Benefit of heparin in peripheral venous and arterial catheters: systematic review and meta-analysis of randomised controlled trials

Objective: To evaluate the effect of heparin on duration of catheter patency and on prevention of complications associated with use of peripheral venous and arterial catheters.

Isolation of the Ornithine-δ-Aminotransferase cDNA and Effect of Salt Stress on Its Expression in Arabidopsis thaliana1

To evaluate the relative importance of ornithine (Orn) as a precursor in proline (Pro) synthesis, we isolated and sequenced a cDNA encoding the Orn-δ-aminotransferase (δ-OAT) from Arabidopsis thaliana. The deduced amino acid sequence showed high homology with bacterial, yeast, mammalian, and plant sequences, and the N-terminal residues exhibited several common features with a mitochondrial transit peptide. Our results show that under both salt stress and normal conditions, δ-OAT activity and mRNA in young plantlets are slightly higher than in older plants. This appears to be related to the necessity to dispose of an easy recycling product, glutamate. Analysis of the expression of the gene revealed a close association with salt stress and Pro production. In young plantlets, free Pro content, Δ1-pyrroline-5-carboxylate synthase mRNA, δ-OAT activity, and δ-OAT mRNA were all increased by salt-stress treatment. These results suggest that for A. thaliana, the Orn pathway, together with the glutamate pathway, plays an important role in Pro accumulation during osmotic stress. Conversely, in 4-week-old A. thaliana plants, although free Pro level also increased under salt-stress conditions, the δ-OAT activity appeared to be unchanged and δ-OAT mRNA was not detectable. Δ1-pyrroline-5-carboxylate synthase mRNA was still induced at a similar level. Therefore, for the adult plants the free Pro increase seemed to be due to the activity of the enzymes of the glutamate pathway.

Genetic and molecular analysis of the gypsy chromatin insulator of Drosophila.

Boundary or insulator elements set up independent territories of gene activity by establishing higher order domains of chromatin structure. The gypsy retrotransposon of Drosophila contains an insulator element that represses enhancer-promoter interactions and is responsible for the mutant phenotypes caused by insertion of this element. The gypsy insulator inhibits the interaction of promoter-distal enhancers with the transcription complex without affecting the functionality of promoter-proximal enhancers; in addition, these sequences can buffer a transgene from chromosomal position effects. Two proteins have been identified that bind gypsy insulator sequences and are responsible for their effects on transcription. The suppressor of Hairy-wing [su(Hw)] protein affects enhancer function both upstream and downstream of its binding site by causing a silencing effect similar to that of heterochromatin. The modifier of mdg4 [mod(mdg4)] protein interacts with su(Hw) to transform this bi-directional repression into the polar effect characteristic of insulators. These effects seem to be modulated by changes in chromatin structure.