A novel series of complexones with bis- or biazole structure as mixed ligands of paramagnetic contrast agents for MRI

We describe the syntheses, physicochemical properties and biological evaluation of a novel series of complexones containing bis- or biazoles moieties and two iminodiacetic acid units as novel ligands for paramagnetic lanthanides. The complexones were prepared by reaction of the corresponding 1,1′-bishaloethylbi- or bispyrazoles with methyl iminodiacetate and subsequent NaOH hydrolysis. 1,1′-Bisbromoethyl precursors were obtained by direct alkylation with an excess of 1,2-dibromoethane, or by heating the corresponding alcohol in HCl. Sigmoidal binding isotherms and MO calculations supported as most stable structures in solution, those containing two Gd(III) atoms bound per molecule of complexone with half saturation values S_0.5 (M⁻¹, 22 °C, pH 7.2) in the range 6.5 10⁻⁶0.5<36.1 10⁻⁶. Relaxivity properties [r₁, r₂, s⁻¹ mM⁻¹ Gd(III)] determined at 1.5 Tesla gave values (12.0<r₁<17.7, 12.2<r₂<20), improving significantly the relaxivities of reference compounds such as Gd(III)EDTA (5.2, 5.6) or Gd(III)DTPA (4.30, 4.30). These improvements involve mainly increased hydration and slower rotational motions. In vitro toxicity experiments are reported.     

Sequestration of Vascular Endothelial Growth Factor (VEGF) Induces Late Restrictive Lung Disease

Rationale

Neonatal respiratory distress syndrome is a restrictive lung disease characterized by surfactant deficiency. Decreased vascular endothelial growth factor (VEGF), which demonstrates important roles in angiogenesis and vasculogenesis, has been implicated in the pathogenesis of restrictive lung diseases. Current animal models investigating VEGF in the etiology and outcomes of RDS require premature delivery, hypoxia, anatomically or temporally limited inhibition, or other supplemental interventions. Consequently, little is known about the isolated effects of chronic VEGF inhibition, started at birth, on subsequent developing lung structure and function.

Objectives

To determine whether inducible, mesenchyme-specific VEGF inhibition in the neonatal mouse lung results in long-term modulation of AECII and whole lung function.

Methods

Triple transgenic mice expressing the soluble VEGF receptor sFlt-1 specifically in the mesenchyme (Dermo-1/rtTA/sFlt-1) were generated and compared to littermate controls at 3 months to determine the impact of neonatal downregulation of mesenchymal VEGF expression on lung structure, cell composition and function. Reduced tissue VEGF bioavailability has previously been demonstrated with this model.

Measurements and Main Results

Triple transgenic mice demonstrated restrictive lung pathology. No differences in gross vascular development or protein levels of vascular endothelial markers was noted, but there was a significant decrease in perivascular smooth muscle and type I collagen. Mutants had decreased expression levels of surfactant protein C and hypoxia inducible factor 1-alpha without a difference in number of type II pneumocytes.

Conclusions

These data show that mesenchyme-specific inhibition of VEGF in neonatal mice results in late restrictive disease, making this transgenic mouse a novel model for future investigations on the consequences of neonatal RDS and potential interventions.     

Recovery and characterization of a Citrus clementina Hort. ex Tan. 'Clemenules' haploid plant selected to establish the reference whole Citrus genome sequence

Background  

In recent years, the development of structural genomics has generated a growing interest in obtaining haploid plants. The use of homozygous lines presents a significant advantage for the accomplishment of sequencing projects. Commercial citrus species are characterized by high heterozygosity, making it difficult to assemble large genome sequences. Thus, the International Citrus Genomic Consortium (ICGC) decided to establish a reference whole citrus genome sequence from a homozygous plant. Due to the existence of important molecular resources and previous success in obtaining haploid clementine plants, haploid clementine was selected as the target for the implementation of the reference whole genome citrus sequence.     

Synthesis and characterization of novel palladium(II) complexes of bis(thiosemicarbazone). Structure, cytotoxic activity and DNA binding of Pd(II)-benzyl bis(thiosemicarbazonate).

The preparation of palladium(II) complexes of 3,5-diacyl-1,2,4-triazole bis(thiosemicarbazone) (H2L2), 2,6-diacylpyridine bis(thiosemicarbazone) (H2L3) and benzyl bis(thiosemicarbazone) (H2L4) is described. The new complexes [PdCl2(H2L2)] (1), [PdCl2(H2L3)] (2) and [PdL4].DMF (3) have been characterized by elemental analyses and spectroscopic studies (IR, 1H NMR and UV-Vis). The crystal and molecular structure of PdL4.DMF (L = bideprotonated form of benzyl bis(thiosemicarbazone)) has been determined by single-crystal X-ray diffraction: green triclinic crystal, a = 10.258(5), b = 10.595(5), c = 11.189(5) A, alpha = 97.820(5), beta = 108.140(5), gamma = 105.283(5) degrees, space group P1, Z = 1. The palladium atom is tetracoordinated by four donor atoms (SNNS) from L4 to form a planar tricyclic ligating system. The testing of the cytotoxic activity of compound 3 against several human, monkey and murine cell lines sensitive (HeLa, Vero and Pam 212) and resistant to cis-DDP (Pam-ras) suggests that compound 3 might be endowed with important antitumor properties since it shows IC50 values in a microM range similar to those of cis-DDP [cis-diamminedichloroplatinum(II)]. Moreover, compound 3 displays notable cytotoxic activity in Pam-ras cells resistant to cis-DDP (IC50 values of 78 microM versus 156 microM, respectively). On the other hand, the analysis of the interaction of this novel Pd-thiosemicarbazone compound with DNA secondary structure by means of circular dichroism spectroscopy indicates that it induces on the double helix conformational changes different from those induced by cis-DDP.     

Isolation and characterization of microsatellite markers for <Emphasis Type="Italic">Cedrela odorata</Emphasis> L. (Meliaceae), a high value neotropical tree

We describe 9 primers for amplification of microsatellite loci for the Neotropical tree Cedrela odorata L. (Meliaceae). Loci were isolated from an enriched library derived from a single DNA sample from a tree in Costa Rica. Levels of polymorphism were determined using samples from a large progeny trial. Across loci, the number of alleles ranged from 14 to 30. Observed heterozygosity levels ranged from 0.61 to 0.88. No linkage disequilibria were detected although some departures from Hardy-Weinberg equilibrium (HWE) were found, probably due to a Wahlund effect.     

Quartz Knapping Strategies in the Howiesons Poort at Sibudu (KwaZulu-Natal,South Africa)

The variability associated with Sibudu''s Howiesons Poort Industry highlights the unpredictable trajectory of technology in the Middle Stone Age. We reach this conclusion through a study of the technology on quartz from one of the Howiesons Poort layers (Grey Sand) from Sibudu rock shelter. Quartz bifacial technology has previously been described at the site, but this new in-depth study of the quartz technology reveals other strategies. First is the recurring employment of bipolar knapping, formerly considered as a defining feature of the Later Stone Age. Secondly, we highlight a laminar technology with emphasis on small quartz bladelets. Bipolar cores are most common, followed by prismatic cores. The knapping strategies in Grey Sand seem to involve systematic recycling and the deliberate production of microliths.     

Expanding the MiniAp‐4 BBB‐shuttle family: Evaluation of proline cis‐trans ratio as tool to fine‐tune transport

Venoms have recently emerged as a promising field in drug discovery due to their good selectivity and affinity for a wide range of biological targets. Among their multiple potential applications, venoms are a rich source of blood‐brain barrier (BBB) peptide shuttles. We previously described a short nontoxic derivative of apamin, MiniAp‐4, which can transport a wide range of cargoes across the BBB. Here, we have studied the conformation of the proline residue of a range of MiniAp‐4 analogues by high‐field NMR techniques, with the aim to identify whether there is a direct relation between the cis/trans population and a range of features, such as the capacity to transport molecules across a human‐based cellular model and stability in various media. The most promising candidate showed improved transport properties for a relevant small fluorophore.     

Fatty Aldehydes in Cyanobacteria Are a Metabolically Flexible Precursor for a Diversity of Biofuel Products

We describe how pathway engineering can be used to convert a single intermediate derived from lipid biosynthesis, fatty aldehydes, into a variety of biofuel precursors including alkanes, free fatty acids and wax esters. In cyanobacteria, long-chain acyl-ACPs can be reduced to fatty aldehydes, and then decarbonylated to alkanes. We discovered a cyanobacteria class-3 aldehyde-dehydrogenase, AldE, that was necessary and sufficient to instead oxidize fatty aldehyde precursors into fatty acids. Overexpression of enzymes in this pathway resulted in production of 50 to 100 fold more fatty acids than alkanes, and the fatty acids were secreted from the cell. Co-expression of acyl-ACP reductase, an alcohol-dehydrogenase and a wax-ester-synthase resulted in a third fate for fatty aldehydes: conversion to wax esters, which accumulated as intracellular lipid bodies. Conversion of acyl-ACP to fatty acids using endogenous cyanobacterial enzymes may allow biofuel production without transgenesis.     

Xylitol production from xylose by two yeast strains: Sugar tolerance

The kinetics and enzymology ofd-xylose utilization are studied in micro-, semi-, and aerobic batch cultures during growth ofCandida guilliermondii andCandida parapsilosis in the presence of several initial xylose concentrations. The abilities of xylitol accumulation by these two yeast strains are high and similar, although observed under various growth conditions. WithCandida parapsilosis, optimal xylitol production yield (0.74 g/g) was obtained in microaerobiosis with 100 g/L of xylose, whereas optimal conditions to produce xylitol byCandida guilliermondii (0.69 g/g) arose from aerobiosis with 300 g/L of sugar. The different behavior of these yeasts is most probably explained by differences in the nature of the initial step of xylose metabolism: a NADPH-linked xylose reductase activity is measured with a weaker NADH-linked activity. These activities seem to be dependent on the degree of aerobiosis and on the initial xylose concentration and correlate with xylitol accumulation.