Apoptosis in interface membranes of aseptically loose total hip arthroplasty

The terminal events leading to periprosthetic osteolysis are multifactorial in nature and modulation of this process after the stage of osteolytic mediator release has been futile. Recently, the demonstration of the ability of bisphosphonates to inhibit bone resorption that is mediated by particle-stimulated macrophages and their induction of osteoclast apoptosis suggests a potent area for modulation of osteolysis at the prosthesis-bone interface. The purpose of this study was to determine the mode of cell death that occurs at the osteolytic interface of failed total hip arthroplasty (THA). TUNEL staining, DNA laddering, and immunodetection of poly(ADP-ribose)polymerase (PARP) protein were used to identify the presence of apoptosis in interface membranes from 25 patients aged 28–88 years old (mean, 58 years) harvested at the time of hip revision surgery. Our results demonstrated positive TUNEL stain in 100% of specimens with an average 37% of cells (range 12–60%) positively stained for TUNEL whereas less than 8% of control tissue cells showed positive staining. DNA laddering, a characteristic feature of apoptotic cells, was observed in 82% (28/34) of specimens studied at both the acetabular and femoral side of aseptically loose THAs. No laddering was observed in control tissues. Finally, using Western blot analysis, we observed the appearance of the 89 kDa PARP fragment associated with apoptosis in 92% of specimens (30/33). Our results demonstrate the presence of apoptotic cell death in interface membranes of THAs suggesting that apoptosis-related events are indeed associated with periprosthetic osteolysis and could serve as a specific target point for therapeutic modulation. © 2001 Kluwer Academic Publishers     

Synchronous Control of a Static AC Induction Motor Drive

Conventional methods of controlling an induction motor utilize regulation of stator current and motor slip frequency in order to maintain system stability. This control strategy requires a shaft speed feedback and fast-response current regulation. An alternative method of controlling an induction motor is presented which achieves the necessary system stabilization by controlling only the motor frequency. The control inherently regulates the motor torque angle by properly adjusting the phase of the converter firing signals. By synchronizing the inverter firing pulses to the motor back electromotive force (EMF) possible adverse inverter operating modes are avoided. The concept of synchronous control eliminates the preprogrammed functional relations previously required and allows the control to adapt to any desired motor flux level. Any desired outer regulating loop can be incorporated to form a fast-response wide-range ac drive system.     

Simulation of deformation and lifetime behavior of a fcc single crystal superalloy at high temperature under low-cycle fatigue loading

This work deals with the formulation of a three-dimensional crystallographic time-incremental lifetime rule for face-centered cubic (fcc) single crystals used for gas-turbine blade applications. The damage contribution rate of each slip system to the total damage is governed by the current values of the resolved shear stress and the slip rate on the corresponding slip system. The damage rule is combined with a crystallographic viscoplastic deformation model. For the nickel-base single-crystal superalloy CMSX4 at 950 °C, various strain- and stress-controlled uniaxial cyclic tests with and without hold-times can be described for different crystal orientations by one set of material parameters. For verification, simulation results for a single-crystal specimen with a notch have been compared with corresponding experimental results. The predicted lifetime is within the factor of two of the measured one.     

Release of fluorescent markers from phase‐separated gelatin‐maltodextrin hydrogels

Genipin‐crosslinked gelatin‐maltodextrin phase‐separated hydrogels consisting of gelatin‐continuous or bicontinuous microstructures were developed to regulate swelling and release behavior of four fluorescent markers of varying molecular weights [(fluorescein (332 Da) and FITC‐dextrans (FD) (4000–250,000 Da)]. Bicontinuous hydrogels showed significantly greater swelling than gelatin‐continuous hydrogels under all conditions (at pH 1.5 and 7.4 and three genipin/gelatin crosslinking ratios) (P < 0.05). With both microstructures, fluorescein showed the largest release rate and total release followed by FD 4000 Da, FD 40,000 Da, and FD 250,000 Da (P < 0.05). Marker molecular weight, pH, and crosslink ratio all affected the rate and amount of release. The mode of transport for the solvent and all markers was Fickian or slightly anomalous, with diffusional exponent (n) values ranging from 0.35 to 0.64. These results demonstrated that with the proper combination of crosslink density, solvent pH, and microstructure, hydrogels with a specified swelling behavior may be developed. This, coupled with a marker of appropriate size, can lead to controllable levels and rates of release. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Challenges in Catalytic Manufacture of Renewable Pyrrolidinones from Fermentation Derived Succinate

Fermentation derived succinic acid ammonium salt is an ideal precursor for manufacture of renewable N-methyl pyrrolidinone (NMP) or 2-pyrrolidinone (2P) via heterogeneous catalysis. However, there are many challenges to making this a practical reality. Chief among the challenges is avoiding catalyst poisoning by fermentation by- and co-products. Battelle/Pacific Northwest National Laboratory have developed an effective technology strategy for this purpose. The technology is a combination of purely thermal processing, followed by simple catalytic hydrogenation that together avoids catalyst poisoning from fermentation impurities and provides high selectivity and yields of NMP or 2P.

     

Defined Conjugation of Glycans to the Lysines of CRM197 Guided by their Reactivity Mapping

Systematic characterisation of the reactivity of the lysine moieties in CRM₁₉₇ towards N‐hydroxysuccinimide linkers bearing alkynes or azides is described. This involves two‐step conjugation of various glycans to CRM₁₉₇ by click chemistry in a well‐defined manner. By semiquantitative LC‐MS/MS analysis of proteolytic digests of the conjugates formed, the reactivity of lysine residues in the protein was mapped and ranked. Computational analysis of the solvent accessibility of each lysine residue (based on the CRM₁₉₇ crystal structure) established a correlation between reactivity and surface exposure. By this approach, conjugation involving lysine residues (normally a random process) can be controlled. It enables the preparation of lysine‐mediated glycoconjugates with improved batch‐to‐batch reproducibility, thereby producing neo‐glycoconjugates with more‐consistent biological activity.     

On the modeling and optimization of UV‐curable fluoro‐siloxane formulations and their solvent absorption and adhesion properties

A screening study was performed on a family of UV‐curable fluoro‐silicone polymers designed to coat aluminum. Solvent durability, adhesion, dimensional stability, and thermal oxidative stability were important physical parameters to control. An XVERT mixture experimental design was used to model the behavior of selected polymer formulations. A calibrated linear model showed excellent correlation with experimental data. The coefficients from this model were then used to predict and optimize the responses of the polymer formulations to specific requirements. It was shown that percent fluorination was a strong influence on the amount of solvent absorption and the level of thermal oxidative stability, while the amount of hydrocarbon‐based alcohol was shown to be necessary for adhesion to aluminum and a post cure polyurethane top coat. POLYM. ENG. SCI., 59:1678–1687 2019. © 2019 Society of Plastics Engineers     

Pathways for fatty acid elongation and desaturation in Neurospora crassa

Neurospora crassa incorporated exogenous deuterated palmitate (16∶0) and ¹⁴C-labeled oleate (18∶1^Δ9) into cell lipids. Of the exogenous 18∶1^Δ9 incorporated, 59% was desaturated to 18∶2^Δ9,12 and 18∶3^Δ9,12,15. Of the exogenous 16∶0 incorporated, 20% was elongated to 18∶0, while 37% was elongated and desaturated into 18∶1^Δ9, 18∶2^Δ9,12, and 18∶3^Δ9,12,15. The mass of unsaturated fatty acids in phospholipid and triacylglycerol is 12 times greater than the mass of 18∶0. Deuterium label incorporation in unsaturated fatty acids is only twofold greater than in 18∶0, indicating a sixfold preferential use of 16∶0 for saturated fatty acid synthesis. These results indicate that the release of 16∶0 from fatty acid synthase is a key control point that influences fatty acid composition in Neurospora.     

Novel Simple Conjugation Chemistries for Decoration of GMMA with Heterologous Antigens

Outer Membrane Vesicles (OMV) constitute a promising platform for the development of efficient vaccines. OMV can be decorated with heterologous antigens (proteins or polysaccharides), becoming attractive novel carriers for the development of multicomponent vaccines. Chemical conjugation represents a tool for linking antigens, also from phylogenetically distant pathogens, to OMV. Here we develop two simple and widely applicable conjugation chemistries targeting proteins or lipopolysaccharides on the surface of Generalized Modules for Membrane Antigens (GMMA), OMV spontaneously released from Gram-negative bacteria mutated to increase vesicle yield and reduce potential reactogenicity. A Design of Experiment approach was used to identify optimal conditions for GMMA activation before conjugation, resulting in consistent processes and ensuring conjugation efficiency. Conjugates produced by both chemistries induced strong humoral response against the heterologous antigen and GMMA. Additionally, the use of the two orthogonal chemistries allowed to control the linkage of two different antigens on the same GMMA particle. This work supports the further advancement of this novel platform with great potential for the design of effective vaccines.