VUV 157 nm laser ablation of composite structures

We report on the laser ablation of composite prismatic structures using a vacuum ultraviolet (VUV) 157 nm F 2 laser. Polycarbonate and CR-39 substrates have been intentionally seeded with silver wires and silicon carbide whiskers respectively. The seed particles remain attached to the underlying substrate after laser ablation, forming composite silver-polycarbonate and silicon carbide-CR-39 interfaces. Strong optical absorption at 157 nm in the polymeric substrates allows precise control over the depth between the base of the substrate and composite interface. The surface roughness of the as-received seed particles has a significant effect on the final surface quality of the ablated structures. The textured surface on the silicon carbide whiskers is resolved on the walls of the ablated structures. This is in contrast to the composite structures formed using silver wires, which have a comparatively smoother surface. © 2010 Springer-Verlag

Contributions of Gene Marking to Cell and Gene Therapies

The first human genetic modification studies used replication-incompetent integrating vector vectors to introduce marker genes into T lymphocytes and subsequently into hematopoietic stem cells. Such studies have provided numerous insights into the biology of hematopoiesis and immune reconstitution and contributed to clinical development of gene and cell therapies. Tracking of hematopoietic reconstitution and analysis of the origin of residual malignant disease after hematopoietic transplantation has been possible via gene marking. Introduction of selectable marker genes has enabled preselection of specific T-cell populations for tumor and viral immunotherapy and reduced the threat of graft-versus-host disease, improving the survival of patients after allogeneic marrow transplantation. Marking studies in humans, murine xenografts, and large animals have helped optimize conditions for gene transfer into CD34+ hematopoietic progenitors, contributing to the achievement of gene transfer efficiencies sufficient for clinical benefit in several serious genetic diseases such as X-linked severe combined immunodeficiency and adrenoleukodystropy. When adverse events linked to insertional mutagenesis arose in clinical gene therapy trials for inherited immunodeficiencies, additional animal studies using gene-marking vectors have greatly increased our understanding of genotoxicity. The knowledge gained from these studies is being translated into new vector designs and clinical protocols, which we hope will continue to improve the efficiency, effectiveness and safety of these promising therapeutic approaches