Mesenchymal stem cells (MSCs) have great potential for repair following acute myocardial infarction. However, a major challenge to MSC therapy is that transplanted cells undergo apoptosis. Hydrogen sulfide (H2S) has recently been proposed as an endogenous mediator of cell apoptosis in various systems. The aim of the present study was to investigate the role of endogenous H2S in hypoxia and serum deprivation (hypoxia/SD)-induced apoptosis in MSCs. The present study demonstrated that exposure of MSCs to hypoxia/SD caused a significant decrease in H2S generation and resulted in marked cell apoptosis. Furthermore, under basal conditions, MSCs expressed cystathionine γ-lyase (CSE) and synthesized H2S, whereas CSE expression and activity was inhibited by hypoxia/SD treatment. Overexpression of CSE not only markedly prevented hypoxia/SD-induced decreases in endogenous H2S generation but also protected MSCs from apoptosis, while inhibition of CSE by its potent inhibitors significantly deteriorated the effect of hypoxia/SD in MSCs. These data indicate that the H2S generation pathway exists in MSCs and the inhibition of the endogenous CSE/H2S system contributes to hypoxia/SD-induced apoptosis in MSCs. Our findings suggest that modulation of the CSE/H2S system is a potential therapeutic avenue for promoting the viability of transplanted MSCs.

Pleurotus ostreatus and a newly isolated Ganoderma lingzhi strain were evaluated for their laccase secretion capacity by solid-state fermentation with different agricultural and forestry residues. There was a significant difference among fungi for biosynthetic potential. In principle, the laccase secretion capacity of P. ostreatus CY 568 was stronger than that from G. lingzhi Han 500. Different species of fungi had a preference for agricultural and forestry residues. The presence of cottonseed hull and Populus beijingensis were helpful for accelerating the rate of laccase enzyme production of P. ostreatus CY 568. Cottonseed hull and corncob were useful for improving the production of laccase from G. lingzhi Han 500. Continuous and stable laccase production was found on cottonseed hull by P. ostreatus CY 568 and G. lingzhi Han 500. Maximum laccase activity obtained from P. ostreatus CY 568 on Toona sinensis, Sophora japonica, Salix babylonica, Populus beijingensis, corncob, cottonseed hull, and straw of Oryza sativa was higher than that from G. lingzhi Han 500, and was nearly 1.16-fold, 1.59-fold, 3.32-fold, 1.39-fold, 1.08-fold, 1.08-fold, and 1.36-fold, respectively. These findings will be helpful for developing new productive strains and expanding more species for industrial application to obtain efficient and low-cost laccase.

Realistic anatomical modeling is essential in analyzing human exposure to electromagnetic fields. Infants have significant physical and anatomical differences compared with other age groups. However, few realistic infant models are available. In this work, we developed one 12-month-old male whole body model and one 17-month-old male head model from magnetic resonance images. The whole body and head models contained 28 and 30 tissues, respectively, at spatial resolution of 1 mm × 1 mm × 1 mm. Fewer identified tissues in the whole body model were a result of the low original image quality induced by the fast imaging sequence. The anatomical and physical parameters of the models were validated against findings in published literature (e.g., a maximum deviation as 18% in tissue mass was observed compared with the data from International Commission on Radiological Protection). Several typical exposure scenarios were realized for numerical simulation. Dosimetric comparison with various adult and child anatomical models was conducted. Significant differences in the physical and anatomical features between adult and child models demonstrated the importance of creating realistic infant models. Current safety guidelines for infant exposure to radiofrequency electromagnetic fields may not be conservative.

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