Induced Remodeling of Porcine Tendons to Human Anterior Cruciate Ligaments by alpha-GAL Epitope Removal and Partial Cross-Linking

This review describes a novel method developed for processing porcine tendon and other ligament implants that enables in situ remodeling into autologous ligaments in humans. The method differs from methods using extracellular matrices (ECMs) that provide postoperative orthobiological support (i.e., augmentation grafts) for healing of injured ligaments, in that the porcine bone-patellar-tendon-bone itself serves as the graft replacing ruptured anterior cruciate ligament (ACL). The method allows for gradual remodeling of porcine tendon into autologous human ACL while maintaining the biomechanical integrity. The method was first evaluated in a preclinical model of monkeys and subsequently in patients. The method overcomes detrimental effects of the natural anti-Gal antibody and harnesses anti-non-gal antibodies for the remodeling process in two steps: Step 1. Elimination of alpha-gal epitopes-this epitope that is abundant in pigs (as in other nonprimate mammals) binds the natural anti-Gal antibody, which is the most abundant natural antibody in humans. This interaction, which can induce fast resorption of the porcine implant, is avoided by enzymatic elimination of alpha-gal epitopes from the implant with recombinant alpha-galactosidase. Step 2. Partial cross-linking of porcine tendon with glutaraldehyde-this cross-linking generates covalent bonds in the ECM, which slow infiltration of macrophages into the implant. Anti-non-gal antibodies are produced in recipients against the multiple porcine antigenic proteins and proteoglycans because of sequence differences between human and porcine homologous proteins. Anti-non-gal antibodies bind to the implant ECM, recruit macrophages, and induce the implant destruction by directing proteolytic activity of macrophages. Partial cross-linking of the tendon ECM decreases the extent of macrophage infiltration and degradation of the implant and enables concomitant infiltration of fibroblasts that follow the infiltrating macrophages. These fibroblasts align with the implant collagen fibers and secrete their own collagen and other ECM proteins, which gradually remodel the porcine tendon into human ACL. This ligamentization process lasts approximately 2 years and the biomechanical integrity of the graft is maintained throughout the whole period. These studies are the first, and so far the only, to demonstrate remodeling of porcine tendon implants into permanently functional autologous ACL in humans

Charge transfer reactions in nematic liquid crystals

Ultrafast transient absorption studies of intramolecular photoinduced charge separation and thermal charge recombination were carried out on a molecule consisting of a 4-(N-pyrrolidino)naphthalene-1,8-imide donor (PNI) covalently attached to a pyromellitimide acceptor (PI) dissolved in the liquid crystal 4{prime}-(n-pentyl)-4-cyanobiphenyl (5CB). The temperature dependencies of the charge separation and recombination rates were obtained at temperatures above the nematic-isotropic phase transition of 5CB, where ordered microdomains exist and scattering of visible light by these domains is absent. The authors show that excited state charge separation is dominated by molecular reorientation of 5CB perpendicular to the director within the liquid crystal microdomains. They also show that charge recombination is adiabatic and is controlled by the comparatively slow collective reorientation of the liquid crystal microdomains relative to the orientation of PNI{sup +}-PI{sup {minus}}. They also report the results of time resolved electron paramagnetic resonance (TREPR) studies of photoinduced charge separation in a series of supramolecular compounds dissolved in oriented liquid crystal solvents. These studies permit the determination of the radical pair energy levels as the solvent reorganization energy increases from the low temperature crystalline phase, through the soft glass phase, to the nematic phase of the liquid crystal

Alteration of the interconversion of pyruvate and malate in the plastid or cytosol of ripening tomato fruit invokes diverse consequences on sugar but similar effects on cellular organic Acid, metabolism, and transitory starch accumulation

The aim of this work was to investigate the effect of decreased cytosolic phosphoenolpyruvate carboxykinase (PEPCK) and plastidic NADP-dependent malic enzyme (NADP-ME) on tomato (Solanum lycopersicum) ripening. Transgenic tomato plants with strongly reduced levels of PEPCK and plastidic NADP-ME were generated by RNA interference gene silencing under the control of a ripening-specific E8 promoter. While these genetic modifications had relatively little effect on the total fruit yield and size, they had strong effects in fruit metabolism. Both transformants were characterized by lower levels of starch at breaker stage. Analysis of the activation state of ADP-glucose pyrophosphorylase correlated with the decrease of starch in both transformats, which suggest that is due to an altered cellular redox status. Moreover, metabolic profiling and feeding experiments involving positional labelled glucoses of fruits lacking in plastidic NADP-malic enzyme and cytosolic PEPCK activities revealed differential changes in overall respiration rates and tricarboxylic acid (TCA) cycle flux. Inactivation of cytosolic PEPCK affected the respiration rate which suggests that excess of oxaloacetate OAA is converted to aspartate and reintroduced in the TCA via 2-oxoglutarate/glutamate. On the other hand, the plastidic NADP-malic enzyme antisense lines were characterized by no changes in respiration rates and TCA cycle flux and together with an increase of pyruvate kinase and phosphoenolpyruvate carboxylase activities indicates that pyruvate is supply through these enzymes to the TCA cycle. These results are discussed in the context of current models of the importance of malate during tomato fruit ripening

Using a newly developed long-period grating filter to improve the timing tolerance of a 320 Gb/s demultiplexer

A 0.8 ps flat top pulse is generated using a long-period fibre grating and used as control pulse for the first time in a 320 Gb/s demultiplexer. The effect is an increased error-free timing tolerance.</p

1/z-renormalization of the mean-field behavior of the dipole-coupled singlet-singlet system HoF_3

The two main characteristics of the holmium ions in HoF_3 are that their local electronic properties are dominated by two singlet states lying well below the remaining 4f-levels, and that the classical dipole-coupling is an order of magnitude larger than any other two-ion interactions between the Ho-moments. This combination makes the system particularly suitable for testing refinements of the mean-field theory. There are four Ho-ions per unit cell and the hyperfine coupled electronic and nuclear moments on the Ho-ions order in a ferrimagnetic structure at T_C=0.53 K. The corrections to the mean-field behavior of holmium triflouride, both in the paramagnetic and ferrimagnetic phase, have been calculated to first order in the high-density 1/z-expansion. The effective medium theory, which includes the effects of the single-site fluctuations, leads to a substantially improved description of the magnetic properties of HoF_3, in comparison with that based on the mean-field approximation.Comment: 26pp, plain-TeX, JJ

640 Gb/s timing tolerant demultiplexing using a cascaded long-period fiber grating pulse shaper

An SMF inscribed with two polarization independent long-period gratings is used for sub-picosecond pulse shaping and validated in a 640 Gb/s data demultiplexing experiment, providing a jitter tolerance of 510 fs.</p

Identification of RPS14 as a 5q- syndrome gene by RNA interference screen

Somatic chromosomal deletions in cancer are thought to indicate the location of tumor suppressor genes, whereby complete loss of gene function occurs through biallelic deletion, point mutation, or epigenetic silencing, thus fulfilling Knudson's two-hit hypothesis.1 In many recurrent deletions, however, such biallelic inactivation has not been found. One prominent example is the 5q- syndrome, a subtype of myelodysplastic syndrome (MDS) characterized by a defect in erythroid differentiation.2 Here, we describe an RNA interference (RNAi)-based approach to discovery of the 5q- disease gene. We find that partial loss of function of the ribosomal protein RPS14 phenocopies the disease in normal hematopoietic progenitor cells, and moreover that forced expression of RPS14 rescues the disease phenotype in patient-derived bone marrow cells. In addition, we identified a block in the processing of pre-rRNA in RPS14 deficient cells that is highly analogous to the functional defect in Diamond Blackfan Anemia, linking the molecular pathophysiology of the 5q- syndrome to a congenital bone marrow failure syndrome. These results indicate that the 5q- syndrome is caused by a defect in ribosomal protein function, and suggests that RNAi screening is an effective strategy for identifying causal haploinsufficiency disease genes