Analysis of a homologous series of non-reducing oligosaccharides from Arnica montana L. Roots

The oligosaccharide component compositions of a series of non-reducing oligosaccharides extracted from the roots of Arnica montana L. has been determined by gel permeation chromatography (g.p.c.). The range of oligosaccharides present was found to extend beyond the octasaccharide previously reported. with 16% to 19% of the oligosaccharides having a degree of polymerisation of between 11 and 19 and almost 3% having a degree of polymerisation greater than 20. The chromatographic behaviour of this series of oligosaccharides is compared with that observed for series of D-gluco-oligosaccharides.     

Heat transfer and pressure drop in a new type of corrugated channels

An experimental investigation of heat transfer and pressure drop from a new type of corrugated channels is presented. The investigation has been carried out for Reynolds numbers in the range of $\text{800 <}\text{Re}\text{< 5000}$ for one corrugated and one smooth channel. It is found that the heat transfer from the corrugated channel is up to 3.5 times higher than for the smooth one. The pressure drop is however large (5 – 6 times the value of a smooth channel) and it is suggested that the corrugation height and length should be altered in order to balance the increases in heat transfer and pressure drop.     

Identifying a putative common binding site shared by substance P receptor and an anti-substance P monoclonal antibody

Substance P G-protein coupled receptor and the antigen recognitionsite of a monoclonal antibody raised against substance P sharea stretch of five contiguous identical amino acids. This observationprompted us to build an atomic model of both the receptor andthe antibody and to analyse their common features. In particular,we report here that a pocket of similar size and compositionis present in both proteins, strongly suggesting a similarityin the mode of binding of both macromolecules to substance P.From the analysis of our models, the available data on the modeof binding of the antibody to substance P and recent data onsubstance P receptor mutants, we concluded that the pocket isvery likely to be involved in binding of the C-terminal 'messagesequence' of the tachykinin. This allowed us to suggest specificsite-directed mutants of the receptor which should shed somelight on the mechanism of peptide recognition by G-protein coupledreceptors.     

Macroscopic model for multispecies ion-exchange kinetics

A model for multispecies ion-exchange kinetics based on the Nernst-Planck equation is suggested. It is analyzed in comparison with the “locally-determinate” model described by Hwang and Helfferich [1]. The model makes possible simple computation. The conditions for the occurrence of unusual kinetic curves with a maximum are clarified. The proposed model is developed for different types of kinetic problems and verified by the experimental investigation of a kinetics in ternary systems.     

Tobramycin-EDTA conjugate: a noninnocent affinity-cleaving reagent

The design, synthesis, and ribozyme inhibitory activity of a novel EDTA-aminoglycoside conjugate are reported. This affinity cleaving reagent is a noninnocent RNA binder: its RNA affinity, judged by its ability to inhibit the hammerhead ribozyme HH16, is different than the parent natural product and is markedly dependent on the oxidation state of the chelated metal ion.     

Determination of porous glass surface free energy components from contact angles

The contact angles of water drops and diiodomethane drops on pellets made of controlled porosity glasses have been measured. The surface of the glasses was modified by thermal treatment at 873 K which led to an increase in the surface concentration of boron atoms. Glass modified with Carbowax 20M (polyethylene glycol) and fully hydroxylated glass have also been studied. Using the measured contact angles and modified Young equation, the dispersion and nondispersion components of the glass surface free energy have been calculated. The values show that with increasing heating time (increasing surface density of boron atoms) an increase in the surface polarity takes place. However, the polarity of the same samples decreases after treatment with Carbowax, increasingly so with higher boron atom concentrations.     

Solid state reactions in the Fe2O3-CaCO3-In2O3 system

The kinetics of solid-state reactions of powdered reactants were investigated by X-ray and by differential thermogravimetry in a magnetic field. Measurements revealed mutual diffusion of the Fe³⁺ and In³⁺ ions in the Fe₂O₃-In₂O₃ system heat treated for 3 h at 700 to 1400° C. Diffusion of indium into the Fe₂O₃ lattice caused a shift of the Curie temperature of the antiferromagnetic iron oxide towards lower temperatures. Only Caln₂O₄ was found between CaCO₃ and In₂O₃ up to 1400° C. Also, in the Fe₂O₃-CaCO₃-In₂O₃in system, the reaction started with the mutual diffusion of iron and indium and the forming of CaFe₂O₄. End-products were the magnetic -Ca₄Fe₁₄O₂₅ and CaFe₄O₇, and the non-magnetic CaFe₅O₇, depending on the In³⁺ concentration. Indium stabilized the magnetic calcium-iron oxide structures, shifting their Curie temperatures towards lower values.     

Usable optimistic fair exchange

Fairly exchanging digital content is an everyday problem. It has been shown that fair exchange cannot be achieved without a trusted third party (called the Arbiter). Yet, even with a trusted party, it is still non-trivial to come up with an efficient solution, especially one that can be used in a p2p file sharing system with a high volume of data exchanged.We provide an efficient optimistic fair exchange mechanism for bartering digital files, where receiving a payment in return for a file (buying) is also considered fair. The exchange is optimistic, removing the need for the Arbiter’s involvement unless a dispute occurs. While the previous solutions employ costly cryptographic primitives for every file or block exchanged, our protocol employs them only once per peer, therefore achieving an O(n) efficiency improvement when n blocks are exchanged between two peers. Our protocol uses very efficient cryptography, making it perfectly suitable for a p-2-p file sharing system where tens of peers exchange thousands of blocks and they do not know beforehand which ones they will end up exchanging. Therefore, our system yields up to one-to-two orders of magnitude improvement in terms of both computation and communication (40 s vs. 42 min, 1.6 MB vs. 200 MB). Thus, for the first time, a provably secure (and privacy-respecting when payments are made using e-cash) fair exchange protocol can be used in real bartering applications (e.g., BitTorrent) [14] without sacrificing performance.     

Genetic Insight into the Domain Structure and Functions of Dicer-Type Ribonucleases

Ribonuclease Dicer belongs to the family of RNase III endoribonucleases, the enzymes that specifically hydrolyze phosphodiester bonds found in double-stranded regions of RNAs. Dicer enzymes are mostly known for their essential role in the biogenesis of small regulatory RNAs. A typical Dicer-type RNase consists of a helicase domain, a domain of unknown function (DUF283), a PAZ (Piwi-Argonaute-Zwille) domain, two RNase III domains, and a double-stranded RNA binding domain; however, the domain composition of Dicers varies among species. Dicer and its homologues developed only in eukaryotes; nevertheless, the two enzymatic domains of Dicer, helicase and RNase III, display high sequence similarity to their prokaryotic orthologs. Evolutionary studies indicate that a combination of the helicase and RNase III domains in a single protein is a eukaryotic signature and is supposed to be one of the critical events that triggered the consolidation of the eukaryotic RNA interference. In this review, we provide the genetic insight into the domain organization and structure of Dicer proteins found in vertebrate and invertebrate animals, plants and fungi. We also discuss, in the context of the individual domains, domain deletion variants and partner proteins, a variety of Dicers’ functions not only related to small RNA biogenesis pathways.     

Role of HMOX1 Promoter Genetic Variants in Chemoresistance and Chemotherapy Induced Neutropenia in Children with Acute Lymphoblastic Leukemia

Whilst the survival rates of childhood acute lymphoblastic leukemia (ALL) have increased remarkably over the last decades, the therapy resistance and toxicity are still the major causes of treatment failure. It was shown that overexpression of heme oxygenase-1 (HO-1) promotes proliferation and chemoresistance of cancer cells. In humans, the HO-1 gene (HMOX1) expression is modulated by two polymorphisms in the promoter region: (GT)n-length polymorphism and single-nucleotide polymorphism (SNP) A(−413)T, with short GT repeat sequences and 413-A variants linked to an increased HO-1 inducibility. We found that the short alleles are significantly more frequent in ALL patients in comparison to the control group, and that their presence may be associated with a higher risk of treatment failure, reflecting the role of HO-1 in chemoresistance. We also observed that the presence of short alleles may predispose to develop chemotherapy-induced neutropenia. In case of SNP, the 413-T variant co-segregated with short or long alleles, while 413-A almost selectively co-segregated with long alleles, hence it is not possible to determine if SNPs are actually of phenotypic significance. Our results suggest that HO-1 can be a potential target to overcome the treatment failure in ALL patients.