Polyphenols from Grape Pomace: Functionalization of Chitosan-Coated Hydroxyapatite for Modulated Swelling and Release of Polyphenols.

Chitosan is known for its specific antibacterial mechanism and biodegradability, while polyphenols are known for their antioxidant and anti-inflammatory properties: coupling these properties on a surface for bone contact, such as hydroxyapatite, is of great interest. The system developed here allows the combination of hydroxyapatite, chitosan, and polyphenol properties in the same multifunctional biomaterial in order to modulate the host response after implantation. Crosslinked chitosan is used in this research to create a stable coating on hydroxyapatite, and then it is functionalized for a smart release of the polyphenols. The release is higher in inflammatory conditions and lower in physiological conditions. The properties of the coated and functionalized samples are characterized on the as-prepared samples and after the samples are immersed (for 24 h) in solutions, which simulate the inflammatory and physiological conditions. Characterization is performed in order to confirm the presence of polyphenols grafted within the chitosan coating, the stability of grafting as a function of pH, the morphology of the coating and distribution of polyphenols on the surface, and the redox reactivity and radical scavenging activity of the functionalized coating. All the results are in line with previous results, which show a successful coating with chitosan and functionalization with polyphenols. Moreover, the polyphenols have a different release kinetics that is faster in a simulated inflammatory environment compared to that in the physiological environment. Even after the release tests, a fraction of polyphenols are still bound on the surface, maintaining the antioxidant and radical scavenging activity for a longer time. An electrostatic bond occurs between the negative-charged polar groups of polyphenols (carboxyls and/or phenols) and the positive amide groups of the chitosan coating, and the substitution of the crosslinker by the polyphenols occurs during the functionalization process.

Pentoxifylline augments but does not antagonize TNF alpha-mediated neuroblastoma cell differentiation: modulation of calcium mobilization but not cAMP.

We described here that pentoxifylline (PTX), which is well known to counteract tumor necrosis factor alpha (TNF alpha)-mediated inflammatory responses, augmented TNF alpha-induced neuroblastoma cell differentiation in conjunction with growth inhibition and cell-cycle arrest in G1 phase. PTX also enhanced TNF alpha-induced down-regulation of acetylcholine-mediated [Ca2+]i mobilization in neuroblastoma cells. Furthermore, we found that addition of cAMP failed to induce neuroblastoma cell differentiation, whereas blockade of [Ca2+]i mobilization by 8-(N,N-diethyl-amino)octyl-3,4,5-trimethoxybenzoate HCl (TMB-8, 10 microM) did induce neuroblastoma cell differentiation. Taken together, these results indicated that PTX possessed a novel signal transduction, down-regulation of [Ca2+]i mobilization, to augment but not counteract TNF alpha-mediated functions.

Toxoplasmosis in Singapore.

The present paper reports research done in the following areas in the Parasitology Unit of the Department of Microbiology, National University of Singapore: determination of anti-Toxoplasma gondii antibodies in different IgG subclasses; immunoblot analysis of the antibody response to T. gondii and identification of key reactive epitopes; production and characterization of monoclonal antibodies to T. gondii; and the development of an IgM capture ELISA. IgG1 is the dominant subclass involved in the humoral response to T. gondii. IgG3 and IgG4 may be produced at low but significant levels. IgG2 production was not apparent. Immunoblot analysis of the positive sera revealed that the major antigens recognized by IgG and IgM antibodies were of MW 22, 35 and 67 kDa. Many of the bands observed in blots with positive sera were also present in blots with negative sera. The 22 kDa band was seen in majority of positive sera and was generally absent in negative sera. Anti-Toxoplasma sera also revealed IgA antibodies. Immunoblot analysis of the antigen revealed a 14 kDa band that reacted with all IgA positive sera. From a panel of monoclonals produced against T. gondii, one monoclonal, 5F3 (A) was selected for development of a monoclonal based IgM capture ELISA for detection of antibodies to 22 kDa and 41 kDa epitopes of T. gondii.

Ectopic ACTH syndrome due to clear cell sarcoma of the kidney.

The 7-year-old girl presenting with cushingoid appearance and gross hematuria was found to have a right renal tumor. Preoperative hormonal assay revealed an extremely high plasma ACTH level and elevated plasma cortisol levels. Right radical nephrectomy was performed, and pathology proved the tumor to be a clear cell sarcoma, a sarcomatous variant of Wilms' tumor, of the kidney. Postoperative plasma ACTH level declined dramatically and cortisol levels returned to normal, too. She received chemotherapy and radiotherapy then and gradually lost her cushingoid appearance. This is the first reported case of clear cell sarcoma of the kidney with ectopic ACTH syndrome.

Determination of antiamoebic IgG, IgM, IgA and IgG subclasses in sera from patients with amoebiasis by enzyme-linked immunosorbent assay.

The HK-9 strain of Entamoeba histolytica was cultured axenically. A crude extract of the trophozoites was used as antigen in the enzyme-linked immunosorbent assay (ELISA) for the determination of antiamoebic IgG, IgM, IgA and IgG subclasses in sera of patients with E. histolytica infection. Sera from amoebiasis patients had significantly higher mean ELISA values for all classes and subclasses of immunoglobulins examined compared with healthy controls. The ELISA for IgG, IgM and IgA was positive for 76 (97.4%), 34 (43.6%) and 62 (79.5%) respectively of 78 amoebiasis sera. Analysis of IgG subclasses by ELISA showed that 76.7%, 25%, 33.3% and 66.6% of the patients were positive for antiamoebic IgG1, IgG2, IgG3 and IgG4 respectively. IgG1 and IgG4 were the dominant IgG subclasses involved in amoebiasis. The role of antiamoebic antibodies in amoebiasis is discussed.

A comparison of the ELISA with other serological tests in the serodiagnosis of amoebiasis.

The sera of 78 patients with invasive amoebiasis were tested for antiamoebic antibodies by the techniques of enzyme-linked immunosorbent assay (ELISA), indirect haemagglutination (IHA), indirect fluorescent antibody (IFA) and counterimmunoelectrophoresis (CIEP). Results showed that the ELISA compared favourably with IHA and IFA tests in terms of sensitivity and specificity. ELISA, IHA and IFA detected 97.4%, 96.2% and 98.7% of the patients respectively. CIEP was the least sensitive of the 4 serological methods with a sensitivity of 88.5%. The advantages and disadvantages of the 4 serodiagnostic procedures are discussed.