Authors:O. I. Vlaskina, A. S. Izmailovich, and V. I. Tsirelnikov
For studying the thermal disproportionation and interaction processes of niobium bromides in the NbBr5-Nb system thermoanalytical and tensimetric methods were employed. The study revealed that the reduction of niobium pentabromide by metallic niobium starts at 257°C and leads to the formation of niobium tetrabromide. The temperature limits of the existence of bromides of niobium in lower oxidation states were determined.
Authors:G. Puglisi, M. Fresta, C. Ventura, G. Mazzone, and M. Vandelli
Dipalmitoylphosphatidylcholine (DPPC) liposomes were employed as membrane models for the investigation of the interaction
occurring between methotrexate (MTX) and bilayer lipid matrix. Liposomes were obtained by hydrating a lipid film with 50 mM
Tris buffer (pH 7.4). The differential scanning calorimetry (DSC) evaluation of the thermotropic parameters associated with the phase transitions
of DPPC liposomes gave useful information about the kind of drug-membrane interaction. The results showed an electrostatic
interaction taking place with the negatively charged molecules of MTX and the phosphorylcholine head groups, constituting
the outer part of DPPC bilayers. No interaction with the hydrophobic phospholipid bilayer domains was detected, revealing
a poor capability of MTX to cross through lipid membranes to reach the interior compartment of a lipid bounded structure.
These findings correlate well within vitro biological experiments on MTX cell susceptibility.
Authors:R. Zelkó, Á. Orbán, J. Nagy, G. Csóka, and I. Rácz
In the course of the formulation of coated dosage forms, the selection of the suitable composition of the coating system is
of great importance in respect of the final dosage form. Since the applied coating systems are multicomponent, the possible
interactions between the components determine the physico-chemical stability of the formulated dosage form, the drug release
process, as well as the formulation parameters. In the present study, the influence of the applied plasticizer, dibutyl sebacate
on the enthalpy relaxation of casted Eudragit L 30D films was determined as a function of the plasticizer concentration. The
enthalpy relaxation was recorded by DSC during the applied isothermal recovery process of Eudragit films. The obtained results
indicate that enthalpy relaxation can be measured by DSC at 20 mass/mass% dibutyl sebacate concentration, which refers to
the increased molecular mobility consequently to the effect of the interaction between the polymer and plasticizer.
Authors:H. Razafindralambo, S. Dufour, M. Paquot, and M. Deleu
Isothermal titration calorimetry was applied for studying the binding interactions of cyclic and linear surfactins with different
ionic charge (z= −2 and −3) and lipid chain length (n=14 and 18) to 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidyl-choline (POPC) vesicles in 10mMTris buffer at pH8.5with 150mMNaCl at 25°C. Surfactin analogues interacted
spontaneously (ΔGDw→b < 0) with POPC vesicles. The binding reactions were endothermic (ΔHDw→b > 0) and entropy-driven process (ΔSDw→b > 0). Moreover, significant differences in the binding constant values (K) ranging from 6.6·103 to 9.6·104 M−1 show that cyclic structure and the increase of lipid chain length are favourable on the surfactin binding affinity to POPC
vesicles, whereas the rise of the number of negative charges has an opposite effect.
To clarify the mechanism of the hemolytic activity of 4-META− (4-methacryloyloxyethyl trimellitate anhydride), an evaluation
of the interaction of 4-META and its related compounds (4-MET; phthalic anhydride, PAN; and phthalic acid, PA) with DPPC liposomes
using a DSC and NMR spectroscopy is presented.
Changes in NMR chemical shifts, phase transition temperatures and broadening of the main transition induced by 4-META and
PAN were greater than those induced by 4-MET and PA. The order of decreasing interactions is as follows: 4-META>PAN>4-MET>PA.
Ionized compounds such as 4-MET and PA did not interact with erythrocyte membranes.
The present investigation was carried out to screen compatibility of some diluents with pefloxacin mesilate using differential
scanning calorimetry (DSC), isothermal stability studies, along with stability studies in liquid state and to assign relative
ranking to diluents. Compatibility was predicted with MCC101, MCC102, DCP anhydrous, Emcompress, while melting endotherm of
drug was lost in admixtures of dextrose anhydrous, Pearlitol, Lactopress spray dried, Lactochem fine powder and Lycatab indicating
possibility of interaction. Enthalpy changes were used for relative ranking of diluents.
The theory of âeœcodon-amino acid coevolutionâe? was first proposed by Woese in 1967. It suggests that there is a stereochemical matching - that is, affinity - between amino acids and certain of the base triplet sequences that code for those amino acids. We have constructed a Common Periodic Table of Codons and Amino Acids, where the Nucleic Acid Table showed perfect axial symmetry for codons and the corresponding Amino Acid Table also displayedperiodicity regarding the biochemical properties (charge and hydrophobicity) of the 20 amino acids and the position of the stop signals. The Table indicates that the middle (2 nd) amino acid in the codon has a prominent role in determining some of the structural features of the amino acids. The possibility that physical contact between codons and amino acids might exist was tested on restriction enzymes. Many recognition site-like sequences were found in the coding sequences of these enzymes and as many as 73 examples of codon-amino acid co-location were observed in the 7 known 3D structures (December 2003) of endonuclease-nucleic acid complexes. These results indicate that the smallest possible units of specific nucleic acid-protein interaction are indeed the stereochemically compatible codons and amino acids.
Varga, K., Bányai, E. I. , & Gősi-Greguss, A. Cs. (1994). Parallel application of the experiential analysis technique with subject and hypnotist: A new possibility for measuring interactional synchrony. International Journal of Clinical and