Patency Outcomes of Aortic Connectors

OBJECTIVE:: Controlled outcome analysis of mechanical aortic connectors for proximal saphenous vein bypass graft anastomosis is lacking. We report the clinical and angiographic outcome of patients receiving the Symmetry aortic connector (St. Jude Medical, Inc St. Paul, MN, US) within a multicenter, prospective, randomized study. METHODS:: Twenty-five patients at 3 study sites received aortic connectors at the time of coronary artery bypass surgery. Protocol-defined angiographic follow-up was completed in 19 of 25 patients (76%) at time-points up to 14 months postoperatively; 32 connector anastomoses were evaluated in these 19 patients. Beating heart surgery was performed in 17 patients, and 2 were performed with cardiopulmonary bypass. Age was 69.7 ± 8.1 year; all patients were males. RESULTS:: The connector anastomosis patency rate was 15.6% (5/32). There were no deaths during the follow-up period. Four patients (21%) suffered myocardial infarction and 2 additional patients (10.5%) required percutaneous coronary interventions; one of who required 3 percutaneous coronary interventions, the other received one percutaneous coronary intervention. CONCLUSIONS:: In this nonrandomized cohort of patients, occlusion rate with Symmetry connectors was significantly greater than anticipated. Patients who have received these connectors during coronary artery bypass surgery may require closer follow-up and evaluation. While the manufacturer has stopped producing this device, there has been no recall of the product, clinical support remains ongoing, and next generation connectors have now been marketed. Consideration should be given to discontinuation of the clinical use of Symmetry connectors.     

The B gene of pea encodes a defective flavonoid 3',5'-hydroxylase, and confers pink flower color

The inheritance of flower color in pea (Pisum sativum) has been studied for more than a century, but many of the genes corresponding to these classical loci remain unidentified. Anthocyanins are the main flower pigments in pea. These are generated via the flavonoid biosynthetic pathway, which has been studied in detail and is well conserved among higher plants. A previous proposal that the Clariroseus (B) gene of pea controls hydroxylation at the 5' position of the B ring of flavonoid precursors of the anthocyanins suggested to us that the gene encoding flavonoid 3',5'-hydroxylase (F3'5'H), the enzyme that hydroxylates the 5' position of the B ring, was a good candidate for B. In order to test this hypothesis, we examined mutants generated by fast neutron bombardment. We found allelic pink-flowered b mutant lines that carried a variety of lesions in an F3'5'H gene, including complete gene deletions. The b mutants lacked glycosylated delphinidin and petunidin, the major pigments present in the progenitor purple-flowered wild-type pea. These results, combined with the finding that the F3'5'H gene cosegregates with b in a genetic mapping population, strongly support our hypothesis that the B gene of pea corresponds to a F3'5'H gene. The molecular characterization of genes involved in pigmentation in pea provides valuable anchor markers for comparative legume genomics and will help to identify differences in anthocyanin biosynthesis that lead to variation in pigmentation among legume species.     

Structural basis of the RNase H1 activity on stereo regular borano phosphonate DNA/RNA hybrids

Numerous DNA chemistries for improving oligodeoxynucleotide (ODN)-based RNA targeting have been explored. The majority of the modifications render the ODN/RNA target insensitive to RNase H1. Borano phosphonate ODN's are among the few modifications that are tolerated by RNase H1. To understand the effect of the stereochemistry of the BH(3) modification on the nucleic acid structure and RNase H1 enzyme activity, we have investigated two DNA/RNA hybrids containing either a R(P) or S(P) BH(3) modification by nuclear magnetic resonance (NMR) spectroscopy. T(M) studies show that the stabilities of R(P) and S(P) modified DNA/RNA hybrids are essentially identical (313.8 K) and similar to that of an unmodified control (312.9 K). The similarity is also reflected in the imino proton spectra. To characterize such similar structures, we used a large number of NMR restraints (including dipolar couplings and backbone torsion angles) to determine structural features that were important for RNase H1 activity. The final NMR structures exhibit excellent agreement with the data (total R(x) values of <6%) with helical properties between those of an A and B helix. Subtle backbone variations are observed in the DNA near the modification, while the RNA strands are relatively unperturbed. In the case of the S(P) modification, for which more perturbations are recorded, a slightly narrower minor groove is also obtained. Unique NOE base contacts localize the S(P) BH(3) group in the major groove while the R(P) BH(3) group points away from the DNA. However, this creates a potential clash of the R(P) BH(3) groups with important RNase H1 residues in a complex, while the S(P) BH(3) groups could be tolerated. We therefore predict that on the basis of our NMR structures a fully R(P) BH(3) DNA/RNA hybrid would not be a substrate for RNase H1.     

Haplotype sharing refines the location of an imprinted quantitative trait locus with major effect on muscle mass to a 250-kb chromosome segment containing the porcine IGF2 gene

We herein describe the fine mapping of an imprinted QTL with major effect on muscle mass that was previously assigned to distal SSC2p in the pig. The proposed approach exploits linkage disequilibrium in combination with QTL genotyping by marker-assisted segregation analysis. By identifying a haplotype shared by all "Q" chromosomes, we map the QTL to an approximately 250-kb chromosome segment containing INS and IGF2 as the only known paternally expressed genes. This considerably reinforces the candidacy of these genes, justifying their detailed analysis.     

A Simple Method for the Reconstitution of Membrane Proteins into Giant Unilamellar Vesicles

A simple method for the reconstitution of membrane protein from submicron proteoliposomes into giant unilamellar vesicles (GUVs) is presented here: This method does not require detergents, fusion peptides or a dehydration step of the membrane protein solution. In a first step, GUVs of lipids were formed by electroformation, purified and concentrated; and in a second step, the concentrated GUV solution was added to a small volume of vesicles or proteoliposomes. Material transfer from submicron vesicles and proteoliposomes to GUVs occurred spontaneously and was characterized with fluorescent microscopy and patch-clamp recordings. As a functional test, the voltage-dependent, anion-selective channel protein was reconstituted into GUVs, and its electrophysiological activity was monitored with the patch clamp. This method is versatile since it is independent of the presence of the protein, as demonstrated by the fusion of fluorescently labeled submicron vesicles and proteoliposomes with GUVs.     

Phage display as a powerful tool to engineer protease inhibitors

Since its introduction by Georges Smith some 25 years ago, phage display has proved to be a powerful molecular technique for selecting proteins with desired biological properties from huge libraries. Early on, various protease inhibitor scaffolds were displayed at the surface of filamentous phages to select new inhibitors with shifted specificities and enhanced affinities towards one or more target protease(s). The past two decades have seen a number of natural protease inhibitors subjected to phage display, mostly to shift and increase their inhibitory specificity, but also to explore the molecular mechanisms by which they interact with their cognate enzymes with low or very high selectivity. This review focuses on the major uses of phage display in the field of protein protease inhibitors. The exquisite molecular mechanisms by which natural protease inhibitors prevent unwanted or excessive proteolysis in cells and tissues are also examined along with some of the general principles underlying the way phage display is applied to these molecules.     

Spine and dine: A key defensive trait promotes ecological success in spiny ants

A key focus of ecologists is explaining the origin and maintenance of morphological diversity and its association with ecological success. We investigate potential benefits and costs of a common and varied morphological trait, cuticular spines, for foraging behavior, interspecific competition, and predator–prey interactions in naturally co‐occurring spiny ants (Hymenoptera: Formicidae: Polyrhachis) in an experimental setting. We expect that a defensive trait like spines might be associated with more conspicuous foraging, a greater number of workers sent out to forage, and potentially increased competitive ability. Alternatively, consistent with the ecological trade‐off hypothesis, we expect that investment in spines for antipredator defense might be negatively correlated with these other ecological traits. We find little evidence for any costs to ecological traits, instead finding that species with longer spines either outperform or do not differ from species with shorter spines for all tested metrics, including resource discovery rate and foraging effort as well as competitive ability and antipredator defense. Spines appear to confer broad antipredator benefits and serve as a form of defense with undetectable costs to key ecological abilities like resource foraging and competitive ability, providing an explanation for both the ecological success of the study genus and the large number of evolutionary origins of this trait across all ants. This study also provides a rare quantitative empirical test of ecological effects related to a morphological trait in ants.     

Scavenger receptor BI boosts hepatocyte permissiveness to Plasmodium infection

Infection of hepatocytes by Plasmodium falciparum sporozoites requires the host tetraspanin CD81. CD81 is also predicted to be a coreceptor, along with scavenger receptor BI (SR-BI), for hepatitis C virus. Using SR-BI-knockout, SR-BI-hypomorphic and SR-BI-transgenic primary hepatocytes, as well as specific SR-BI-blocking antibodies, we demonstrate that SR-BI significantly boosts hepatocyte permissiveness to P. falciparum, P. yoelii, and P. berghei entry and promotes parasite development. We show that SR-BI, but not the low-density lipoprotein receptor, acts as a major cholesterol provider that enhances Plasmodium infection. SR-BI regulates the organization of CD81 at the plasma membrane, mediating an arrangement that is highly permissive to penetration by sporozoites. Concomitantly, SR-BI upregulates the expression of the liver fatty-acid carrier L-FABP, a protein implicated in Plasmodium liver-stage maturation. These findings establish the mechanistic basis of the CD81-dependent Plasmodium sporozoite invasion pathway.