Fluorophore-assisted carbohydrate electrophoresis in the separation, analysis, and sequencing of carbohydrates

Carbohydrate analysis has traditionally been viewed as a specialty science, performed only in a few well-established laboratories using conventional carbohydrate analysis technology (e.g. NMR, gas chromatography-mass spectroscopy, high-performance liquid chromatography, capillary electrophoresis) combined with the specialized technical training that has been essential for accurate interpretation of the data. This tradition of specialized laboratories is changing, due primarily to an increase in the number of scientists performing routine carbohydrate analysis. As a result, many scientists who are not trained in traditional carbohydrate analytical techniques now need to be able to perform accurate carbohydrate analysis in their own laboratories. This has created a need for technically simple and inexpensive methods of carbohydrate analysis. In this review, we present application vignettes of a technically simple, yet analytically powerful method called fluorophore-assisted carbohydrate electrophoresis (FACE). FACE can be used for performing routine oligosaccharide profiling, monosaccharide analysis, and sequencing of a variety of carbohydrates.     

Economic comparison of calcium fumarate and sodium fumarate production byRhizopus arrhizus

The economics of using Na₂CO₃ rather than CaCO₃ as the neutralizing agent in fumaric acid production byRhizopus arrhizus is investigated and compared with the benzene route. Because sodium fumarate, unlike calcium fumarate, is soluble, downstream processing is simplified by requiring less equipment and no heat, and also allows the reuse of cells. In spite of a fumaric acid productivity (g/L/h) 2.4 x lower than the CaCO₃ case, the Na₂CO₃ alternative with cell reuse has a higher rate of return. However, with the current cost of petroleum, the selling price of fumaric acid from the benzene route is half as much as from an idealized Na₂CO₃ fermentation.     

Geometric approach to the dynamic glass transition

We numerically study the potential energy landscape of a fragile glassy system and find that the dynamic crossover corresponding to the glass transition is actually the effect of an underlying geometric transition caused by the vanishing of the instability index of saddle points of the potential energy. Furthermore, we show that the potential energy barriers connecting local glassy minima increase with decreasing energy of the minima, and we relate this behavior to the fragility of the system. Finally, we analyze the real space structure of activated processes by studying the distribution of particle displacements for local minima connected by simple saddles.     

A note on Meyers' Theorem in

Lower semicontinuity properties of multiple integrals

are studied when may grow linearly with respect to the highest-order derivative, and admissible sequences converge strongly in It is shown that under certain continuity assumptions on convexity, -quasiconvexity or -polyconvexity of

ensures lower semicontinuity. The case where is -quasiconvex remains open except in some very particular cases, such as when

     

A Γ‐convergence result for the two‐gradient theory of phase transitions

The generalization to gradient vector fields of the classical double‐well, singularly perturbed functionals, where W(ξ) = 0 if and only if ξ = A or ξ = B, and A ? B is a rank‐1 matrix, is considered. Under suitable constitutive and growth hypotheses on W, it is shown that I_ε Γ‐converge to where K^* is the (constant) interfacial energy per unit area. © 2002 Wiley Periodicals, Inc.     

Taxol Inclusion Complexes with a Cyclodextrin Dimer: Possibilities to Detoxify Chemotherapeutics and to Target Drugs Specifically to Tumors?

The natural drug, paclitaxel (taxol), is highly effectiveas a tumor chemotherapeuticwith a low probability of inducing chemoresistance,but shows severe toxic side effectsat the therapeutic dose. How can this toxicitybe overcome? Here we report the synthesisof cyclodextrin dimers connected at thesecondary face by amide-bonded aliphatic spacers. The spacer length of one of the dimers referred to asdiβCD(2N-A4C5A4) or dimer 7cmatches the distance between the twobenzoic acid residues of paclitaxel. We investigated the physical inclusion of taxol into this dimer using the TNS-label competition method. Affinity constants with the dimer in comparison to free β-cyclodextrin are found to be of the order of 10⁷ l/mole.When included into the cyclodextrin dimer, the drug shows a considerable time delay of incorporation into human tumor cell cultures (OAT SCLC cells) or a total exclusion from the cells. This is the prerequisite to avoid intoxication of other organs of a patient. Possibilities are discussed to detoxify chemotherapeutics and to target their inclusioncomplexes specifically to tumors using specific biological signals.     

Synthesis of Co2Pt, Co2Pd and MoPd2 mixed-metal clusters with the P–N–P assembling ligands (Ph2P)2NH (dppa) and (Ph2P)2NMe (dppaMe). Crystal structure of [Co2Pt(μ3-CO)(CO)6(μ-dppa)]

Heterometallic triangular platinum–cobalt, palladium–cobalt and palladium–molybdenum clusters stabilized by one or two bridging diphosphine ligands such as Ph₂PNHPPh₂ (dppa) or (Ph₂P)₂NMe (dppaMe) or by mixed ligand sets Ph₂PCH₂PPh₂ (dppm)/dppa have been prepared with the objectives of comparing the stability and properties of the clusters as a function of the short-bite diphosphine ligand used and of the metal carbonyl fragment they contain. Ligand redistribution reactions were observed during the purification of [Co₂Pd(μ₃-CO)(CO)₄(μ-dppa)(μ-dppm)] (4) by column chromatography with the formation of [Co₂Pd(μ₃-CO)(CO)₄(μ-dppm)₂] and the dinuclear complex [(OC)₂ Cl] (5). The latter was independently prepared by reaction of [Pd(dppa-P,P′)₂](BF₄)₂ with Na[Co(CO)₄]. Attempts to directly incorporate the ligand (Ph₂P)₂N(CH₂)₃Si(OMe)₃ (dppaSi) into a cluster or to generate it by N-functionalization of coordinated dppa were unsuccessful, in contrast to results obtained recently with related clusters. The crystal structure of [Co₂Pt(μ₃-CO)(CO)₆(μ-dppa)] (1) has been determined by X-ray diffraction.     

Effects of UVR and UVR-induced cytokines on production of extracellular matrix proteins and proteases by dermal fibroblasts cultured in collagen gels%

Synthesis of extracellular matrix (ECM) proteins and their degradation by matrix metalloproteinases (MMP) are part of the dermal remodeling resulting from chronic exposure of skin to ultraviolet radiation (UVR). We have compared two alternative mechanisms for these responses, namely, a direct mechanism in which UV-B or UV-A is absorbed by fibroblasts and an indirect mechanism in which cytokines, produced in skin in response to UVR, stimulate production of the ECM proteins and MMP. These studies were carried out on human dermal fibroblasts grown in contracted, free-floating 9 day old collagen gels as a dermal equivalent. Synthesis of tropoelastin, collagen, fibrillin, MMP-1, -2, -3 and -9 and tissue inhibitors of metalloproteinases (TIMP)-1 and -2 were measured. Tropoelastin, collagen and fibrillin levels were stable between days 4 and 10, and MMP and TIMP decreased by day 10. Neither UV-B (2.5-50 mJ/cm2) nor UV-A (2-12 J/cm2) altered synthesis of ECM proteins, but UV-A increased MMP-1 and -3 production. Tropoelastin synthesis increased in response to transforming growth factor-beta1 (5 ng/mL) treatment. Both interleukin-1beta and tumor necrosis factor-alpha (10 ng/mL) decreased fibrillin messenger RNA levels but increased MMP-1, -3 and -9 synthesis markedly. Collagen synthesis was not modulated by UV-B, UV-A or cytokine treatment. These results indicate that certain cytokines may have greater effects on production of ECM proteins and MMP than absorption of UV-B and UV-A by fibroblasts grown in dermal equivalents and suggest that the former pathway may play a role in the dermal remodeling in photoaged skin.     

Higher-Order Quasiconvexity Reduces to Quasiconvexity

In this paper it is shown that higher-order quasiconvex functions suitable in the variational treatment of problems involving second derivatives may be extended to the space of all matrices as classical quasiconvex functions. Precisely, it is proved that a smooth strictly 2-quasiconvex function with p-growth at infinity, p>1, is the restriction to symmetric matrices of a 1-quasiconvex function with the same growth. As a consequence, lower-semicontinuity results for second-order variational problems are deduced as corollaries of well-known first-order theorems.