Comparative studies on short‐chain and long‐chain crosslinking in polyurethane networks

Isocyanate terminated prepolymers were synthesised using poly(tetramethylene oxide) glycol of molecular weight 1 000 (PTMG₁₀₀₀) and poly(propylene oxide) glycol of molecular weight 1 000 (PPG₁₀₀₀) with tolylene‐2,4‐diisocyanate (TDI). The prepolymers were chain extended with N,N‐bis(2‐hydroxyethyl)isonicotinamide to form polyurethanes containing pyridine moieties. These polyurethanes were converted to cationomers by crosslinking with (a) 1,4‐dibromobutane to form short‐chain crosslinked polymers (SCCPs) and (b) bromine‐terminated prepolymers to form long‐chain crosslinked polymers (LCCPs). The cationomers were characterised by Fourier transform infrared spectroscopy, thermal and mechanical analysis. FTIR spectral results of SCCPs and LCCPs confirmed the quaternisation of heterocyclic nitrogen leading to crosslinking. Dynamic mechanical analysis showed better damping properties for LCCPs than SCCPs. The stress‐strain measurements showed higher elongation and lower tensile strength for LCCPs.     

Urothelial carcinoma arising from the transplanted kidney: A single‐center experience and literature review

Urothelial carcinoma (UC) is a malignancy predominantly arising in the bladder. Upper tract UC (UUC) is uncommon, accounting only for 5‐10% of the cases. High incidence of neoplasms is associated with immunosuppressive therapy; thus, UCs of the transplanted grafts often lead to a more aggressive treatment, in order to withdraw completely the immunosuppression. It significantly affects the patient quality of life, meaning return to dialysis, along with the worse life expectancy. We present our single‐institution experience of this rare malignancy in two mid‐age kidney transplant recipients, with UCs successfully treated with radical nephroureterectomy: G3 pT3 N0 + G3 pT1 N0 in the first patient and G3 pT2 N0 in the second one. We also review the previous literature focusing on stage of presentation and treatment for the affected kidney transplant patients.     

Neutrophil elastase, an innate immunity effector molecule, represses flagellin transcription in Pseudomonas aeruginosa

Recognition of pathogen-associated molecular patterns (PAMPs) by pattern recognition receptors triggers an innate immune response to colonizing or invading bacteria. Conversely, many bacteria have evolved mechanisms to dampen this response by downregulating the synthesis of such PAMPs. We have previously demonstrated that Pseudomonas aeruginosa growing in mucopurulent human respiratory mucus from cystic fibrosis patients represses the expression of its flagellin, a potent stimulant of the innate immune response. Here we demonstrate that this phenomenon occurs in response to the presence of neutrophil elastase in such mucus. Nonpurulent mucus from animals had no such repressive effect. Furthermore, lysed neutrophils from human blood reproduced the flagellin-repressive effect ex mucus and, significantly, had no effect on the viability of this organism. Neutrophil elastase, a component of the innate host defense system, has been described to be bactericidal for gram-negative bacteria and to degrade bacterial virulence factors. Thus, the resistance of P. aeruginosa to the bactericidal effect of neutrophil elastase, as well as this organism's ability to sense this enzyme's presence and downregulate the synthesis of a PAMP, may be the key factors in allowing P. aeruginosa to colonize the lungs. These findings demonstrate the dynamic nature of this bacterium's response to host defenses that ensures its success as a colonizer and also highlights the dual nature of defense molecules that confer advantages and disadvantages to both hosts and pathogens.     

Production and characterization of guinea pig recombinant gamma interferon and its effect on macrophage activation

Gamma interferon (IFN-gamma) plays a critical role in the protective immune responses against mycobacteria. We previously cloned a cDNA coding for guinea pig IFN-gamma (gpIFN-gamma) and reported that BCG vaccination induced a significant increase in the IFN-gamma mRNA expression in guinea pig cells in response to living mycobacteria and that the virulent H37Rv strain of Mycobacterium tuberculosis stimulated less IFN-gamma mRNA than did the attenuated H37Ra strain. In this study, we successfully expressed and characterized recombinant gpIFN-gamma with a histidine tag at the N terminus (His-tagged rgpIFN-gamma) in Escherichia coli. rgpIFN-gamma was identified as an 18-kDa band in the insoluble fraction; therefore, the protein was purified under denaturing conditions and renatured. N-terminal amino acid sequencing of the recombinant protein yielded the sequence corresponding to the N terminus of His-tagged gpIFN-gamma. The recombinant protein upregulated major histocompatibility complex class II expression in peritoneal macrophages. The antiviral activity of rgpIFN-gamma was demonstrated with a guinea pig fibroblast cell line (104C1) infected with encephalomyocarditis virus. Interestingly, peritoneal macrophages treated with rgpIFN-gamma did not produce any nitric oxide but did produce hydrogen peroxide and suppressed the intracellular growth of mycobacteria. Furthermore, rgpIFN-gamma induced morphological alterations in cultured macrophages. Thus, biologically active rgpIFN-gamma has been successfully produced and characterized in our laboratory. The study of rgpIFN-gamma will further increase our understanding of the cellular and molecular responses induced by BCG vaccination in the guinea pig model of pulmonary tuberculosis.     

Idiopathic gingival fibromatosis. A case report.

Gingival fibromatosis is a progressive gingival enlargement caused by an over growth of the collagenous element of the gingival fibrous connective tissue. Pharmacologically induced, hereditary (familial) and idiopathic forms of gingival fibromatosis are recognized. This paper reports a case of idiopathic gingival fibromatosis in a 13 year old boy involving the right maxillary and mandibular arches who had also been treated 3 years back for a gingival enlargement involving the left maxillary and mandibular arches. The enlargement was quite sever and caused significant esthetic and functional problems on both occasions.     

Exostoses of the paranasal sinuses

While bony exostoses of the external auditory canal have long been recognized as a complication of cold-water swimming, bony exostoses of the paranasal sinuses have not been previously reported. We present an unusual case of multiple exostoses of the paranasal sinuses, which began coincident with nasal irrigation with cold gentamicin solution. The patient had had prior endoscopic sinus surgery. Topical antibiotic gentamicin irrigation lessened recurrence of bacterial sinus episodes. He admitted to using the irrigation directly from the refrigerator daily for two years. A biopsy was consistent with exostosis. Patients should be counseled to avoid irrigating their paranasal sinuses with cold irrigants. Laryngoscope, 2010.     

Effect of cranberry juice concentrate on chemically-induced urinary bladder cancers

The chemopreventive efficacy of cranberry juice concentrate in an experimental model of urinary bladder cancer was evaluated using female Fischer-344 rats. The animals received N-butyl-N-(4-hydroxybutyl)-nitrosamine (OH-BBN) for a period of eight weeks. Cranberry juice concentrate was administered at doses of 1.0 or 0.5 ml/rat/day beginning one week after the final OH-BBN treatment and continuing until the end of the study. The urinary bladders of all the rats were weighed and examined grossly for lesions, and all masses were submitted for pathological evaluation. A dose-dependent preventive effect of cranberry treatment was observed, with a reduced number of urinary bladder cancers (38%) in the 1.0 ml/rat/day group versus the control group. The cranberry extract neither affected body weight gain nor caused other signs of toxicity. For the metabolic studies, serum and urine were collected at 4 and 12 h after the administration of the cranberry juice concentrate and were analyzed by LC-MS/MS. Quercetin and its methylated derivative were detected in the urine samples. However, no quercetin was detected in the serum samples, indicating its poor bioavailability. These data suggest that components of cranberries may be effective in preventing urinary bladder carcinogenesis.