AbsorbaSeal™ 5.6.7F vascular closure device: A good laboratory practice chronic study evaluating safety and efficacy in a healthy porcine model.

OBJECTIVES: Vascular closure devices (VCDs) are widely used for arteriotomy closure after percutaneous catheter-based procedures. In comparison to manual compression, VCDs have been associated with shorter time to hemostasis, shorter time to ambulation, and also decreased length of stay. Complexity of deployment, lack of immediate hemostasis, and residual deformity of the arterial wall remain as limitations of current VCDs. The aim of this study was to investigate the AbsorbaSeal™ 5.6.7F vascular closure device, a novel, completely bioabsorbable, intuitive, and easy to use VCD which uses a compressive, "sandwich"-type design comprising a low profile intravascular distal seal and gasket and an extravascular floating foot and proximal seal, in an open infrarenal aortic swine model. METHODS: Eight fully heparinized swine at a good laboratory practices facility underwent AbsorbaSeal™ 5.6.7F VCD closure of three 6F arteriotomies each in the proximal, mid, and distal infrarenal aorta. Two swine underwent harvest at each of four time cohorts: 30, 60, 90, and 120 days. Acute and chronic procedural safety and efficacy, as well as target site vascular remodeling over time, were the primary outcomes evaluated. Secondary outcome measures included local and systemic inflammatory responses, end-organ tissue analysis, and device-related complications through the follow-up periods. Histopathological evaluation was performed by a blinded pathologist. Standard statistical methods were used. RESULTS: In deployment of 24 AbsorbaSeal™ 5.6.7F VCDs, there were no device-related complications or mortalities. All deployments resulted in rapid arteriotomy seal (100% deployment success), with a mean time to hemostasis (cessation of arterial flow) of 21.5 s (median: 6.5 s) across a mean activated clotting time (ACT) of 356 s. Twenty of the 24 implant sites (83%) attained complete hemostasis within 20 s. Immediate post-implant and pre-termination angiographies at all time points were performed of all swine which demonstrated normal aortic appearance and tissue structure and normal downstream vascular beds. At 30 days, each implant's intravascular distal seal and gasket were removed from the circulation and completely covered with a smooth neointimal layer. Minimal inflammation and no intimal or luminal thrombus were observed at any site at every time point. CONCLUSIONS: AbsorbaSeal™ 5.6.7F is a safe, effective, and secure VCD that demonstrates rapid hemostasis in a fully heparinized open aortic porcine model. Removal from circulation and complete coverage of the intravascular distal seal and gasket with neointima occurred within 30 days post-implant. Natural transmural vessel healing from the arteriotomy itself with minimal inflammation was noted for each implant at every time point.

The nature and origin of interstellar diamond.

Microscopic diamond was recently discovered in oxidized acid residues from several carbonaceous chondrite meteorites (for example, the C delta component of the Allende meteorite). Some of the reported properties of C delta seem in conflict with those expected of diamond. Here we present high spatial resolution analytical data which may help to explain such results. The C delta diamond is an extremely fine-grained (0.5-10 nm) single-phase material, but surface and interfacial carbon atoms, which may comprise as much as 25% of the total, impart an 'amorphous' character to some spectral data. These data support the proposed high-pressure conversion of amorphous carbon and graphite into diamonds due to grain-grain collisions in the interstellar medium although a low-pressure mechanism of formation cannot be ruled out.

Deuterium exchange during acid-demineralisation.

Isotopic analyses of residues prepared by demineralisation of the Murchison meteorite using D-labelled reagents provide evidence for measurable exchange of H-isotopes between residue and reagents. Precise quantification of this effect is precluded by substantial inhomogeneity of the meteoritic organic matter. A conservative estimate of the degree of exchange is 3 to 5% of the H pyrolysable as H2O. This could affect the shape of the curve defining D-release as a function of temperature, but does not change conclusions previously drawn concerning the nature of the bulk D-enrichment of insoluble organic matter in meteorites.

Isotopic characterisation of kerogen-like material in the Murchison carbonaceous chondrite.

Isotopic data for C, H and N in acid-resistant residues from carbonaceous chondrites show substantial variability during stepwise pyrolysis and/or combustion. After subtraction of contributions due apparently to inorganic C grains, of probably circumstellar origin, considerable isotopic variability remains, attributable to the kerogen-like organic fraction. That variability may be interpreted in terms of three or four distinct components, based on C, H and N isotopes. The relative proportions of those components vary significantly from sample to sample. The different isotopic components are tentatively identified in terms of specific chemical/structural moieties within the kerogen-like material. This combination of chemical, structural and isotopic information suggests a complex for meteoritic organic matter. At least three components within the organic populations as a whole still carry a signature of apparently interstellar D-enrichment. Part, at least, of the interstellar carrier consisted of reactive entities, not solely polymers.