Expression and function of selenoproteins in endocrine tissues remain unclear, largely due to limited sample availability. Pigs have a greater metabolic similarity and tissue size than rodents as a model of humans for that purpose. We conducted 2 experiments: 1) we cloned 5 novel porcine selenoprotein genes; and 2) we compared the effects of dietary selenium (Se) on mRNA levels of 12 selenoproteins, activities of 4 antioxidant enzymes, and Se concentrations in testis, thyroid, and pituitary with those in liver of pigs. In Experiment 1, porcine Gpx2, Sephs2, Sep15, Sepn1, and Sepp1 were cloned and demonstrated 84-94% of coding sequence homology to human genes. In Experiment 2, weanling male pigs (n = 30) were fed a Se-deficient (0.02 mg Se/kg) diet added with 0, 0.3, or 3.0 mg Se/kg as Se-enriched yeast for 8 wk. Although dietary Se resulted in dose-dependent increases (P < 0.05) in Se concentrations and GPX activities in all 4 tissues, it did not affect the mRNA levels of any selenoprotein gene in thyroid or pituitary. Testis mRNA levels of Txnrd1 and Sep15 were decreased (P < 0.05) by increasing dietary Se from 0.3 to 3.0 mg/kg. Comparatively, expressions of Gpx2, Gpx4, Dio3, and Sep15 were high in pituitary and Dio1, Sepp1, Sephs2, and Gpx1 were high in liver. In conclusion, the mRNA abundances of the 12 selenoprotein genes in thyroid and pituitary of young pigs were resistant to dietary Se deficiency or excess.

The pathological lesions induced by multiwalled carbon nanotubes (MWCNTs) in bronchi and alveoli of mice were studied by intratracheal instillation and inhalation. In instillation groups, the dose was 0.05 mg MWCNTs/mouse. Similar size clumps of MWCNTs were distributed in bronchi and alveoli. The clumps led to inflammation to the lining wall of bronchi and severe destruction to alveolar netted structure around them. In the inhalation groups, the mice were exposed to aerosolized MWCNTs with mean concentration of 32.61 mg/m(3), the intralung deposition dose were roughly 0.07, 0.14, and 0.21 mg in the 8-day group, 16-day group, and 24-day group, respectively. Most of aggregations of MWCNTs in the alveoli were smaller than that in bronchi. The aggregations induced proliferation and thickening of alveolar walls. With the exception of these moderate pathological lesions, the general alveolar structure was still remained. The preliminary study demonstrated a difference in lung pathological lesions induced by instilled MWCNTs and inhaled ones, which may be due to the different size and distribution of aggregations of MWCNTs in lung.

With an integrated resonance exciting heater and a self-sensing piezoresistor, resonant micro-cantilever bio/chemical sensors are optimally designed and fabricated by micromachining techniques. This study is emphasized on the optimization of the integrated heating resistor. Previous research has put the heater at either the cantilever clamp end, the midpoint or the free end. Aiming at sufficiently high and stable resonant amplitude, our research indicates that the optimized location of the thermal-electric exciting resistor is the clamp end instead of other positions. By both theoretical analysis and resonance experiments where three heating resistors are placed at the three locations of the fabricated cantilever, it is clarified that the clamp end heating provides the most efficient resonance excitation in terms of resonant amplitude, Q-factor and resonance stability. Besides, the optimized combination of dc bias and ac voltage is determined by both analysis and experimental verification. With the optimized heating excitation, the resonant cantilever is used for biotin–avidin-specific detection, resulting in a ±0.1 Hz ultra-low noise floor of the frequency signal and a 130 fg mass resolution. In addition to resonance excitation, the heater is used to heat up the cantilever for speed-up desorption after detection that helps rapid and repeated sensing to chemical vapor. The clamp end is determined (by simulation) as the optimal heating location for uniform temperature distribution on the cantilever. Using the resonant cantilever, a rapid and repeated sensing experiment on dimethyl methylphosphonate (DMMP) vapor shows that a short-period heating at the detection interval significantly quickens the signal recovery and enhances the sensing repeatability.

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