Tissue Sites of Uptake ofC-Labeled C60

This paper describes thein vivobehavior and potential metabolism of C₆₀and a more water-soluble quaternary ammonium salt-derivatized C₆₀. In both cases, a¹⁴C-labeled fullerene core was utilized for the target molecules that were intravenously injected into female Sprague–Dawley rats. The¹⁴C-labeled C₆₀(*C₆₀) was rapidly (within 1 min) cleared from the circulation and the majority of the *C₆₀accumulated in the liver (90–95%). *C₆₀was not eliminated from the liver over the 120-h period of this study. Our results also suggest that C₆₀is not metabolized by the typical oxidative patterns characteristic of other polycyclic aromatics. Therefore, although not acutely toxic, use of C₆₀, or its derivatives that could be cleaved back to the parent C₆₀in vivo, would likely lead to long-term fullerene accumulation in the liver. The uptake of *C₆₀and¹⁴C-labeled ammonium salt-derivatized C₆₀(1)by human keratinocytesin vitroshowed that while both *C₆₀and1are readily taken up by cells,1accumulates more slowly. Additionally, while C₆₀, at rather high concentrations (2.0 μM) and over extended periods of time (8 days), is able to inhibit the growth of human keratinocytes by about 50%, this effect showed little, if any, photoinducability.     

Metabolism of tritiated C19 steroids by shionogi mouse mammary tumors

In the present report, the metabolism of dehydroepiandrosterone, 5-androstene-3β, 17β-diol and androstenedione has been studied in two different Shionogi tumors, one is androgendependent (“androgen sensitive”) and grows in intact male mice and the other is apparently androgen-independent (“androgen insensitive”) since the cells continue to grow in castrated antiandrogen (Flutamide) treated male animals. Our data clearly show that both the sensitive and insensitive tumors contain 3β-hydroxysteroid Δ⁵-Δ⁴ isomerase which causes the transformation of C₁₉ steroids into potent androgenic steroids. However, the androgen sensitive tumor is able to convert 5-androstene-3β, l7β-diol into 2-hydroxyestrogens while the rate of conversion is extremely low in the insensitive tumor. Most interestingly, the production of 5α-reduced steroids observed in both tissues was clearly higher in insensitive tumor homogenates.     

Manipulation by 25-azacycloartanol of the relative percentage of C10, C9 and C8 side-chain sterols in suspension cultures of bramble cells

The addition of 25-azacycloartanol to the medium of suspension cultures of bramble cells resulted, after 6 weeks of growth, in a large decrease in the percentage of C₁₀ side-chain sterols, sitosterol and isofucosterol (83 % of the total in the control, 9 % in the treated cells), and in a spectacular increase in the percentage of C₈ side-chain sterols, cycloartenol, desmosterol and cholesterol (less than 1 % in the control, 53 % in the treated cells). In addition the relative percentage of C₉ side-chain sterols, mainly 24-methylene cholesterol increased significantly (from 16 to 37 %). A secondary effect of 25-azacycloartanol consisted in an increase of the percentage of Δ²⁴ sterols and in a decrease of the percentage of sterols with a saturated side chain. These results are in agreement with an inhibition by 25-azacycloartanol of the C-24 and C-28 methyltransferases and of the Δ²⁴ reductase.     

Relationship between allocation of absorbed light energy in PSII and photosynthetic rates of C3 and C4 plants

Two C₃ dicotyledonous crops and five C₄ monocotyledons treated with three levels of nitrogen were used to evaluate quantitatively the relationship between the allocation of absorbed light energy in PSII and photosynthetic rates (P _N) in a warm condition (25–26°C) at four to five levels [200, 400, 800, 1,200 (both C₃ and C₄) and 2,000 (C₄ only) μmol m⁻² s⁻¹] of photosynthetic photon flux density (PPFD). For plants of the same type (C₃ or C₄), there was a linear positive correlation between the fraction of absorbed light energy that was utilized in PSII photochemistry (P) and P _N, regardless of the broad range of their photosynthetic rates due to species-specific effect and/or nitrogen application; meanwhile, the fraction of absorbed light energy that was dissipated through non-photochemical quenching (D) showed a negative linear regression with P _N for each level of PPFD. The intercept of regression lines between P and P _N of C₃ and C₄ plants decreased, and that between D and P _N increased with increasing PPFD. With P and D as the main components of energy dissipation and complementary to each other, the fraction of excess absorbed light energy (E) was unchanged by P _N under the same level of PPFD. At the same level of P _N, C₄ plants had lower P and higher D than C₃ plants, due to the fact that C₄ plants with little or no photorespiration is considered a limited energy sink for electrons. Nevertheless there was a significant negative linear correlation between D and P when data from both C₃ and C₄ plants at varied PPFD levels was merged. The slope of regression lines between P and D was 0.85, indicating that in plants of both types, most of the unnecessary absorbed energy (ca. 85%) could dissipate through non-photochemical quenching, when P was inhibited by low P _N due to species-specific effect and nitrogen limitation at all levels of illumination used in the experiment.     

Strategies for engineering C4 photosynthesis

C₃ photosynthesis is an inefficient process, because the enzyme that lies at the heart of the Benson–Calvin cycle, ribulose 1,5-bisphosphate carboxylase-oxygenase (Rubisco) is itself a very inefficient enzyme. The oxygenase activity of Rubisco is an unavoidable side reaction that is a consequence of its reaction mechanism. The product of oxygenation, glycollate 2-P, has to be retrieved by photorespiration, a process which results in the loss of a quarter of the carbon that was originally present in glycollate 2-P. Photorespiration therefore reduces carbon gain. Purely in terms of carbon economy, there is, therefore, a strong selection pressure on plants to reduce the rate of photorespiration so as to increase carbon gain, but it also improves water- and nitrogen-use efficiency. Possibilities for the manipulation of plants to decrease the amount of photorespiration include the introduction of improved Rubisco from other species, reconfiguring photorespiration, or introducing carbon-concentrating mechanisms, such as inorganic carbon transporters, carboxysomes or pyrenoids, or engineering a full C₄ Kranz pathway using the existing evolutionary progression in C₃–C₄ intermediates as a blueprint. Possible routes and progress to suppressing photorespiration by introducing C₄ photosynthesis in C₃ crop plants will be discussed, including whether single cell C₄ photosynthesis is feasible, how the evolution of C₃–C₄ intermediates can be used as a blueprint for engineering C₄ photosynthesis, which pathway for the C₄ cycle might be introduced and the extent to which processes and structures in C₃ plant might require optimisation.     

Synthesis, crystal structure and vibrational spectroscopy of a novel mixed ligands Ni(II) pentaborate: [Ni(C4H10N2)(C2H8N2)2][B5O6(OH)4]2

A novel organic-inorganic hybrid pentaborate [Ni(C₄H₁₀N₂)(C₂H₈N₂)₂][B₅O₆(OH)₄]₂ has been synthesized by hydrothermal reaction and characterized by FT-IR, Raman spectroscopy, elemental analyses and DTA-TGA. Its crystal structure was determined from single crystal X-ray diffraction. The structure consists of isolated polyborate anion [B₅O₆(OH)₄]⁻ and nickel complex cation of [Ni(C₄H₁₀N₂)(C₂H₈N₂)₂]²⁺, in which the two kinds of ligands come from the decomposition of triethylenetriamine material. The [B₅O₆(OH)₄]⁻ units are connected to one another through hydrogen bonds, forming a three-dimensional framework with large channel along the a and c axes, in which the templating [Ni(C₄H₁₀N₂)(C₂H₈N₂)₂]²⁺ cations are located. The assignments of the record FT-IR absorption frequencies and Raman shifts were given.     

铕标记抗癌胚抗原单克隆抗体C17的研究和应用

用合成的N′-(对-异硫氰基苄基)-二乙三胺-N¹,N²,N³,N³-四乙酸铕钠为螫合剂.用Sephadex G-50凝胶柱层析分离标记C₁₇和过量试剂.分部收集的层析物的光密度图和荧光强度图完全一致.蛋白峰处两管标记C₁₇的比活性分别为5.2和8.9Eu³⁺离子每C₁₇分子,而且C₁₇的标记回收率为64%.标记C₁₇至少在6个月内是稳定的.用铕标记物得到的时间分辨免疫荧光分析的标准曲线具有良好线性和斜率,表明标记物免疫活性良好,而且已用于血清CEA分析.     

Host-guest properties of the trinuclear arene-ruthenium cluster cation [H3Ru3(C6H6)(C6Me6)2(O)]

The trinuclear arene-ruthenium cluster cation [H₃Ru₃(C₆H₆)(C₆Me₆)₂(O)]⁺, containing a μ₃-oxo cap and three arene ligands that span a hydrophobic pocket above the metal skeleton, has been crystallised as tetrafluoroborate salt in the presence of various guest molecules. The host-guest complexes have been characterised by single-crystal X-ray structure analysis. With chloroform as the guest molecule, a CHCl₃ molecule sits perfectly in the hydrophobic pocket, the hydrogen atom being encapsulated inside the cavity. When dioxane is added during the crystallisation process, the cluster forms infinite chains which are connected by a complex network of hydrogen bonds involving the μ₃-oxo ligand, water and dioxane molecules. Interestingly, in the presence of phenol, a water molecule is hydrogen-bonded between the μ₃-oxo ligand and the phenol molecule, forming a one-dimensional μ₃-O ? H₂O ? HO hydrogen-bonded chain. Finally, with benzoic acid, a head-to-tail host-guest chain is obtained, the phenyl ring being incorporated in the hydrophobic pocket, while the acid group is hydrogen-bonded to the μ₃-oxo ligand.     

Pyridine and phosphine reactions with [CPh3][B(C6F5)4]

Trityl borate salts [4-RPyCPh₃][B(C₆F₅)₄] (R = H 1, ^tBu 2, Et 3, NMe₂4) and [R₃PCPh₃][B(C₆F₅)₄] (R = Me 5, ⁿBu 6, Ph[1] 7, p-MeC₆H₄8) are readily prepared via equimolar reaction of the appropriate pyridine or phosphine and trityl borate [CPh₃][B(C₆F₅)₄]. The analogous reactions of PⁱPr₃ affords the product [(p-ⁱPr₃P-C₆H₄)Ph₂CH][B(C₆F₅)₄] (9) while the corresponding reactions of Cy₃P and ^tBu₃P gave the cyclohexadienyl derivatives [(p-R₃PC₆H₅)CPh₂][B(C₆F₅)₄] (R = Cy 10, ^tBu 11). X-ray structures of 5 and 9 are reported.     

Synthesis and characterization of some oxovanadium(V) complexes with internally functionalized oximes: Crystal and molecular structures of heptacoordinated [VO{ONC(CH3)(C4H3O-2)}3] and [VO{ONC(CH3)(C4H3S-2)}3] · 0.5C6H6

New oxovanadium(V) complexes with internally functionalized oximes of the type VO{OPrⁱ}_3−n{ONC(CH₃)(Ar)}_n] (where Ar = C₄H₃O-2, C₄H₃S-2 and C₅H₄N-2 and n = 1-3) have been prepared in quantitative yields by the reaction of VO(OPrⁱ)₃ with the corresponding oximes in various stoichiometric ratios in refluxing anhydrous benzene. The products have been characterized by elemental analyses and spectroscopic (FT IR, ¹H, ¹³C{¹H} and ⁵¹V NMR) studies. FAB mass spectral analysis of [VO{OPrⁱ}{ONC(CH₃)C₄H₃S}₂] indicates the monomeric nature of the complex. ⁵¹V NMR values for these complexes suggest the formation of tetra-coordinate species in solution. However, the single crystal X-ray diffraction studies of [VO{ONC(CH₃)(C₄H₃O-2)}₃] and [VO{ONC(CH₃)(C₄H₃S-2)}₃] · 0.5C₆H₆ exhibit the presence of vanadium(V) atoms in a unique hepta-coordination state with distorted pentagonal bipyramidal geometry in the solid state. The oxo- atom occupies the axial position while the oximato ligands are bonded in a dihapto (η²-N,O) manner with the formation of three membered rings.     

An aluminoborate cluster [AlB12O14(OH)12]: Synthesis and structure of [C5H6N][AlB12O14(OH)12]

A new aluminoborate, [C₅H₆N][AlB₁₂O₁₄(OH)₁₂], has been hydrothermally synthesized at 200 °C. The single-crystal diffraction study reveals that it crystallizes in space group C2/c. It consists of aluminoborate clusters [AlB₁₂O₁₄(OH)₁₂]⁻ and counterions [C₅H₆N]⁺. The aluminoborate cluster contains an Al(OH)₆ octahedron as a core that is capped by two raft-like polyborate units [B₆O₇(OH)₆]. These clusters are further interlinked by extensive hydrogen bonding to form a three-dimensional (3D) network, containing large channels along the b-axis, in which the [C₅H₆N]⁺ cations are located.     

Stereochemistry of the reaction products of the oxidative addition reaction of methyl iodide to [Rh((C4H3S)COCHCOR)(CO)(PPh3)]: A NMR and computational study. R = CF3, C6H5, C4H3S

A NMR study of the reaction mixture of the square planar [Rh((C₄H₃S)COCHCOR)(CO)(PPh₃)] complex and CH₃I, where R = CF₃, C₆H₅ or C₄H₃S, revealed that two types of alkyl and one (R = CF₃) or two (R = C₆H₅ or C₄H₃S) types of acyl species exist in the system. Two isomers of each species with an unsymmetrical β-diketonato ligand were observed. ¹H-¹H NOESY NMR unambiguously showed that the PPh₃ group is in the apical position in the more stable Rh^III-alkyl product. Theoretical computations of the equilibrium geometry of the possible reaction products, consistent with experimental observations, revealed that the first alkyl product results from trans addition to Rh^I and that the second thermodynamic alkyl product adopts an octahedral geometry with the PPh₃ group and the iodide above and below the square planar plane. Theoretical computations also revealed that the thermodynamic acyl product adopts a square-pyramidal geometry with the COCH₃ group in the apical position.     

Supramolecular salts containing the anionic [Ge(C2O4)3] complex and heteroaromatic amines

The crystalline compounds (Hbipy)₂[Ge(C₂O₄)₃] (1) and (Hphen)₂[Ge(C₂O₄)₃] · 2(H₂O) (2) [Hbipy⁺ is the 2,2′-bipyridinium cation (C₁₀H₉N₂), and Hphen⁺ is the 1,10′-phenathrolinium cation (C₁₂H₉N₂)] were isolated from mild hydrothermal syntheses and their structures were elucidated from single-crystal X-ray diffraction. The two compounds were further characterised by vibrational spectroscopy (FT-IR and FT-Raman), thermogravimetric analysis (TGA) and CHN elemental composition. Compounds 1 and 2 comprise the tris(oxalato-O,O′)germanate dianion complex, [Ge(C₂O₄)₃]²⁻, which co-crystallises with Hbipy⁺ (in 1), or Hphen⁺ and water molecules (in 2). In 1, the germanium oxalate anionic complex, [Ge(C₂O₄)₃]²⁻, and the Hbipy⁺ organic residues interact mutually via N-H?O hydrogen bonding interactions, leading to supramolecular discrete hydrogen-bonded units which are further interconnected via π-π stacking. Compound 2, on the other hand, exhibits a more complex hydrogen bonding network due to the presence of the water molecules of crystallisation which, along with π-π stacking between neighbouring Hphen⁺ residues, mediate the crystal packing.     

Molecular weights of glycollate oxidase from C3 and C4 plants determined during early stages of purification

The M_rs of glycollate oxidase (EC 1.1.3.1) (GAO) determined soon after extraction from the leaves of several C₃ and C₄ plants are reported. The enzyme isolated from the C₃ plants wheat, barley, spinach, pea and tobacco has M_r in the range 160–180 000 and is probably a homotetramer. GAO purified from pea was previously reported as a dimer and as an octamer from spinach leaves. Therefore the quaternary structure of these GAOs soon after extraction differs from that of the purified proteins. The enzymes from the C₄ plants maize and sugar cane have M_rs ca twice this value in the range 290–310 000, whilst that of the C₄ grass Panicum maximum has an M_r of 162 000. An improved spectrophotometric assay for GAO, using a non-carcinogenic dye, is described.     

Functional properties of diapophytoene and related desaturases of C30 and C40 carotenoid biosynthetic pathways

The desaturation reactions of C₃₀ carotenoids from diapophytoene to diaponeurosporene was investigated in vitro and by complementation in Escherichia coli. The expressed diapophytoene desaturase from Staphylococcus aureus inserts three double bonds in an FAD-dependent reaction. The enzyme is inhibited by diphenylamine. In the complementation experiment diapophytoene desaturase was able to convert C₄₀ phytoene to some extend but exhibited a high affinity to ζ-carotene. Comparison to the reaction of a phytoene desaturase from Rhodobacter capsulatus catalyzing a parallel three-step desaturation sequence with the corresponding C₄₀ carotenes revealed that this desaturase can also convert C₃₀ diapophytoene. Other homologous bacterial C₄₀ carotene desaturases could also utilize C₃₀ substrates, including one type of ζ-carotene desaturase which converted diaponeurosporene to diapolycopene. Further complementation experiments including the diapophytoene synthase gene from S. aureus revealed that the C₃₀ carotenogenic pathway is determined by this initial enzyme which is highly homologous to C₄₀ phytoene synthases.     

Synthesis and structure of a lead(II)-citrate: {Na(H2O)3}[Pb5(C6H5O7)3(C6H6O7)(H2O)3]·9.5H2O

The reaction of lead(II) nitrate with trisodium citrate Na₃(C₆H₅O₇) in a 1:22.5 ratio at pH 4.8 provides crystals of {Na(H₂O)₃}[Pb₅(H₂O)₃(C₆H₅O₇)₃(C₆H₆O₇)]·9.5H₂O (1). The structure of 1 is two-dimensional and exhibits five distinct Pb(II) sites and four different modes of citrate bonding. The five lead sites all display hemidirected coordination geometries, that is, irregular distribution of neighboring oxygen atoms resulting in obvious gaps in the coordination spheres. Consequently, the lead coordination geometries exhibit proximal bonding to a number of oxygen donors, as well as distal interactions with nearest neighbors. The coordination numbers vary from 8 to 10, with ‘5+3’, ‘5+4’, ‘6+4’ and ‘7+3’ coordination modes where the first number refers to the proximal ligands and the second to the distal set. The four crystallographically distinct citrate groups include three with deprotonated carboxylate groups (C₆H₅O₇)³⁻ and one with a single protonated carboxyl group (C₆H₆O₇)². The citrate ligands bridge 3, 5, 7 and 7 lead sites. Three of the citrate groups exhibit tridentate chelation coordination to a lead site through two carboxylate oxygen donors and the hydroxyl groups. One citrate group projects an uncoordinated -OH group and a pendant protonated carboxyl group into the interlamellar domain. This latter carboxyl group coordinates to a sodium cation, which exhibits five coordinate geometry defined by three aqua ligands and the carbonyl oxygen of the -CO₂H groups in the basal plane and a citrate -OH donor in the apical position.     

Difference in the development of tolerance to morphine and d-ala2-methionine-enkephalin in C57 BL/6J and DBA/2J mice

The analgesic effect elicited by intracerebroventricular (icv) administration of either morphine or d-ala²-methionine-enkephalin (d-ala²-met-enk) was studied during the onset and offset of morphine tolerance in DBA/2_J (DBA) and C₅₇ BL/6_J (C₅₇) strains of mice. DBA mice become tolerant to the analgesic effect of morphine icv injected after receiving 8 subcutaneous (sc) injections (2 injections daily × 4 days) of the ED₅₀ of morphine for analgesia. In c₅₇ mice tolerance to morphine icv-administered is evident after only a single sc injection of morphine ED₅₀. On the contrary the development of cross-tolerance to the analgesic effect of d-ala²-met-enk is similar in both strains of mice. With respect to the offset period, the recovery of the analgesic effect of morphine and d-ala²-met-enk is slower in C₅₇ than in DBA mice; in C₅₇ mice tolerance to both morphine and d-ala²-met-enk is still present 10 days after morphine withdrawal. These results suggest the existence of a strain dependent rate in the onset of tolerance to the analgesic effect of morphine. C₅₇ mice represent an interesting tool to investigate tolerance to opiates and opioid peptides.     

ansa-Chromocenes: An alternative route to Me2Si(C5Me4)2Cr

The mechanism for the preparation of Me₂Si(C₅Me₄)₂Cr, 1, from CrCl₂(THF)_x and Me₂Si(C₅Me₄)₂Li₂ was investigated and - in contrast to earlier claims - no evidence was found for the participation of an auxiliary ligand. The formation and stability of 1 is attributed to the combination of correct reaction conditions and a highly substituted ligand framework. Reactions with other ligands under identical conditions did not lead to the formation of ansa-chromocenes. Reaction with H₄C₂Ind₂Li₂ afforded the η³-Ind bridged dimer {H₄C₂(η⁵-Ind)(μ-,η³-Ind)Cr}₂, 9. Complex 1 does not coordinate PPh₃ or carbenes, but from reaction with two equivalents of xylyl isocyanide the CH-activated complex Me₂Si(C₅Me₄)(η³-C₅Me₃(H)(CH₂)Cr(CNC₆MeH₃)₂, 7, was obtained. Complexes 7 and 9 were characterised by X-ray crystallography.     

A novel unexpected luminescent quarternary coordination polymer {Sm3(C8H4O4)4(C12N2H8)2(NO3)}n with three high asymmetrical central Sm fragments by hydrothermal assembly

A novel chain-like luminescent samarium coordination polymer {Sm₃(C₈H₄O₄)₄(C₁₂N₂H₈)₂(NO₃)}_n (C₈H₄O₄ = phthalate, C₁₂N₂H₈ = 1,10-phenanthroline) has been assembled by hydrothermal process. The title complex crystallizes in the monoclinic system, space group P2(1)/c, with lattice parameters a = 22.56(3) Å, b = 11.155(15) Å, c = 20.32(3) Å, β = 96.70(2)°, V = 5078(12) ų, F(000) = 2964, GOF = 0.857, R₁ = 0.0358, wR₂ = 0.0597, Z = 4. Samarium ions exhibit different coordination modes from each other and lead to the unexpected high asymmetrical structure. To our knowledge, it is the first example of lanthanide coordination polymers comprising the three asymmetrical central Sm³⁺ fragments. The photophysical properties have been studied with excitation and emission spectra.     

Differential sensitivity of C3 and C4 turfgrass species to increasing atmospheric vapor pressure deficit

Temperature and vapor pressure deficit (VPD) effects on turfgrass growth are almost always confounded in experiments because VPD commonly is substantially increased in elevated-temperature treatments. The objective of this study as to examine specifically the influence of VPD on transpiration response of four ‘warm-season’ (C₄) and four ‘cool-season’ (C₃) turfgrasses to increasing VPD at a stable temperature (29.3 ± 1.5 °C). Although transpiration rates were noticeably lower in C₄ grasses, transpiration rates increased linearly in response to increasing VPD across the range of 0.8–3.0 kPa. In contrast, transpiration rates of C₃ increased sharply with increasing VPD across the range of low VPDs, but became constrained at higher VPDs (>1.35 kPa). Restricted transpiration rate at elevated VPD was most evident in Agrostis palustris and Lolium perenne. Assuming restricted transpiration rates reflect a limitation on leaf CO₂ uptake, these results indicate that the commonly observed decline in growth of C₃ (and success of C₄) grasses at elevated temperature may include a sensitivity to elevated VPD.