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.

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.

The involvement of topoisomerases and DNA polymerase I in the mechanism of induced thermal and radiation resistance in yeast.

Either an ionizing radiation exposure or a heat shock is capable of inducing both thermal tolerance and radiation resistance in yeast. Yeast mutants, deficient in topoisomerase I, in topoisomerase II, or in DNA polymerase I, were used to investigate the mechanism of these inducible resistances. The absence of either or both topoisomerase activities did not prevent induction of either heat or radiation resistance. However, if both topoisomerase I and II activities were absent, the sensitivity of yeast to become thermally tolerant (in response to a heat stress) was markedly increased. The absence of only topoisomerase I activity (top1) resulted in the constitutive expression of increased radiation resistance equivalent to that induced by a heat shock in wild-type cells, and the topoisomerase I-deficient cells were not further inducible by heat. This heat-inducible component of radiation resistance (or its equivalent constitutive expression in top1 cells) was, in turn, only a portion of the full response inducible by radiation. The absence of polymerase I activity had no detectable effect on either response. Our results indicate that the actual systems that confer resistance to heat or radiation are independent of either topoisomerase activity or DNA polymerase function, but suggest that topoisomerases may have a regulatory role during the signaling of these mechanisms. The results of our experiments imply that maintenance of correct DNA topology prevents induction of the heat-shock response, and that heat-shock induction of a component of the full radiation resistance in yeast may be the consequence of topoisomerase I inactivation.

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.

Lemna minor membranes affected by adjuvants.

The perturbant effects of four Triton adjuvants, namely Triton X-15, X-35, X-100, and X-114 (alkyl aryl polyether alcohols), on some of the biochemical determinants of membrane integrity were determined under laboratory conditions. Two of these, Triton X-100 and X-114, are currently being assessed as emulsifiers for use in fenitrothion insecticidal formulations. Lemna minor L. plants were exposed to 40 microM (10-25 microg ml(-1) in 965 microg mg(-1) Dowanol (tripropylene glycol methyl ether) carrier solvent) adjuvant for a treatment time period of two weeks. A decrease in the contents of the total phospholipids and a concomitant increase in the contents of the galactolipids were found. No change was observed in the total lipid content. An unsaturation occurred in the fatty acids of the total lipids, phospholipids, and monogalactosyl diacylglycerides. This accounted for a significant decrease in palmitic and stearic acids and a concomitant increase in oleic, linoleic, and linolenic acids when these are compared with the fatty acids in the nontreated control sets. The fatty-acid profile of the digalactosyl diacylglycerides, however, differed only slightly from controls. Membrane-fatty-acid unsaturation suggests the possibility of a desaturase enzyme's being induced by these adjuvants.