Biomedical subjects
Publications and source records attributed to B Perić.
The molecule of benzene-1,4-dicarboxamidine or benzdiamidine, C(8)H(10)N(4), reveals C(i) symmetry. Hydrogen bonds utilize the amino groups as double donors, whereas the imino groups act as double acceptors. The network formed is similar to that observed in the crystal packing of terephthalamide.
Bis(LeuOH) (1a), bis-(ValOH) (2a) and bis(PhgOH) (5a) (Phg denotes (R)-phenylglycine) oxalyl amides are efficient low molecular weight organic gelators of various organic solvents and their mixtures as well as water, water/DMSO, and water/DMF mixtures. The organisational motifs in aqueous gels are dominated primarily by lipophilic interactions while those in organic solvents are formed by intermolecular hydrogen bonding. Most of the gels are thermoreversible and stable for many months. However, 2a forms unstable gels with organic solvents which upon ageing transform into variety of crystalline shapes. For some 1a/alcohol gels, a linear correlation between alcohol dielectric constants (epsilon) and gel melting temperatures (Tg) was found. The 1H NMR and FTIR spectroscopic investigations of selected gels reveal the existence of temperature dependent network assembly/dissolution equilibrium. In the 1H NMR spectra of gels only the molecules dissolved in entrapped solvent could be observed. By using an internal standard, the concentration of dissolved gelator molecules could be determined. In FTIR spectra, the bands corresponding to network assembled and dissolved gelator molecules are simultaneously present. This enabled determination of the Kgel values by using both methods. From the plots of InKgel versus 1/T, the deltaHgel values of selected gels have been determined (-deltaHgel in 10-36 kJ mol(-1) range) and found to be strongly solvent dependent. The deltaHgel values determined by 1H NMR and FTIR spectroscopy are in excellent agreement. Crystal structures of 2a and rac-5a show the presence of organisational motifs and intermolecular interactions in agreement with those in gel fibres elucidated by spectroscopic methods.
In the title compound, C20H22N4O4*C2H6OS, two distinct hydrogen-bond systems connect oxalamide groups in one pattern and primary amide groups in the other to form a two-dimensional network perpendicular to the c axis. These hydrophilic layers are joined to the three-dimensional structure through C--H...pi interactions. The hydrogen-bonded waved layers shape holes which are occupied by disordered dimethyl sulfoxide solvent molecules.
The title compound, 2,2'-(oxalyldiimino)bis(3-methylbutanoic acid), C12H20N2O6, possesses a centre of symmetry. In the crystal, molecules are connected by hydrogen bonds between oxamide and carboxyl groups, similar to the pattern of the monoclinic forms of HO-Gly-CO-CO-Gly-OH and HO-Aib-CO-CO-Aib-OH (Gly is glycine and Aib is 2-aminoisobutyric acid). The characteristic torsion angles in the title compound are close to those in peptide alpha-helices.
The purpose of this study was to identify histologic differences in epithelial linings between follicular and radicular cysts in relation of their development. Linings and surrounding tissues of 25 radicular and 20 follicular cysts from archival paraffin embedded tissues were obtained and stained with haematoxylin and eosin. Radicular cysts showed orthokeratotic 9-14 cell-layer-thick non-keratinized squamous epithelium and unspecific chronic inflammatory reaction in connective tissue. Follicular cysts showed 2-4 cell-layer-thick of non-keratinized stratified squamous or flattened-low cuboidal epithelium and connective tissue capsule free from inflammatory cell infiltration.
STUDY DESIGN/MATERIALS AND METHODS: This in vitro study was performed upon 50 extracted human molars that provided the occlusal surfaces for standard class I preparations. The cavity floor of the 20 specimens was covered with zinc phosphate cement and the teeth were sectioned transversally at or below the cementoenamel junction. In some specimens pulp tissue was removed from the pulp chamber. The cavities of all specimens were filled with composite resin, and the resin was cured with an argon laser. RESULTS: A statistically significant difference in the rise in temperature was obtained only in the temperature of dentin roof of the pulp chamber between the specimens with (2.2 degrees C) and without (3.1 degrees C) cement base (P < .05). There was no significant difference in the temperature of the pulp tissue between specimens with (2.7 degrees C) and without (2.2 degrees C) base cement. The peak temperature of the composite surface was 13.8 degrees C. CONCLUSION: These data indicate that argon laser curing may be a method of choice for polymerization of the composite resin.
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