Infrared reflection-absorption spectroscopy of thin film structures

Infrared reflection-absorption spectroscopy has been used extensively in the study of adsorbates and thin films on metal surfaces, but little work has been performed on semiconductor and metal oxide surfaces due to the lack of sensitivity of the technique on these surfaces;In this work, IRRAS has been used to investigate the optical properties of thin film structures consisting of an optically thin layer of the nonmetallic component on an optically thick reflecting metal film. The sensitivity of the technique has been investigated by the use of thin polymer films of various thickness spun on thin film structures and compared with the transmission infrared spectra of similar films. The technique showed remarkable sensitivity to the thin films, several orders of magnitude more sensitivity than the corresponding transmission spectra. The technique was applied to the deposition of thin palladium films on silicon and copper surfaces by the decomposition of palladium acetate. Thin films of the acetate reacted much differently under oxidizing and reducing atmospheres and on different substrates, suggesting that substrate interactions play an important role in the decomposition process;Investigations were performed in order to determine the applicability of the technique to the study of thin layers and adsorbed molecules on metal oxide catalyst materials. It was determined that the technique exhibits sufficient sensitivity for the study of reaction and adsorption processes on metal oxide surfaces while avoiding the limitations of low surface area and low infrared transmittance. In addition, structural and compositional changes in the thin films were easily observed. The reactions of thin molybdenum trioxide films were studied in order to investigate the sensitivity of the technique to thin catalyst films. Both structural and compositional changes in thin oxide films were easily observable as a function of the atmosphere and reacting molecules above the film

Poly(alkyl methacrylate) tooth coatings for dental care: evaluation of the demineralisation-protection benefit using a time-resolved in vitro method

An in vitro method for the time-resolved quantification of acid-mediated tooth demineralisation has been developed and evaluated against putative non-permanent protective formulations based on a series of poly(alkyl methacrylate)s. Using a thermostatted carousel, dentally relevant substrates consisting of hydroxyapatite discs or sections of bovine teeth have been exposed to aqueous citric acid under controlled conditions, before and after being treated with the polymeric coatings. The dissolution of phosphate was monitored by the determination of 31P by Inductively Coupled Plasma—Mass Spectrometry and by the spectrophotometric phosphovanadomolybdate method. Dose-response plots constructed for both groups of treated substrates have revealed that the coatings significantly reduce erosion rates but are less effective at inhibiting tooth demineralisation than the standard fluoride treatment. The approach has enabled an evaluation of the erosion-protection efficiency of each coating

Disease-associated Bias in T Helper Type 1 (Th1)/Th2 CD4+ T Cell Responses Against MAGE-6 in HLA-DRB1*0401+ Patients With Renal Cell Carcinoma or Melanoma

T helper type 1 (Th1)-type CD4+ antitumor T cell help appears critical to the induction and maintenance of antitumor cytotoxic T lymphocyte (CTL) responses in vivo. In contrast, Th2- or Th3/Tr-type CD4+ T cell responses may subvert Th1-type cell-mediated immunity, providing a microenvironment conducive to disease progression. We have recently identified helper T cell epitopes derived from the MAGE-6 gene product; a tumor-associated antigen expressed by most melanomas and renal cell carcinomas. In this study, we have assessed whether peripheral blood CD4+ T cells from human histocompatibility leukocyte antigens (HLA)-DRβ1*0401+ patients are Th1- or Th2-biased to MAGE-6 epitopes using interferon (IFN)-γ and interleukin (IL)-5 enzyme-linked immunospot assays, respectively. Strikingly, the vast majority of patients with active disease were highly-skewed toward Th2-type responses against MAGE-6–derived epitopes, regardless of their stage (stage I versus IV) of disease, but retained Th1-type responses against Epstein-Barr virus– or influenza-derived epitopes. In marked contrast, normal donors and cancer patients with no current evidence of disease tended to exhibit either mixed Th1/Th2 or strongly Th1-polarized responses to MAGE-6 peptides, respectively. CD4+ T cell secretion of IL-10 and transforming growth factor (TGF)-β1 against MAGE-6 peptides was not observed, suggesting that specific Th3/Tr-type CD4+ subsets were not common events in these patients. Our data suggest that immunotherapeutic approaches will likely have to overcome or complement systemic Th2-dominated, tumor-reactive CD4+ T cell responses to provide optimal clinical benefit

Pilot trial of a type I - polarized autologous dendritic cell vaccine incorporating tumor blood vessel antigen-derived peptides in patients with metastatic breast cancer

Cancer vaccines based on tumor-associated antigens are rarely curative in advanced cancer. This limitation relates to the heterogeneity of cancer due to defects in antigen presentation and altered immunophenotypes. Therefore, another method to promote anti-tumor immunity is to prime T cells against tumor-associated stromal cells. We have reported [1] that IL-12 gene therapy of established HLA-A2neg B16 melanomas in HLA-A2+ transgenic mice resulted in CD8+ T cell-mediated immunity against the host HLA-A2+ stromal cells within the tumor microenvironment (TME). We have also shown [2] that vaccines based on a subset of tumor blood vessel antigen (TBVA)-derived peptides (DLK1, EphA2, HBB, NRP1, PDGFRβ, RGS5 or TEM1) prevented HLA-A2neg MC38 tumor establishment and promoted the regression of tumors in HLA-A2+ mice by CD8+ T cell targeting of HLA-A2+ pericytes and vascular endothelial cells in the TME. Based on this pre-clinical data, we propose to undertake a Susan G. Komen -funded (IIR13261822) clinical trial of chemo-immunotherapy using the immunomodulatory drug gemcitabine with a dendritic cell vaccine pulsed with six HLA-A2-presented TBVA-derived peptides (DLK1310-318, EphA2883-891, HBB31-39, NRP1433-441, RGS55-13 and TEM1691-700) in 30 HLA-A2+ patients with metastatic breast cancer. The specific aims of this study are to determine vaccine-induced generation of TBVA-Tc1 immunity and clinical response

Accumulation of MDSC subsets in renal cell carcinoma correlates with grade and progression free survival, and is associated with intratumoral expression of IL-1β, IL-8 and CXCL5

Myeloid derived suppressor cells (MDSC, CD33+CD11b+ HLA-DR low/-) play a major role in tumor-mediated immune evasion and are composed of at least 3 subsets PMN (CD15+), monocytic (CD14+) and lineage-negative (CD15-CD14-), and each has been shown to be significantly increased in some human tumor types and to correlate with metastatic burden, clinical cancer stage and outcome. Less in known about the MDSC subsets that accumulate in tumors such as renal cell carcinoma (RCC) and the cytokines/chemokines involved in their recruitment. Flow cytometry analysis of peripheral blood mononuclear cells (PBMC, n = 20) and nephrectomy samples (n = 39, stage 1-4) showed increased levels of total MDSC in RCC patients compared to normal controls (n = 15), with PMN- and Lin- MDSC subsets dominating in the blood and tumor of RCC patients. Blood levels of total MDSC, PMN-MDSC and Lin-MDSC correlated with tumor grade (p = 0.026, p = 0.006 and p = 0.045, respectively), while blood levels of total MDSC and Lin-MDSC correlated with progression free survival (PFS) in patients with limited stage disease (n = 16, stages 1-3) (HR = 1.35, p = 0.03; HR = 1.45, p = 0.02, respectively). In the tumor, higher PMN-MDSC levels were significantly associated with decreased PFS (n = 29, HR = 1.09, p = 0.011). To assess the role of select chemokines (IL-8, CXCL5, Mip-1α, MCP-1 and Rantes) and of the pro-inflammatory cytokine IL-1β in promoting the accumulation of MDSC within the tumor, these proteins were quantitated in tumor lysates by ELISA and correlated to MDSC frequencies (Spearman correlations). We found a direct correlation between the frequency of PMN-MDSC in the parenchyma and the levels of IL-8 (p < 0.001), CXCL-5 (p < 0.001), and IL-1β (p = 0.029). Frequency of parenchymal Lin- MDSC directly correlated with levels of IL-8 (p = 0.033) and CXCL-5 (p = 0.008), but not IL-1β. In circulation, frequency of total MDSCs directly correlated with IL-1β plasma levels (p = 0.003).\ud \ud To further define the role of IL-1β in MDSC accumulation within tumors, we overexpressed IL-1β in RENCA and CT26 tumors and compared them to untransfected tumors. Overexpression of IL-1β resulted in enhanced tumor growth and increased frequency of intratumor PMN-MDSC (10.3X in RENCA and 26X in CT26), with a modest increase in intratumor M-MDSC. A large fraction of tumor infiltrating PMN-MDSC expressed CXCR2 (84% in RENCA and 55% in CT26), which is associated with a significant increase in expression of CXCR2 ligands (KC, CXCL5, and MIP2). These results support the idea that IL-1β-mediated induction of select chemokines promotes the accumulation of MDSC, particularly PMN-MDSC, within tumors, resulting in enhanced immune suppression and angiogenesis

Modulation of Immune Effector and Regulator Cells by Sunitinib: Potential for Combination Therapy in Renal Cell Carcinoma Patients

No abstract availabl