Efficiency of desensitizing materials in xerostomic patients with head and neck cancer: a comparative clinical study.

OBJECTIVES: To assess the clinical effectiveness of four desensitizing materials in patients who are xerostomic due to radiotherapy for head and neck cancer (HNC) in comparison to a healthy group with normal salivation. METHODS AND MATERIALS: The study was conducted as a split-mouth randomized clinical trial. Forty HNC patients (group A) and 46 healthy patients (group B) suffering from dentin hypersensitivity (DH) were included. Salivary flow was determined through a scialometric test. Hypersensitivity was assessed with air stimulus and tactile stimulus. The materials used as desensitizing agents were Vertise Flow, Universal Dentin Sealant, Clearfil Protect Bond, and Flor-Opal Varnish. The response was recorded before application of the materials, immediately after, and at 1 week, 4 weeks, and 12 weeks. RESULTS: Salivary flow rates in groups A/B were 0.15/0.53 mL/min (unstimulated) and 0.54/1.27 mL/min (stimulated), respectively. In group A, 100 hypersensitive teeth were included. Application of the desensitizing agents significantly decreased the hypersensitivity immediately and throughout the 4-week follow-up (p < 0.001). However, after the 12-week timepoint, a loss of efficacy was detected in all agents (p = 0.131). In group B, 116 hypersensitive teeth were included. The materials performed a more stable action, although a loss of effectiveness was detected at 12-week control (p = 0.297). CONCLUSION: The efficiency of the desensitizing agents after the first application was similar in both groups. In the radiated group, this effect lasted for shorter periods than in healthy controls. CLINICAL RELEVANCE: HNC patients with hyposalivation may be a new risk group for DH.

Dental pulp regeneration via cell homing.

The typical treatment for irreversibly inflamed/necrotic pulp tissue is root canal treatment. As an alternative approach, regenerative endodontics aims to regenerate dental pulp-like tissues using two possible strategies: cell transplantation and cell homing. The former requires exogenously transplanted stem cells, complex procedures and high costs; the latter employs the host's endogenous cells to achieve tissue repair/regeneration, which is more clinically translatable. This systematic review examines cell homing for dental pulp regeneration, selecting articles on in vitro experiments, in vivo ectopic transplantation models and in situ pulp revascularization. MEDLINE/PubMed and Scopus databases were electronically searched for articles without limits in publication date. Two reviewers independently screened and included papers according to the predefined selection criteria. The electronic searches identified 46 studies. After title, abstract and full-text examination, 10 articles met the inclusion criteria. In vitro data highlighted that multiple cytokines have the capacity to induce migration, proliferation and differentiation of dental pulp stem/progenitor cells. The majority of the in vivo studies obtained regenerated connective pulp-like tissues with neovascularization. In some cases, the samples showed new innervation and new dentine deposition. The in situ pulp revascularization regenerated intracanal pulp-like tissues with neovascularization, innervation and dentine formation. Cell homing strategies for pulp regeneration need further understanding and improvement if they are to become a reliable and effective approach in endodontics. Nevertheless, cell homing currently represents the most clinically viable pathway for dental pulp regeneration.

Periodontal status in an Italian young adult population. Prevalence and relationship with periodontopathic bacteria.

To determine the prevalence of periodontitis in an Italian young adult population and the relationship with Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis and Prevotella intermedia in subgingival plaque. A full-mouth periodontal and oral examination was performed in 70 subjects. Dental and behaviour habits were assessed with a standardised questionnaire. Subgingival plaque samples were collected from the deepest pocket of the first molars in each quadrant with a sterile curette. A. actinomycetemcomitans, P. gingivalis and P. intermedia were detected using a multiplex polymerase chain reaction. At subject level, the prevalence of bleeding on probing, calculus, normal pocket depth (PD), PD > 5mm and bacterial positivity were 44.8%, 43.3%, 22.9%, 11.4% and 95.7%, respectively. At quadrant level bacterial prevalence was 79.4%; P. intermedia was the most common bacteria (79.0%); A. actinomycetemcomitans had a prevalence of 40.8%. A significant linear trend across categories of gingival conditions (healthy, bleeding on probing, calculus presence) was detected for P. intermedia (p = 0.0038) and A. actinomycetemcomitans (p = 0.00005) proportions. No significant association was observed between pathogenic bacteria and PD, nor with behavioural attitudes. Gingival conditions are found to be a good predictors (VPP = 85%) for periodontopathic bacteria. For the Italian population, as no data are present, prospective longitudinal studies are needed to examine the relationship between PD and bacteria presence with periodontal disease onset and/or progression.

A repertoire library that allows the selection of synthetic SH2s with altered binding specificities.

Tyrosine phosphorylation is one of the major mechanisms involved in the intracellular propagation of external signals. Strategies aimed at interfering with this process might allow the control of several cellular phenotypes. SH2 domains mediate protein-protein interactions by recognizing phosphotyrosine (pY) residues in the context of specific phosphopeptides. We created an SH2-scaffolded repertoire library by randomly mutagenizing five critical amino acid positions in the specificity-determining region of the PLCgamma C-terminal SH2 domain. Synthetic SH2 domains were selected from the library using biotinylated phosphopeptides derived from a natural PLCgamma-SH2 ligand as well as unrelated SH2 ligands. The isolated SH2s displayed high binding affinity constants for the selecting peptides and were capable of interacting with the corresponding proteins.

A motif within the T cell receptor alpha chain constant region connecting peptide domain controls antigen responsiveness.

Mutant alphabeta TCRs were generated by replacing domains of the alpha and beta chain constant regions with homologous domains from TCR delta and gamma chains, respectively. Chimeric TCRs in which the alpha chain contains TCR delta chain sequences within the connecting peptide domain are unresponsive to alloantigens and superantigens, and have defective interactions with the CD3/zeta complex. Although these antigen-unresponsive TCRs undergo zeta chain phosphorylation upon stimulation with superantigen, they do not generate a full signal capable of producing IL-2. Mutant TCRs acquire signaling activity with a combination of superantigen and calcium ionophore, indicating a defect in calcium-mediated signaling. Finally, a conserved motif, FETDxNLN, present in the alpha chain connecting peptide domain, is disrupted in all signaling-defective TCRs. This conserved alpha chain connecting peptide motif might mediate the transfer of signals from the alphabeta heterodimer to the CD3/zeta complex.

The aminoterminal phosphotyrosine binding domain of Shc associates with ZAP-70 and mediates TCR dependent gene activation.

T-cell antigen receptor stimulation results in recruitment to the zeta chain and phosphorylation both of the syk family protein tyrosine kinase ZAP-70 and of the Shc adaptor protein, which transduces activating signals to Ras. Both ZAP-70 and Ras are required for T-cell activation. We have investigated the functional link between these two molecules in TCR signaling. She was found to associate with ZAP-70 in response to TCR triggering. This association was dependent on the presence of the aminoterminal phosphotyrosine binding (PTB) domain of She. The analysis of She binding to a potential PTB domain binding site on ZAP-70 confirmed the interaction of the She PTB domain with ZAP-70 and identified the ZAP-70 phosphotyrosine residue involved in this interaction. To test the role of the She PTB domain in transducing TCR derived signals we measured the effects of the isolated She PTB domain on the activation of the T-cell specific transcription factor NF-AT. The isolated She PTB domain was designed to compete non productively with endogenous She for binding to up-stream tyrosine phosphorylated proteins and thus interfere with coupling to regulators of Ras activation. A significant inhibition of NF-AT activation by TCR triggering was observed, showing a functional involvement of She in TCR signaling through its PTB domain and suggesting an important role for She association with ZAP-70.

[Activation of the immune system in periapical infection. 1. Lympho-monocytoid and plasma cellular elements of reactive soft tissue cells]. / Attivazione del sistema immunocompetente nella patologia del periapice infetto. Nota 1: elementi cellulari della serie linfomonocitoide, plasmacellulare e propri dei tessuti molli reattivi.

The authors have carried out a study on the immunitary mechanisms which stimulate and avoid eventual alterations of infected periapex. Above all the aim of this first study has been the microscopic and ultrastructural valuation of the cellular components that characterize the process of chronic phlogosis of periradicular tissue, lymphocytes T and B, plasmacells and macrophages, and of those even more typical of the soft reactive tissues, fibroblasts and epithelial cells. It's just the interaction among these immunocompetent cells which determines the structural change of the periapical bone whose most common image of radiotransparence make it possible to diagnose the sufference of the pulpo-periapical system.

Distinct signaling properties identify functionally different CD4 epitopes.

The CD4 coreceptor interacts with non-polymorphic regions of major histocompatibility complex class II molecules on antigen-presenting cells and contributes to T cell activation. We have investigated the effect of CD4 triggering on T cell activating signals in a lymphoma model using monoclonal antibodies (mAb) which recognize different CD4 epitopes. We demonstrate that CD4 triggering delivers signals capable of activating the NF-AT transcription factor which is required for interleukin-2 gene expression. Whereas different anti-CD4 mAb or HIV-1 gp120 could all trigger activation of the protein tyrosine kinases p56lck and p59fyn and phosphorylation of the Shc adaptor protein, which mediates signals to Ras, they differed significantly in their ability to activate NF-AT. Lack of full activation of NF-AT could be correlated to a dramatically reduced capacity to induce calcium flux and could be complemented with a calcium ionophore. The results identify functionally distinct epitopes on the CD4 coreceptor involved in activation of the Ras/protein kinase C and calcium pathways.

Interactions between the tyrosine kinases p56lck, p59fyn and p50csk in CD4 signaling in T cells.

Interaction of the CD4 co-receptor with major histocompatibility complex (MHC) class II molecules during antigen presentation results in enhancement of antigen receptor signaling. The synergism between the two receptors is believed to result from the juxtaposition of the CD4-associated tyrosine kinase p56lck with the cytoplasmic domains of CD3 complex components. Here, we report that cross-linking of CD4 on the surface of Jurkat cells using monoclonal antibodies results in activation of the CD3-associated kinase p59fyn. Co-cross-linking of CD4 and CD3 results in synergistic activation of p59fyn. The p59fyn kinase is also hyperactive in a Jurkat cell line stably transfected with a constitutively active p56lck mutant, indicating that p56lck mediates CD4 activation of p59fyn. In support of this hypothesis, expression of a dominant inhibitory mutant of p59fyn blocks CD4 signals involved in gene activation. In addition, the p59fyn dominant inhibitor mutant blocks gene-activating signals induced by expression of a constitutively active mutant of p56lck. Overexpression of the regulatory kinase p50csk, which attenuates TcR signaling by inactivation of p59fyn, inhibits signaling from the constitutively active form of p56lck. Taken together, these data suggest that CD4/p56lck enhancement of TcR signaling is, at least in part, mediated by activation of p59fyn, and may be regulated by p50csk.

Inhibition of CD4/p56lck signaling by a dominant negative mutant of the Shc adaptor protein.

T-cell antigen receptor stimulation results in phosphorylation of the SH2 containing Shc proteins and recruitment of the Grb2/mSos complex suggesting that Shc proteins are involved in transducing T-cell activating signals to Ras. We have measured the effects of the isolated Shc-SH2 domain and the dominant negative RasN17 protein on activation of the T-cell specific transcription factor NF-AT. The isolated Shc-SH2 domain was designed to compete with endogenous Shc binding to upstream tyrosine phosphorylated proteins and to interfere with coupling to regulators of Ras activation. We have demonstrated that both the Shc-SH2 domain and the RasN17 protein significantly inhibited NF-AT activation by the CD4 coreceptor and the CD4 associated tyrosine kinase p56lck. In contrast, only the RasN17 protein reduced NF-AT activation by the TCR/CD3 complex. Furthermore, tyrosine kinase activity and p56lck protein were found in complexes immunoprecipitated with Shc specific antisera after CD4 triggering but not after CD3 triggering. These results indicate that both CD4 and CD3 signal to Ras and that this signaling is mediated by independent pathways of activation of the Shc adaptor protein.

Cell vacuolization induced by Helicobacter pylori: inhibition by bafilomycins A1, B1, C1 and D.

All available bafilomycins (A1, B1, C1 and D) inhibit and revert macroscopic vacuolization induced by Helicobacter pylori cell-free extracts. Bafilomycin A1 displays the highest activity, followed by bafilomycin B1, C1 and D. The different potency of bafilomycins correlates with their ability to inhibit the vacuolar-type ATPase (V-ATPase) and to dissipate the membrane pH gradient of intracellular acidic organelles. These results suggest that bafilomycins should be considered as possible therapeutic agents in the treatment of gastritis.