Rodent models for experimental heat stroke research

Because of the aggressive threaten of heat stroke and a lack of understanding of the mechanism of action, mammal animal models for experimental heat stroke were well developed. During the past 5 decades, anesthetized mouse, rat, rabbit, dog, baboon and monkey were used as animal model for experimental heat stroke. However, anesthetized mammals models have some limitations, such as neuroprotective effect of anesthetic agents, possible disturbance on injury and recovery of stroke animals by anesthetic agents, difficulty of discussing animal behavior before and after heat stroke, it was also difficult for the models to evaluate cognitive function of animal under hot environment. Considering humanitarian, only awaked and unrestrained mouse heat stroke model was accepted so far. Therefore, we also developed an awaked and unrestrained rat heat stroke model, and found it was helpful to evaluate drug effectiveness for animal behavior and cognitive function under hot environment.

Quinacrine pretreatment reduces microwave-induced neuronal damage by stabilizing the cell membrane

Quinacrine, widely used to treat parasitic diseases, binds to cell membranes. We previously found that quinacrine pretreatment reduced microwave radiation damage in rat hippocampal neurons, but the molecular mechanism remains poorly understood. Considering the thermal effects of microwave radiation and the protective effects of quinacrine on heat damage in cells, we hypothesized that quinacrine would prevent microwave radiation damage to cells in a mechanism associated with cell membrane stability. To test this, we used retinoic acid to induce PC12 cells to differentiate into neuron-like cells. We then pretreated the neurons with quinacrine （20 and 40 mM） and irradiated them with 50 mW/cm^2 microwaves for 3 or 6 hours. Flow cytometry, atomic force microscopy and western blot assays revealed that irradiated cells pretreated with quinacrine showed markedly less apoptosis, necrosis, and membrane damage, and greater expression of heat shock protein 70, than cells exposed to microwave irradiation alone. These results suggest that quinacrine stabilizes the neuronal membrane structure by upregulating the expression of heat shock protein 70, thus reducing neuronal injury caused by microwave radiation.

Shear bond strengths between alumina-toughened zirconia cores and veneering ceramics and their susceptibility to aging

Objective:To evaluate the shear bond strength(SBS) between alumina-toughened zirconia (ATZ) cores and veneering ceramics,investigate the effect of aging in artificial saliva on SBS and compare it with that of yttria-stabilized tetragonal zirconia polycrystals(Y-TZP).Methods:Bars of ATZ and Y-TZP were layered with veneering ceramics in accordance to the recommendation of the manufacturer.Half of each group(n = 10) was aged at 134℃.(under 2 bar pressure) in an autoclave for 48 h.Subsequently,all specimens were subjected to shear force in a universal testing machine.The interface and fractured surface of the specimens were evaluated using scanning electron microscopy and X-ray energy dispersive spectroscopy.Results:The initial mean SBS values in MPa±SD were 28.9±8.0 for ATZ and 26.2±7.6 for Y-TZP.After aging,the mean SBS values for ATZ and Y-TZP were 22.9±4.9 MPa and 22.8±6.9 MPa,respectively.Neither the differences between the SBS values of the ATZ and Y-TZP groups nor the influence of aging on all groups were statistically significant.Conclusions:The SBS between the ATZ core and the veneering ceramics was not affected by aging.The SBS of ATZ to veneering ceramics was not significantly different compared with that of Y-TZP.

Electrical properties of a generalized 2×n resistor network

Any changes in resistor conditions will increase the difficulty of resistor network research.This paper considers a new model of a generalized 2×n resistor network with an arbitrary intermediate axis that was previously unsolved.We investigate the potential function and equivalent resistance of the 2×n resistor network using the RT-I theory.The RT-I method involves four main steps:(1)establishing difference equations on branch currents,(2)applying a matrix transform to study the general solution of the differential equation,(3)obtaining a current analysis of each branch according to the boundary constraints,and(4)deriving the potential function of any node of the 2×n resistor network by matrix transformation,and the equivalent resistance formula between any nodes.The article concludes with a discussion of a series of special results,comparing and verifying the correctness of the conclusions.The work establishes a theoretical basis for related scientific research and application.

Cortical Inflammation is Increased in a DSS-Induced Colitis Mouse Model

While inflammatory bowel disease(IBD) might be a risk factor in the development of brain dysfunctions,the underlying mechanisms are largely unknown. Here,mice were treated with 5% dextran sodium sulfate(DSS) in drinking water and sacrificed on day 7. The serum level of IL-6 increased, accompanied by elevation of the IL-6 and TNF-a levels in cortical tissue. However, the endotoxin concentration in plasma and brain of mice with DSSinduced colitis showed a rising trend, but with no significant difference. We also found significant activation of microglial cells and reduction in occludin and claudin-5 expression in the brain tissue after DSS-induced colitis.These results suggested that DSS-induced colitis increases systemic inflammation which then results in cortical inflammation via up-regulation of serum cytokines. Here,we provide new information on the impact of colitis on the outcomes of cortical inflammation.