Aggregation and Crosslinking of Poly(N,N‐dimethylacrylamide)‐b‐pullulan Double Hydrophilic Block Copolymers

The self‐assembly of polymers is a major topic in current polymer chemistry. In here, the self‐assembly of a pullulan based double hydrophilic block copolymer, namely pullulan‐b‐poly(N,N‐dimethylacrylamide)‐co‐poly(diacetone acrylamide) (Pull‐b‐(PDMA‐co‐PDAAM)) is described. The hydrophilic block copolymer induces phase separation at high concentration in aqueous solution. Additionally, the block copolymer displays aggregates at lower concentration, which show a size dependence on concentration. In order to stabilize the aggregates, crosslinking via oxime formation is described, which enables preservation of aggregates at high dilution, in dialysis and in organic solvents. With adequate stability by crosslinking, double hydrophilic block copolymer (DHBC) aggregates open pathways for potential biomedical applications in the future.     

Validation of an Image Analysis Method for Evaluating the Chemical Resistance of Glass Fibers to Alkaline Environments

This article is focused on the comparison of the reliability of the results obtained by image analysis (newly proposed evaluation method) with well-known methods of evaluation of long-term corrosion resistance of glass fibers in an alkaline environment (pH > 12). The developed method is based on the analysis of scanning electron microscopy images (diameter and structures on the fiber surface). An experiment (52 weeks) was performed to evaluate two types of glass fibers: anticorrosive glass fibers (ARGFs) and E-glass fibers (EGFs). Three media were used to treat the fibers (23 ± 2 °C): H₂O, Ca(OH)₂, and K₂SiO₃. The ARGFs’ tensile strength did not reduce; a decrease by 68% was observed for EGFs in H₂O. Tensile strength decreased by 32% and 85–95% in K₂SiO₃; by 50% and 64% in Ca(OH)₂ for the ARGF and EGF, respectively. Statistical analysis was performed to validate the reliability and plausibility of the developed method. ARGFs and EGFs did not show any relationship between the fiber diameter and weight in H₂O; however, the linear trends may predict this relationship in Ca(OH)₂ and K₂SiO₃. For the ARGF and EGF, the cubic trend was suitable for predicting the change in fiber weight and diameter over time in Ca(OH)₂ and K₂SiO₃.     

Interaction of N-tert-butylaziridine with π-electron acceptors, 2. Polymerization initiated by tetracyanoethylene

The interaction of N-tert-butylaziridine (TBA) with the strong π-electron acceptor tetracyanoethylene (TCNE) was investigated, which results in ring-opening polymerization of the aziridine. Charge-transfer complex formation between TBA and TCNE was proved by means of UV/VIS spectroscopy and is assumed to be the first stage of the initiation. There is evidence that only linear TBA homopolymers are formed and TCNE is not covalently bound in the polymer chains as comonomer. The acceptor is present in the final products as a stable complex with the nitrogen atoms along the polyaziridine chains.     

Effect of immobilization, cold and cold-restraint stress on liver monooxygenase activity and lipid peroxidation of influenza virus-infected mice

The present study provides a direct experimental evidence that the combination of influenza A/Aichi/2/68 (H3N2) infection with different models of "oxidative stress", such as immobilization, cold and cold-restraint, is associated with graduated oxidative disturbances in the liver of mice, despite the absence of virus and inflammation in this tissue. It was found that experimental influenza virus infection is accompanied with a significant increase of lipid peroxidation products, a decrease of natural antioxidants (vitamin E, glutathione) and cytochrome P-450, an inhibition of cytochrome c reductase and liver monooxygenases (analgin- N-demethylase and amidopyrine- N-demethylase). Immobilization and cold stress, applied separately or in combination (cold-restraint), did not influence significantly any of the analysed parameters compared to those of the control group of non-infected mice. Preliminary exposure of mice to immobilization or cold stress and subsequent inoculation of influenza virus resulted in a significant increase of lipid peroxidation products and a significant decrease of vitamin E and reduced glutathione, compared with levels in control (non-infected) animals. Compared to influenza virus-infected and non-stressed animals, the changes in all these parameters were negligible. Immobilization or cold stress, applied in combination with influenza virus infection, partially prevented the suppressive effect of influenza virus on cytochrome P-450 and liver monooxygenases. A tendency towards normalization of these parameters to the control levels was observed. However, after application of cold-restraint plus influenza virus infection, the level of cytochrome P-450 and activity of cytochrome c reductase stayed markedly lower than in infected and non-stressed animals. The activities of liver monooxygenases were slightly increased compared with those of infected and non-stressed animals, but stayed relatively low compared to control (non-infected) mice. Combination of cold-restraint and influenza virus infection resulted in a greater synergistic increase of lipid peroxidation products and a greater synergistic decrease of vitamin E and reduced glutathione compared to controls, as well as to influenza virus-infected and non-stressed animals.     

Synthesis,physicochemical investigation and cytotoxic activity of new Pt(II) complexes with hydantoin ligands

The interaction of cis-dichlorodiaminplatinum(II) (cis-DDP) with 2,4-imidazolidenedione-5-methyl-5-phenyl was studied. The method of preparation of the new Pt(II) complex consisted in precipitation of chloride ions from cis-DDP via a diaqua complex and reaction with the ligand in water-organic media. On the basis of IR spectra, (1)H- and (13)C-NMR analysis the coordination mode of the ligand and most fitting structures of two isomeric complexes were proposed. The pharmacological investigations revealed that the new Pt(II) complex with 5-methyl-5-phenylhydantoin (PtMPH) as well as the previously described Pt(II) complexes with cyclopentanespiro-5'-hydantoin and cyclohexanespiro-5'-hydantoin (PtCHH) exerted concentration-dependent cytotoxic effect in a panel of human tumor cell lines. On the basis of the IC(50) values obtained PtMPH proved to be the most active cytotoxic agent. The other investigated complexes were less active, and among them PtCHH was the least potent antineoplastic agent. The pharmacodynamic investigation of PtMPH showed that this compound induces programmed cell death (apoptosis), as evidenced by the detection of oligonucleosomal DNA fragmentation in HL-60 cells after treatment with PtMPH.     

Uvulopalatopharyngoplasty for sleep apnea in mentally retarded obese 14-year-old: an anaesthetic challenge

Anaesthetic management of patients with obstructive sleep apnea for upper airway surgery has always been a challenging task. We report our anaesthetic approach for a young, mentally retarded obese patient with documented obstructive sleep apnea undergoing uvulopalatopharyngoplasty. The therapeutic intervention before, during and after operation is discussed.     

A case of combined multiple leiomyomas of the skin and psoriasis

A 28-year-old patient is described, suffering from disseminated psoriasis and multiple leiomyomas of the skin. This case is of particular interest because of a rare combination of these two conditions. Leiomyomas in this case were effectively treated by laser exposure.     

Pringle-Bourneville disease

A patient suffering from this disease is described, who developed it at the age of 30. Besides eruptions, the condition is characterized by central nervous system shifts. A promising effect of laser therapy is of interest in this case.