Anisotropic interface magnetoresistance in Pt/Co/Pt sandwiches.

We report on an effect of reduced dimensionality on the magnetotransport in cobalt layers sandwiched by platinum. In a current in-plane geometry it is found that the resistivity depends on the magnetization orientation within the plane perpendicular to the current direction. The resistivity shows a symmetry adapted cos(2) dependence on the angle to the surface normal, with the maximum along the surface normal. The Co thickness dependence of the effect in Pt/Co/Pt sandwiches clearly points out that the mechanism behind this effect originates at the Co/Pt interfaces and is disparate to the texture induced geometrical size effect.

Race track memories seen from an Ab initio point of view.

In using the fully relativistic versions of the screened Korringa-Kohn-Rostoker method and of the Kubo-Greenwod equation equilibrium domain wall widths and corresponding domain wall resistivities are calculated for CocFe1-c and CocNi1-c making use of a multiscale approach. It is found that in CocFe1-c the domain wall width becomes rather large at about c = 0.4, but does not show an obvious singularity in the vicinity of the bcc to fcc phase transition. In CocNi1-c the domain wall width varies much less in size with respect to the concentration. In particular, it is demonstrated that as compared to the homogeneous infinite systems the anisotropic magnetoresistance is reduced in the presence of a domain wall. This reduction is rather big for CocNi1-c, namely, about 6%, while for CocFe1-c it is only of the order of 1%-2%. The results clearly indicate that CocNi1-c might be a useful candidate for race track memories.

Domain wall formation in NixFe1-x.

In terms of a multiscale approach based on the Landau-Ginzburg expansion and on ab initio parameters evaluated by means of the fully relativistic screened Korringa-Kohn-Rostoker method, the width of domain walls is evaluated for the whole range of concentration in NixFe1-x. It is found that domain-wall formation occurs only for x<20% and x>55%; i.e., in the neighborhood of the structural phase transition from bcc to fcc, NixFe1-x first tends to form single domains before the actual range of concentrations of this phase transition is reached. The calculated domain-wall widths are found to be in reasonably good agreement with available experimental data.

Automated quantitative analysis of DCC tumor suppressor protein in ovarian cancer tissue microarray shows association with beta-catenin levels and outcome in patients with epithelial ovarian cancer.

BACKGROUND: The deleted in colorectal cancer (DCC) protein, the product of DCC tumor suppressor gene, is frequently altered in cancer. Preclinical data demonstrate that DCC regulates beta-catenin levels. Here, we sought to determine the association of DCC with beta-catenin protein levels, clinicopathological parameters and patient outcome in ovarian cancer using a method of in situ compartmentalized protein analysis. METHODS: A tissue array composed of 150 advanced-stage ovarian cancers, treated with surgical debulking and platinum-paclitaxel (Taxol) combination chemotherapy, was constructed. For evaluation of protein expression, we used an immunofluorescence-based method of automated in situ quantitative measurement of protein analysis (AQUA). RESULTS: One hundred and twelve patients (74%) had sufficient tissue for AQUA. The median follow-up time for the entire cohort was 33 months. Patients with low nuclear DCC expression had a 3-year progression-free survival (PFS) rate of 0% compared with 33% of those with high DCC expression (P = 0.0067). In multivariate analysis, low nuclear DCC expression level retained its prognostic significance for PFS. Between DCC and beta-catenin, a significant relationship was found, where tumors with low DCC had low beta-catenin and vice versa (P = 0.003). CONCLUSIONS: Low nuclear DCC levels predict for poor patient outcome in epithelial ovarian cancer. DCC may exert its antitumor function, in part, through regulation of beta-catenin levels.

Cisplatin, fluorouracil, and leucovorin induction chemotherapy followed by concurrent cisplatin chemoradiotherapy for organ preservation and cure in patients with advanced head and neck cancer: long-term follow-up.

PURPOSE: The poor functional outcome in patients with advanced head and neck squamous cell carcinoma (HNSCC) with surgery and radiation has led to alternative approaches to advanced disease. We conducted a phase II study of induction chemotherapy followed by concurrent chemoradiotherapy for organ preservation in patients with advanced resectable and unresectable (nasopharyngeal) tumors. PATIENTS AND METHODS: Forty-two patients with stage III to IV resectable HNSCC and nasopharyngeal tumors received induction chemotherapy with two courses of cisplatin (20 mg/m2/d continuous infusion [CI]), fluorouracil (800 mg/m2/d CI), and leucovorin (500 mg/m2/d CI; PFL) for 4 days followed by concurrent therapy with cisplatin (100 mg/m2/d on days 1 and 22) and approximately 70 Gy of external-beam radiotherapy. RESULTS: Response to induction chemotherapy included partial response rate of 52% and complete response rate of 24%. The most common grade 3 or 4 toxicity was neutropenia (59%). After cisplatin chemoradiotherapy the complete response rate was 67%. Toxicities of cisplatin chemoradiotherapy consisted of grade 3 or 4 mucositis (79%) and neutropenia (51%). At a median follow-up of 71.5 months, 43% of the patients are still alive and disease-free. The 5-year progression-free survival (PFS) rate was 60%, and the 2- and 5-year overall survival (OS) rates were 67% and 52%, respectively. Three patients died of second primaries. Late complications of treatment included xerostomia and hoarseness. One patient had persistent dysphagia and required laser epiglotectomy 108 months after treatment. CONCLUSION: Induction chemotherapy with PFL followed by concurrent cisplatin chemoradiotherapy is well tolerated and results in a good likelihood of organ preservation and excellent PFS and OS.

Enzyme-mimetic model compounds: conformational analysis and far-IR study of Cu(TAAB)2+.

Many enzymes occurring in nature like superoxide dismutase are systems rather too big to be accessible for vibrational and quantum chemical investigations. Thus, enzyme-mimetic model compounds consisting of a biological active metal centre surrounded by a macrocyclic ligand are used to shed light on binding properties of the active metal centre. Far- and mid-range IR spectroscopic investigations and a conformational analysis with the semi-empirical ZINDO/1 method of superoxide dismutase-mimetic complex Cu[TAAB]2+ are performed (TAAB = [b,f,j,n][1,5,9,13]tetra-aza-cyclohexadecine (tetra-anhydroamino benzaldehyde)). A distorted tetrahedral copper(II) centre with slightly twisted phenyl subunits is determined as the most stable conformation. Calculated mid- and far-IR spectra are in good agreement with the experimental data and confirm the proposed structure. A harmonic normal-coordinate analysis is used to assign the vibrational modes of the observed spectra.