Effect of dietarytrans fatty acids on microsomal enzymes and membranes

Three groups of rats were maintained on diets containing different proportions oftrans fatty acids (0, 18.3 or 36.6% of the total fatty acids) for eight weeks. No differences in body weight were observed among the three groups, but the fat cell size, determined in epididymal fat, differed significantly between the controls and the rats fed diets containingtrans fatty acids. The supernatant obtained by centrifuging homogenates of liver from the rats at 9000×g (S-9 fraction) was used as an activator in a bacterial test for mutagenicity of 2-aminofluorene and aflatoxin B₁ usingSalmonella typhimurium strains TA 98 and TA 100, respectively. The mutagenicities of 2-aminofluorene in strain TA 98 and of aflatoxin B₁ in strain TA 100 were significantly lower with the liver S-9 fraction from rats fed a diet containing 36.6%trans fatty acids than with the liver S-9 fraction from rats fed a control diet with notrans fatty acids.     

Initiation of fractures in rigid PVC pipes by soft particles

Rigid PVC pipes prepared from a particle-free, tin-stabilized formulation were subjected to constant internal pressure tests (16 MPa, 60°C), originally in order to study the scattering in time-to-failure of pipes free from crack-initiating particles. Although many efforts were made to produce pipes free from all possible foreign particles, most failures were initiated by particles. The particles in this case were soft and rubbery, Particles of this kind have previously never been found in any of the several hundred fracture surfaces in lead-stabilized PVC pipes containing calcium carbonate studied in this laboratory. The possible origin of the soft particles is discussed. The results suggest that soft particles represent serious flaws. Besides a full-grown (penetrating) crack, some of the pipes also contained growing, particle-induced cracks. In these cases the penetrating crack always contained the largest particle. The presence of growing cracks in fractured pipes indicates the crack propagation rate in rigid PVC to be rather low at the test temperature and stress level used. Fracture surface morphology and creep thinning of the pipe wall at the point of fracture most likely were strongly affected by physical aging during the test period.     

Abstraction and subsumption in modular verification of C programs

Formal Methods in System Design - The type-theoretic notions of existential abstraction, subtyping, subsumption, and intersection have useful analogues in separation-logic proofs of imperative...     

Synthesis of Novel Pyridine-Carboxylates as Small-Molecule Inhibitors of Human Aspartate/Asparagine-β-Hydroxylase

The human 2-oxoglutarate (2OG)-dependent oxygenase aspartate/asparagine-β-hydroxylase (AspH) is a potential medicinal chemistry target for anticancer therapy. AspH is present on the cell surface of invasive cancer cells and accepts epidermal growth factor-like domain (EGFD) substrates with a noncanonical (i. e., Cys 1–2, 3–4, 5–6) disulfide pattern. We report a concise synthesis of C-3-substituted derivatives of pyridine-2,4-dicarboxylic acid (2,4-PDCA) as 2OG competitors for use in SAR studies on AspH inhibition. AspH inhibition was assayed by using a mass spectrometry-based assay with a stable thioether analogue of a natural EGFD AspH substrate. Certain C-3-substituted 2,4-PDCA derivatives were potent AspH inhibitors, manifesting selectivity over some, but not all, other tested human 2OG oxygenases. The results raise questions about the use of pyridine-carboxylate-related 2OG analogues as selective functional probes for specific 2OG oxygenases, and should aid in the development of AspH inhibitors suitable for in vivo use.     

Influence of Feed Composition and Drying Parameters on the Surface Composition of a Spray-Dried Multicomponent Particle

Surface properties of multicomponent particles produced in spray drying can be controlled by selective accumulation of specific components, which are present in the liquid feed, on the particle surface. Such modification of the surface composition can take place only before a solid shell forms on the particle surface. In this contribution, the influence of the concentration of surface active component on modifications of the surface composition is discussed. Based on results of single-droplet drying simulations, changes in the concentration of the surface active component at the solution-air interface are related to the composition of spray-dried particles.     

Long-Term Effects of Neural Precursor Cell Transplantation on Secondary Injury Processes and Functional Recovery after Severe Cervical Contusion-Compression Spinal Cord Injury

Cervical spinal cord injury (SCI) remains a devastating event without adequate treatment options despite decades of research. In this context, the usefulness of common preclinical SCI models has been criticized. We, therefore, aimed to use a clinically relevant animal model of severe cervical SCI to assess the long-term effects of neural precursor cell (NPC) transplantation on secondary injury processes and functional recovery. To this end, we performed a clip contusion-compression injury at the C6 level in 40 female Wistar rats and a sham surgery in 10 female Wistar rats. NPCs, isolated from the subventricular zone of green fluorescent protein (GFP) expressing transgenic rat embryos, were transplanted ten days after the injury. Functional recovery was assessed weekly, and FluoroGold (FG) retrograde fiber-labeling, as well as manganese-enhanced magnetic resonance imaging (MEMRI), were performed prior to the sacrifice of the animals eight weeks after SCI. After cryosectioning of the spinal cords, immunofluorescence staining was conducted. Results were compared between the treatment groups (NPC, Vehicle, Sham) and statistically analyzed (p < 0.05 was considered significant). Despite the severity of the injury, leading to substantial morbidity and mortality during the experiment, long-term survival of the engrafted NPCs with a predominant differentiation into oligodendrocytes could be observed after eight weeks. While myelination of the injured spinal cord was not significantly improved, NPC treated animals showed a significant increase of intact perilesional motor neurons and preserved spinal tracts compared to untreated Vehicle animals. These findings were associated with enhanced preservation of intact spinal cord tissue. However, reactive astrogliosis and inflammation where not significantly reduced by the NPC-treatment. While differences in the Basso–Beattie–Bresnahan (BBB) score and the Gridwalk test remained insignificant, animals in the NPC group performed significantly better in the more objective CatWalk XT gait analysis, suggesting some beneficial effects of the engrafted NPCs on the functional recovery after severe cervical SCI.     

Estimation of Hamaker Constants of Ceramic Materials from Optical Data Using Lifshitz Theory

The Hamaker constants of eight different ceramic materials, 6H-SiC, tetragonal, partially stabilized ZrO₂ (3% Y₂O₃), β-Si₃N₄, α-Al₂O₃, Y₂O₃, sapphire (single-crystal α-Al₂O₃), MgO, MgAl₂O₄, and fused silica, across air, water, and n -dodecane at room temperature and across silica at 2000 K have been calculated from optical data using the Lifshitz theory. Spectroscopic ellipsometry was used to measure the photon energy dependence of the refractive index, n , and the extinction coefficient, k , in the visible and near-UV range on several important ceramic materials. This relatively simple, nondestructive technique has proved to yield reliable optical data on sintered, polycrystalline materials such as Si₃N₄, SiC, ZrO₂, Al₂O₃, and ZnO. For the other materials, Y₂O₃, sapphire, MgO, MgAl₂O₄, and fused silica, optical data from the literature were used to calculate the Hamaker constants. The calculated Hamaker constants were estimated to be accurate within ±10%.     

Silicon Nitride Colloidal Probe Measurements: Interparticle Forces and the Role of Surface-Segment Interactions in Poly(acrylic acid) Adsorption from Aqueous Solution

Direct measurements of forces between silicon nitride surfaces in the presence of poly(acrylic acid) (PAA) are presented. The force-distance curves were obtained at pH > pH_iep with an atomic force microscopy (AFM) colloidal-probe technique using a novel spherical silicon nitride probe attached to the AFM cantilever. We found that PAA adsorbs onto the negatively charged silicon nitride surface, which results in an increased repulsive surface potential. The steric contribution to the interparticle repulsion is small and the layer conformation remains flat even at high surface potentials or high ionic strength. The general features of the stabilization of ceramic powders with PAA are discussed; we suggest that PAA adsorbs onto silicon nitride by sequential adsorption of neighboring segments ("zipping"), which results in a flat conformation. In contrast, the long-range steric force found in the ZrO₂/PAA system at pH > pH_iep arises because the stretched equilibrium bulk conformation of the highly charged polymer is preserved via the formation of strong, irreversible surface-segment bonds on adsorption.