Direct electrochemistry and electrocatalysis of hemoglobin immobilized in TiO2 nanotube films.

Titanium oxide nanotubes (TiO(2)-NTs) synthesized by the hydrothermal method had been prepared as the co-immobilization matrix to incorporate hemoglobin (Hb) successfully. The nanostructures of TiO(2)-NTs were investigated by X-ray diffraction and high-resolution electron microscopy. The Hb immobilized in TiO(2)-NTs had a similar structure to the native of Hb and retained its near-native conformations as characterized by the UV-vis and FT-IR spectroscopy. A couple of quasi-reversible redox peaks with a formal potential of -0.34 V (vs. SCE) in 0.10 M pH 7.0 phosphate buffered saline (PBS) were observed. The amperometric response of the immobilized Hb linearly to H(2)O(2) concentration ranged from 4 microM to 64 microM with a detection limit of 4.637 x 10(-6)M and the high stability of the immobilized Hb in TiO(2)-NTs constituted a promising platform for the development of biosensors.

Relationship between acoustic aperture size and tumor conditions for external ultrasound hyperthermia.

External ultrasound hyperthermia is a very flexible modality for heating deep-seated tumors due to its deep penetration and focusing ability. However, under the constraints of the available acoustic aperture size for the ultrasonic beam, ultrasonic attenuation, as well as other anatomic properties, it may not be able to deliver sufficient ultrasonic energy to heat a large tumor located in a deep region without overheating the normal tissue between the tumor and the aperture. In this work, we employ a simulation program based on the steady-state bioheat transfer equation and an ideal ultrasound power deposition (a cone with convergent/divergent shape) to examine the relationship between the minimal diameter of the acoustic aperture and the tumor conditions. Tissue temperatures are used to determine the appropriate aperture diameter and the input power level for a given set of tumor conditions. Due to the assumed central axis symmetry of the power intensity deposition and anatomic properties, a two-dimensional (r-z) simulation program is utilized. Factors determining the acoustic aperture diameter and the input power level considered here are the tumor size, tumor depth, ultrasonic attenuation in tissue, blood perfusion, and temperature of the surface cooling water. Simulation results demonstrate that tumor size, tumor depth, and ultrasonic attenuation are major factors affecting the aperture diameter of the ultrasonic beam to obtain an appropriate temperature distribution, while blood perfusion and the temperature of the surface cooling water are the minor factors. Plots of the effects of these factors can be used as the guideline for designing an optimal ultrasound heating system, arranging the transducers, and planning further treatments.

[Pathological survey of lung cancer induced by tin mine dust in Yunnan].

Pathological changes of lung cancer in miners of Yunnan Tin Mine were studied, and additionally, mineral dust in the miners' lung were also investigated by using scanning electronic microscope, energy disperse X-ray spectrometer and electronic probe. The results showed: 1. mineral dust caused active hyperplasia, atypical hyperplasia, metaplasia and atypical metaplasia of the epithelial of alveoli and bronchi, which was able to induce cancer. 2. Pneumoconiosis-like changes in the miner's lung are correlated with the high incidence of lung cancer. 3. Correlated also with copper, lead, zinc and iron may be the high incidence of lung cancer. 4. Transition form from hyperplasia and atypical hyperplasia of alveolar epithelia to malignancy was observed. It suggests that lung squamous cell carcinoma probably originates from the alveolar epithelia of the lung.