimetallic zigzag chain. The Cu(II) ion is penta-coordinated in the form of a distorted square-based pyramid. Magnetic studies show ferromagnetic coupling between Cu(II) and Fe(III) ions with g = 2.28, J₁ = 2.64 cm^?1, J₂ = 5.40 cm^?1 and TIP = ?2.36 × 10^?3 for complex 4, and g = 2.17, J = 4.82 cm^?1 and zJ′ = 0.029 cm^?1 for complex 5.     

Ferromagnetic exchange coupling in the linear,chloride-bridged cluster (cyclam)CoII[(μ-Cl)UIV(Me2Pz)4]2

The trinuclear cluster (cyclam)Co[(μ-Cl)U(Me₂Pz)₄]₂ (cyclam = 1,4,8,11-tetraazacyclotetradecane, Me₂Pz^? = 3,5-dimethylpyrazolate) is synthesized through cleavage of the homoleptic dimer [U(Me₂Pz)₄]₂ by (cyclam)CoCl₂. A single crystal X-ray diffraction analysis reveals a linear chloride-bridged structure analogous to that previously reported for (cyclam)M[(μ-Cl)U(Me₂Pz)₄]₂ (M = Ni, Cu, Zn). The magnetic exchange coupling of the CoU₂ cluster was probed by analyzing the temperature dependence of its magnetic susceptibility. Comparison of χ_MT versus T between the CoU₂ species and the diamagnetic ZnU₂ cluster demonstrates the presence of ferromagnetic coupling between the Co^II and U^IV centers. We present methods for estimating upper and lower bounds for the exchange interaction energy in such systems and find that for CoU₂, the exchange constant, J, lies in the range 15–48 cm^?1. Application of these methods to the previously reported NiU₂ cluster suggests somewhat weaker ferromagnetic exchange, with J lying in the range 2.8–19 cm^?1. AC magnetic susceptibility experiments were not indicative of single-molecule magnet behavior for the CoU₂ cluster, although qualitative interpretation of the low-temperature magnetization data suggests the presence of significant zero-field splitting in the ground state.     

Two new N-heterocyclic carbene silver(I) complexes with the π–π stacking interactions

The precursors bis[N-(alkyl)benzimidazoliumylmethyl]durene halide (1a: alkyl = C₂H₅, halide = Br^?; 1b: alkyl = n-C₄H₉, halide = Cl^?; durene = 1,2,4,5-tetramethylbenzene) and their two new NHC silver(I) complexes [Durene(CH₂BimyEtAgBr)₂] (2a) and [Durene(CH₂BimyⁿBuAgCl)₂] (2b) (Bimy = benzimidazol-2-ylidene) have been prepared and characterized. In the crystal structures of 2a and 2b the aromatic π–π stacking interactions are observed.     

Effects of short- and long-term changes in spatial density on the social behavior of captive chimpanzees (Pan troglodytes)

The constraints of captivity may often require non-human primates to experience restrictions in space for both long- and short-term periods of time. The tension-reduction model predicts that great apes should increase affiliative behaviors and decrease aggressive behaviors as a coping strategy. The conflict avoidance model, however, predicts that great apes should decrease all social interactions (affiliative and aggressive) as a coping strategy. The purpose of this study was to test the conflict-avoidance and tension-reduction models by examining the effects of both short-term (1–2 days) and long-term (6 months) changes in spatial density on social behavior in 23 adult captive chimpanzees (6 males, 17 females) housed at the Primate Foundation of Arizona. Affiliative (i.e., social groom, social play) and agonistic (i.e., charging display, attack) were assessed using scan-sampling techniques while subjects were rotated from high-density to low-density conditions for varying lengths of time. Results of short-term increases in spatial density (crowding) supported the conflict-avoidance strategy for females, through reduced levels of aggressive (F_1,16 = 17.11, p = 0.001) and affiliative (F_1,16 = 21.13, p < 0.001) behaviors. Males, however, supported the tension-reduction model during short-term high-density by decreasing aggression (F_1,5 = 10.53, p = 0.02) while increasing affiliation (F_1,5 = 9.10, p = 0.03). Females partially supported the tension-reduction model during long-term high-density by increasing affiliative behaviors (F_1,16 = 14.19, p = 0.002) compared to short-term high-density levels, while rates of aggression remained low. Finally, males supported the tension-reduction by reducing aggression (F_1,5 = 7.668, p = 0.04) and increasing affiliation (F_1,5 = 6.08, p = 0.05) during long-term high-density. Results confirm that chimpanzees use different strategies during short-term versus long-term increases in spatial density and that these strategies may be influenced by individual sex. However, sample sizes are small and additional research on male chimpanzees is needed.     

Structure and water permeability of fully hydrated diphytanoylPC

Diphytanoylphosphatidylcholine (DPhyPC) is a branched chain lipid often used for model membrane studies, including peptide/lipid interactions, ion channels and lipid rafts. This work reports results of volume measurements, water permeability measurements P_f, X-ray scattering from oriented samples, and X-ray and neutron scattering from unilamellar vesicles at T = 30 °C. We measured the volume/lipid V_L = 1426 ± 1 Å³. The area/lipid was found to be 80.5 ± 1.5 Å² when both X-ray and neutron data were combined with the SDP model analysis (Ku?erka, N., Nagle, J.F., Sachs, J.N., Feller, S.E., Pencer, J., Jackson, A., Katsaras, J., 2008. Lipid bilayer structure determined by the simultaneous analysis of neutron and X-ray scattering data. Biophys. J. 95, 2356–2367); this is substantially larger than the area of DOPC which has the largest area of the common linear chain lipids. P_f was measured to be (7.0 ± 1.0) × 10^?3 cm/s; this is considerably smaller than predicted by the recently proposed 3-slab model (Nagle, J.F., Mathai, J.C., Zeidel, M.L., Tristram-Nagle, S., 2008. Theory of passive permeability through lipid bilayers. J. Gen. Physiol. 131, 77–85). This disagreement can be understood if there is a diminished diffusion coefficient in the hydrocarbon core of DPhyPC and that is supported by previous molecular dynamics simulations (Shinoda, W., Mikami, M., Baba, T., Hato, M., 2004. Molecular dynamics study on the effects of chain branching on the physical properties of lipid bilayers. 2. Permeability. J. Phys. Chem. B 108, 9346–9356). While the DPhyPC head–head thickness (D_HH = 36.4 Å), and Hamaker parameter (H = 4.5 × 10^?21 J) were similar to the linear chain lipid DOPC, the bending modulus (K_C = 5.2 ± 0.5 × 10^?21 J) was 30% smaller. Our results suggest that, from the biophysical perspective, DPhyPC belongs to a different family of lipids than phosphatidylcholines that have linear chain hydrocarbon chains.