Molecular dynamics simulation of the transmembrane transport process of reactive species under the synergistic effect of plasma oxidation and an electric field.

Cold atmospheric pressure plasma (CAP)-assisted cancer therapy has become a popular topic in plasma biomedical research. Membrane lipid oxidation and local electric fields are two important factors in plasma-cell interactions, and the study of their synergistic effect is highly significant for optimizing the regulatory mechanism of the plasma-induced apoptosis of cancer cells. In this paper, a model of oxidized phospholipids was established, and the transmembrane process of reactive species was simulated by the classical molecular dynamics (MD) method under the conditions of oxidation and an electric field. The results showed that hydrophilic reactive oxygen species could not penetrate the membrane lipids through oxidation. The formation of electroporation provided a new channel for reactive species to penetrate the membrane, and the oxidation effect reduced the electric field threshold of membrane electroporation. Our simulation could provide theoretical support for the plasma-induced apoptosis of cancer cells at the microscopic level, provide mechanistic guidance for the practical application of plasma-induced cancer therapy, and promote the development of CAP in the field of cancer therapy.

[Decreased expression of CatSper1 in the sperm of varicocele rats and protective effect of L-carnitine].

OBJECTIVE: To investigate the expression of the sperm-specific cation channel (CatSper1) in the epididymal sperm of varicocele (VC) rats and the effect of L-carnitine (LC) on the CatSper1 level. METHODS: Seventy male rats were equally randomized into groups A (normal control), B (VC model control), C (VC treated with normal saline), D (VC treated with low-dose LC), E (VC treated with medium-dose LC), F (VC treated with high-dose LC), and G (VC treated by prolonged medication of high-dose LC). The VC model was established by partial ligation of the left renal vein. At 12 weeks after modeling, the model rats in group C were treated intragastrically with normal saline at 1 ml/kg/d, those in groups D, E and F with LC at 0.05, 0.1 and 0.2 g/kg/d respectively, all for 5 consecutive weeks, and those in group G with LC at 0.2 g/kg/d for 7 successive weeks. Then, all the animals were sacrificed and their epididymides harvested for obtainment of the semen parameters by computer-assisted semen analysis (CASA) and determination of the mRNA and protein expressions of CatSper1 in the sperm by RT-PCR and Western blot. RESULTS: Compared with the rats in group A, those in group B showed significantly decreased percentage of grade a+b sperm (P < 0.01), sperm viability (P < 0.01), sperm concentration (P < 0.01) and expressions of CatSper1 mRNA (1.44 ± 0.67 vs 0.71 ± 0.38, P < 0.01) and protein (1.87 ± 0.67 vs 0.84 ± 0.42, P < 0.01). In comparison with the animals in group C, those in the four LC intervention groups exhibited a markedly increased percentage of grade a+b sperm, sperm viability and mRNA and protein expressions of CatSper1, even more remarkably in groups F and G (P < 0.01). No statistically significant difference, however, was observed in sperm concentration between group C and the LC intervention groups (P > 0.05), nor in the mRNA and protein expressions of CatSper1 between groups F and G. CONCLUSIONS: The expression of CatSper1 is decreased in the epididymal sperm of varicocele rats, and L-carnitine can increase the sperm viability, percentage of grade a+b sperm and CatSper1 expression of the rats.