Chemical nanoroughening of Ti40Nb surfaces and its effect on human mesenchymal stromal cell response.

Samples of low modulus beta-type Ti40Nb and cp2-Ti were chemically treated with 98% H2 SO4 + 30% H2 O2 (vol. ratio 1:1) solution. Surface analytical studies conducted with HR-SEM, AFM, and XPS identified a characteristic nanoroughness of the alloy surface related with a network of nanopits of ∼25 nm diameter. This is very similar to that obtained for cp2-Ti. The treatment enhances the oxide layer growth compared to mechanically ground states and causes a strong enrichment of Nb2 O5 relative to TiO2 on the alloy surface. The in vitro analyses clearly indicated that the chemical treatment accelerates the adhesion and spreading of human mesenchymal stromal cells (hMSC), increases the metabolic activity, and the enzyme activity of tissue non-specific alkaline phosphatase (TNAP). Surface structures which were generated mimic the cytoplasmic projections of the cells on the nanoscale. Those effects are more pronounced for the Ti40Nb alloy than for cp2-Ti. The relation between alloy surface topography and chemistry and cell functions is discussed.

[Influenza vaccination rates in Hessian hospitals]. / Influenzaimpfquoten in hessischen Krankenhäusern.

Influenza infections have been shown to spread in hospitals rapidly; nosocomial transmissions occur frequently. Influenza vaccination of health care personnel (HCP) is an effective strategy for preventing influenza infections among personnel and patients. In summer 2011 we conducted an anonymous questionnaire among Hessian hospitals assessing influenza vaccination rates, kind and concept of vaccination programmes. Overall, 95.8% (68/71) of hospitals surveyed offered influenza vaccinations for HCP free of charge. Influenza vaccination rates have been recorded only by 70.4% (50/71). Over 80% (season 2009/2010: 41/50- season 2010/2011: 44/50) of hospitals questioned, mentioned influenza vaccination rates under 20%. Our findings confirm that the influenza vaccination rates might be less than the generally assumed and communicated influenza vaccination rates of 20-25%. Thirty years since the German Standing Committee on Vaccination (STIKO) recommended that all HCP get vaccinated against influenza, vaccination rates still remain below 30%. Measures to improve influenza vaccination rates among HCP are required. Monitoring of vaccination rates is a precondition to assess the acceptance of a vaccination programme.

Magnetic films on nanoperforated templates: a route towards percolated perpendicular media.

We present a study on the magnetization reversal in Co/Pt multilayer films with an out-of-plane easy axis of magnetization deposited onto substrates with densely distributed perforations with an average period as small as 34 nm. Deposition of magnetic Co/Pt multilayers onto the nanoperforated surface results in an array of magnetic nanodots surrounded by a continuous magnetic film. Following the evolution of the magnetic domain pattern in the system, we suggest that domain walls are pinned on structural inhomogeneities given by the underlying nanoperforated template. Furthermore, a series of micromagnetic simulations was performed in order to understand the modification of the pinning strength of domain walls due to the magnetic interaction between nanodots and the surrounding film. The results of the simulations show that magnetic exchange coupling between the nanodots and the surrounding film strongly influences the pinning behavior of the magnetic domain walls which can be optimized to provide maximal pinning.

Electronic phase separation in the slightly underdoped iron pnictide superconductor Ba1-xKxFe2As2.

Here we present a combined study of the slightly underdoped novel pnictide superconductor Ba1-xKxFe2As2 by means of x-ray powder diffraction, neutron scattering, muon-spin rotation (microSR), and magnetic force microscopy (MFM). Static antiferromagnetic order sets in below T{m} approximately 70 K as inferred from the neutron scattering and zero-field-microSR data. Transverse-field microSR below Tc shows a coexistence of magnetically ordered and nonmagnetic states, which is also confirmed by MFM imaging. We explain such coexistence by electronic phase separation into antiferromagnetic and superconducting- or normal-state regions on a lateral scale of several tens of nanometers. Our findings indicate that such mesoscopic phase separation can be considered an intrinsic property of some iron pnictide superconductors.

Characterization of oxide layers on amorphous Mg-based alloys by Auger electron spectroscopy with sputter depth profiling.

Amorphous ribbons of Mg-Y-TM-[Ag] (TM: Cu, Ni), prepared by melt spinning, were subjected to electrochemical investigations. Oxide layers formed anodically under potentiostatic control in different electrolytes were investigated by AES and sputter depth profiling. Problems and specific features of characterization of the composition of oxide layers and amorphous ternary or quaternary Mg-based alloys have been investigated. In the alloys the Mg(KL(23)L(23)) peak exhibits a different shape compared to that in the pure element. Analysis of the peak of elastically scattered electrons proved the absence of plasmon loss features, characteristic of pure Mg, in the alloy. A different loss feature emerges in Mg(KL(23)L(23)) and Cu(L(23)VV). The system Mg-Y-TM-[Ag] suffers preferential sputtering. Depletion of Mg and enrichment of TM and Y are found. This is attributed mainly to the preferential sputtering of Mg. Thickness and composition of the formed oxide layer depend on the electrochemical treatment. After removing the oxide by sputtering the concentration of the underlying alloy was found to be affected by the treatment.

[MRI-assisted brachytherapy of nonresectable liver metastases. Preliminary technical and clinical experiences]. / MR-gestützte Brachytherapie nichtresektabler Lebermetastasen. Vorläufige technische und klinische Erfahrungen.

PURPOSE: To evaluate the feasibility and efficacy of MR-guided interstitial brachytherapy of non-resectable liver metastasis. METHODS: Liver metastases (0.8-5.2 cm in diameter) were treated during a prospective phase I/II study using an open 0.2 Tesla MR system (Magnetom Open Viva, Siemens, Erlangen). MR-compatible brachytherapy applicators were placed percutaneously under MR-guidance in an open 0.2 Tesla MR system (Magnetom Open Viva, Siemens, Erlangen) using fast T1-weighted sequences. Pretreatment and follow-up studies were performed using a 1.5 Tesla MR system. RESULTS: Preliminary results of an unpublished prospective study are discussed exemplary on 2 selected patients. The median procedure time was 4.9 h. No major complications were observed and late effects were acceptable. In large symptomatic metastases only a temporary relief of pain was achieved. In smaller metastases (DM 3 cm) a tumor control was observed. CONCLUSION: MR-guided brachytherapy is feasible and has the potential to ablate liver metastases with diameter of less than 3 cm. Further developments are necessary.

p53-dependent radioresistance in ovarian carcinoma cell lines.

In the present study, we investigated the radiosensitivity profiles of three established human ovarian carcinoma cell lines, PA-1, Caov-3, and SK-OV-3, using the adenosine triphosphate-cell viability assay (ATP-CVA). We have correlated radioresponsiveness with the p53 status and the p53 accumulation after irradiation as well as with the Bcl-2 expression and the growth rate of these cell lines. The p53 status was examined by immunocytochemistry and a functional assay (functional analysis of separated alleles in yeast, FASAY); the p53 accumulation was determined by immunocytochemistry and flow cytometry. Furthermore, the Bcl-2 expression before and after irradiation was examined by immunocytochemistry. PA-1, expressing wild-type p53, showed an unequivocal accumulation of p53 protein following exposure to irradiation. This cell line was found to be strongly sensitive to irradiation. The two p53 mutant cell lines Caov-3 and SK-OV-3 showed radioresistance at different degrees and irradiation did not result in p53 accumulation. None of the cell lines examined expressed Bcl-2 protein and no change was seen after irradiation. Furthermore, the most sensitive cell line to irradiation, PA-1, showed the highest proliferative activity, while Caov-3 and SK-OV-3, the more resistant cell lines, exhibited lower growth rates. Our findings indicate that the presence of p53 protein is a possible determinant for the cytotoxicity induced by irradiation in the investigated ovarian carcinoma cell lines. Bcl-2 expression does not seem to determine the response to irradiation in these cell lines. Additionally, an association between radioresponsiveness and the growth rate is suggested in PA-1, Caov-3, and SK-OV-3.

Quinolobactin, a new siderophore of Pseudomonas fluorescens ATCC 17400, the production of which is repressed by the cognate pyoverdine.

Transposon mutant strain 3G6 of Pseudomonas fluorescens ATCC 17400 which was deficient in pyoverdine production, was found to produce another iron-chelating molecule; this molecule was identified as 8-hydroxy-4-methoxy-quinaldic acid (designated quinolobactin). The pyoverdine-deficient mutant produced a supplementary 75-kDa iron-repressed outer membrane protein (IROMP) in addition to the 85-kDa IROMP present in the wild type. The mutant was also characterized by substantially increased uptake of (59)Fe-quinolobactin. The 75-kDa IROMP was produced by the wild type after induction by quinolobactin-containing culture supernatants obtained from the pyoverdine-negative mutant or by purified quinolobactin. Conversely, adding purified wild-type pyoverdine to the growth medium resulted in suppression of the 75-kDa IROMP in the pyoverdine-deficient mutant; however, suppression was not observed when Pseudomonas aeruginosa PAO1 pyoverdine, a siderophore utilized by strain 3G6, was added to the culture. Therefore, we assume that the quinolobactin receptor is the 75-kDa IROMP and that the quinolobactin-mediated iron uptake system is repressed by the cognate pyoverdine.

Portal imaging based definition of the planning target volume during pelvic irradiation for gynecological malignancies.

PURPOSE: Geometrical accuracy in patient positioning can vary substantially during external radiotherapy. This study estimated the set-up accuracy during pelvic irradiation for gynecological malignancies for determination of safety margins (planning target volume, PTV). METHODS AND MATERIALS: Based on electronic portal imaging devices (EPID), 25 patients undergoing 4-field pelvic irradiation for gynecological malignancies were analyzed with regard to set-up accuracy during the treatment course. Regularly performed EPID images were used in order to systematically assess the systematic and random component of set-up displacements. Anatomical matching of verification and simulation images was followed by measuring corresponding distances between the central axis and anatomical features. Data analysis of set-up errors referred to the x-, y-,and z-axes. Additionally, cumulative frequencies were evaluated. RESULTS: A total of 50 simulation films and 313 verification images were analyzed. For the anterior-posterior (AP) beam direction mean deviations along the x- and z-axes were 1.5 mm and -1.9 mm, respectively. Moreover, random errors of 4.8 mm (x-axis) and 3.0 mm (z-axis) were determined. Concerning the latero-lateral treatment fields, the systematic errors along the two axes were calculated to 2.9 mm (y-axis) and -2.0 mm (z-axis) and random errors of 3.8 mm and 3.5 mm were found, respectively. The cumulative frequency of misalignments < or =5 mm showed values of 75% (AP fields) and 72% (latero-lateral fields). With regard to cumulative frequencies < or =10 mm quantification revealed values of 97% for both beam directions. CONCLUSION: During external pelvic irradiation therapy for gynecological malignancies, EPID images on a regular basis revealed acceptable set-up inaccuracies. Safety margins (PTV) of 1 cm appear to be sufficient, accounting for more than 95% of all deviations.

Theory and application of passive SAW radio transponders as sensors.

Surface acoustic wave (SAW) radio transponders make it possible to read identification codes or measurement values from a remote location. The decisive advantage of these SAW transponders lies in their passive operation (i.e., no power-supply), and in the possibility of wireless installation at particularly inaccessible locations. The passive SAW transponders are maintenance free. Identification marks respond to an interrogation signal with their nonchanging identification pattern. In wireless SAW sensors the physical or chemical properties to be detected change the propagation characteristics of the SAW. SAW radio transponders are advantageously placed on moving or rotating parts and in hazardous environments such as contaminated or high voltage areas. They also can be used for contactless measurements in high vacuum process chambers, under concrete, extreme heat, or strong radioactive radiation, where the use of conventional sensors is complicated, dangerous, or expensive. In this paper we discuss the principles of wireless passive SAW transponders and present a radio frequency interrogation unit and several passive radio SAW sensors developed for noncontact measurements of temperatures, pressures, torques, and currents.

Dosimetric comparison of an integrated multileaf-collimator versus a conventional collimator.

The dosimetric characteristics of both a conventional GE collimator (CC) and a GE multileaf collimator (MLC) are compared for different photon beam energies. The integrated GE MLC consists of 32 pairs of tungsten leaves, replacing the lower pair of jaws of the conventional collimator. Measurements were performed with the conventional collimator before this collimator was replaced by the MLC. All parts of the accelerator except the collimator remained the same. Leakage and transmission measurements show good agreement with the manufacturer's specification, stating a leakage between leaves of less than 1% for all energies and a transmission through leaves of less than 0.5%. The dosimetric characteristics of both collimators are very similar for square and rectangular fields. No significant change in beam quality, beam attenuation and depth of maximum dose could be detected within the measurement accuracy. The MLC output ratio variation is smaller than the one measured with the CC. The penumbra difference in the Y direction is less than 0.5 mm at a depth of 5 cm in phantom; in the X direction the penumbra is 1 mm larger for the MLC due to the rounded leaf fronts. As the two leaf banks replace the lower pair of collimator jaws the distance from the collimator end to the isocentre is similar for the two collimators, therefore the MLC does not reduce the flexibility of the treatment unit. For symmetrical and regular collimator settings the MLC can be treated as the CC.

Blue-yellow deficiency in workers exposed to low concentrations of organic solvents.

OBJECTIVES: To evaluate the effects of low concentrations of organic solvents on color vision. METHODS: Color vision was examined in 24 workers exposed to mixtures of solvents and in 24 control subjects. Exposure to mixtures was below the threshold-limit values. Color vision ability was assessed using the Ishihara plates (to screen for congenital dyschromatopsia), the Farnsworth panel D-15 test, the Lanthony desaturated panel D-15 test, and the Standard Pseudoisochromatic Plates part 2 (SPP2 test). RESULTS: The comparatively less sensitive Farnsworth panel D-15 test failed to show any difference between the groups, but the Lanthony panel D-15 desaturated test as well as the SPP2 test showed a significant impairment in the exposed group. Errors were of the blue-yellow type. CONCLUSION: This study gives further evidence that even mixtures of organic solvents at concentrations below the threshold-limit values may impair color vision.