Surface properties and cell response of low metal ion release Ti-6Al-7Nb alloy after multi-step chemical and thermal treatments

Ti-6Al-7Nb samples treated by innovative multi-step chemical and thermal processes were characterized in order to evaluate their surface properties and cell interaction. The main object was to asses if the treatments were effective in order to obtain a surface presenting at the same time bone-like apatite induction ability, low metal ion release, good cell response and high protein binding. The morphology, crystallographic structure, porosity and wettability of the treated materials were investigated, as well as their interaction with simulated body fluid during soaking for different times. Cytotoxicity, protein adsorption tests and in vitro fibroblast and osteoblast-like cell cultures were also performed.     

Synthese und charakterisierung von linearem poly(iminoethylen)

Linear poly(iminoethylene) was synthetised by cationic polymerization of 2-methyl-2-oxazoline using BF₃? O(C₂H₅)₂, SnCl₄, and CH₃COBF₄ as initiators and in the presence or absence of CH₃CN. The resulting product, poly(N-acetyliminoethylene), was then hydrolysed in basic medium. The resulting poly(iminoethylene) was identified and characterized by ¹H NMR, ¹³C NMR, X-ray diffraction, and differential scanning calorimetry (DSC). The synthetised polymer will be used as a polymeric support in ionic-exchange resins as well as in macromolecular pesticides.     

Partial protective effect of CCR5-Delta 32 heterozygosity in a cohort of heterosexual Italian HIV-1 exposed uninfected individuals

Despite multiple sexual exposure to HIV-1 virus, some individuals remain HIV-1 seronegative (exposed seronegative, ESN). The mechanisms underlying this resistance remain still unclear, although a multifactorial pathogenesis can be hypothesised. Although several genetic factors have been related to HIV-1 resistance, the homozigosity for a mutation in CCR5 gene (the 32 bp deletion, i.e. CCR5-Delta32 allele) is presently considered the most relevant one. In the present study we analysed the genotype at CCR5 locus of 30 Italian ESN individuals (case group) who referred multiple unprotected heterosexual intercourse with HIV-1 seropositive partner(s), for at least two years. One hundred and twenty HIV-1 infected patients and 120 individuals representative of the general population were included as control groups. Twenty percent of ESN individuals had heterozygous CCR5-Delta 32 genotype, compared to 7.5% of HIV-1 seropositive and 10% of individuals from the general population, respectively. None of the analysed individuals had CCR5-Delta 32 homozygous genotype. Sequence analysis of the entire open reading frame of CCR5 was performed in all ESN subjects and no polymorphisms or mutations were identified. Moreover, we determined the distribution of C77G variant in CD45 gene, which has been previously related to HIV-1 infection susceptibility. The frequency of the C77G variant showed no significant difference between ESN subjects and the two control groups.     

F2-isoprostanes stimulate collagen synthesis in activated hepatic stellate cells: a link with liver fibrosis?

Carbon tetrachloride (CCl4)-induced hepatic fibrosis has been considered to be linked to oxidative stress and mediated by aldehydic lipid peroxidation products. In the present study, we investigated whether collagen synthesis is induced by F2-isoprostanes, the most proximal products of lipid peroxidation and known mediators of important biological effects. By contrast with aldehydes, F2-isoprostanes act through receptors able to elicit definite signal transduction pathways. In a rat model of CCl4-induced hepatic fibrosis, plasma F2-isoprostanes were markedly elevated for the entire experimental period; hepatic collagen content also increased. When hepatic stellate cells (HSCs) from normal liver were cultured with F2-isoprostanes in the concentration range found in the in vivo studies (10(-9)-10(-8) M), a striking increase in DNA synthesis (reversed by the thromboxane A2 antagonist SQ 29 548), in cell proliferation and in collagen synthesis was observed. Total collagen content was similarly increased. Moreover, F2-isoprostanes markedly increased the production of transforming growth factor-beta1 by U937 cells, considered a model of liver macrophages. The data provide evidence for the possibility that F2-isoprostanes generated by lipid peroxidation in hepatocytes mediate HSC proliferation and collagen production seen in hepatic fibrosis.     

CD34+ Cord Blood Cell-Transplanted Rag2−/− γc−/− Mice as a Model for Epstein-Barr Virus Infection

Recent studies suggest that Epstein-Barr virus (EBV) can infect naïve B cells, driving them to differentiate into resting memory B cells via the germinal center reaction. This hypothesis has been inferred from parallels with the biology of normal B cells but has never been proven experimentally. Rag2^−/− γ_c^−/− mice that were transplanted with human CD34⁺ cord blood cells as newborns were recently shown to develop human B, T, and dendritic cells, constituting lymphoid organs in situ. Here we used this model to better define the strategy of EBV infection of human B cells in vivo and to compare this model system with different conditions of EBV infection in humans. Our results support the model of EBV persistence in vivo in cases that were characterized by follicular hyperplasia and a relatively normal CD4⁺ and CD8⁺ T-cell distribution. Intriguingly, in cases that were characterized by nodular and diffuse proliferation with a preponderance of CD8⁺ T cells, similar to infectious mononucleosis, EBV still infects naïve B cells but also induces clonal expansion and ongoing somatic mutations without germinal center reactions. Our results reveal different strategies of EBV infection in B cells that possibly result from variations in the host immune response. Future experiments might allow understanding of the mechanisms responsible for persistent EBV infection and provide targets for more highly tailored therapeutic interventions.     

Etherification of poly(oxymethylene)-diol [α-hydro-ω-hydroxypoly(oxymethylene)] with orthoesters in the presence of Lewis acids

Attempts were made to elucidate experimentally the behaviour of poly(oxymethylene)-diol [α-hydro-ω-hydroxypoly(oxymethylene)] in the etherification reaction in order to explain the decrease of the polymer molecular weight compared with that of the starting product and in order to determine the type of terminal groups and how the thermal resistance and alkali stability can be affected. In fact one finds that, in addition to the wanted terminal ether groups, formyl and orthoformyl (dialkoxymethyl) groups are formed having a different chemical resistance in comparison to that of the pure ethers, particularly in basic media.     

Hypoglycaemic syndromes and antibodies to pancreatic islet cells.

The sera of ten patients with unexplained hypoglycaemia were examined for antibodies to pancreatic islets. Antibodies to pancreatic A, B and D cells (ICAb) were detected in one patient with an associated gastrointestinal tumour.     

Expression of Intercellular Adhesion Molecule-1 (ICAM-1) on Cultured Human Endometrial Stromal Cells and Its Role in the Interaction With Natural Killers

PROBLEM: Recent evidence emphasizes the role of natural killer cells (NKs) as potential effectors of peritoneal immune surveillance directed against the outgrowth of endometrial cells, refluxed with menstrual debris, in ectopic sites. This NK-mediated cytotoxicity toward autologous endometrial antigens seems to be significantly decreased in endometriosis patients. METHOD: We set up experiments to clarify which molecules are involved in NK-endome-trial cell interaction. In particular, we evaluated the surface expression and functional activity of intercellular adhesion molecule-1 (ICAM-1), a cell surface glycoprotein that has been identified as one of the ligands for lymphocyte function-associated antigen-1 (LFA-1), present on almost all leucocyte cell types. Immunofluorescence flow cytometry was used to assess ICAM-1 expression on resting and IL 1β-activated endometrial stromal cells in culture. Dermal fibroblasts were used as control cells. Cytotoxicity and binding assays by ⁵¹Cr release in presence and absence of a specific monoclonal antibody (mAb) against ICAM-1 were then performed in order to determine the effect of this molecule on NK-mediated cytotoxic and binding activity toward endometrial stromal cells. RESULTS: The results of this study indicated that ICAM-1 expression on endometrial stromal cells seems to be constitutively higher than on dermal fibroblasts and can be up-regulated upon exposure to IL 1β. Furthermore, a mAb against ICAM-1 strongly inhibits the binding but not the cytotoxicity of NKs toward endometrial cells. No difference in the expression of this molecule was observed throughout the cycle. CONCLUSIONS: The presence of ICAM-1 on human endometrium might relate to the action of the immunocompetent cells in human specific reproductive events.