Bubble nucleation in spherical liquid cavity wrapped by elastic medium

According to classical nucleation theory, gas nuclei can generate and grow into a cavitation bubble when the liquid pressure exceeds a threshold. However, classical nucleation theory does not include boundary effects. An enclosed spherical liquid cavity surrounded by elastic medium is introduced to model the nucleation process in tissue. Based on the equilibrium pressure relationship of a quasi-static process, the expressions of the threshold and the modified nucleation rate are derived by considering the tissue elasticity. It is shown that the constraint plays an important role in the nucleation process. There is a positive correlation between nucleation threshold pressure and constraint, which can be enhanced by an increasing tissue elasticity and reducing the size of the cavity. Meanwhile, temperature is found to be a key parameter of nucleation process, and cavitation is more likely to occur in confined liquids at temperature T > 100℃. In contrast, less influences are induced by these factors, such as bulk modulus, liquid cavity size, and acoustic frequency. Although these theoretical predictions of the thresholds have been demonstrated by many previous researches, much lower thresholds can be obtained in liquids containing dissolved gases, e.g., the nucleation threshold is about-21 MPa in a liquid of 0.8-nm gas nuclei at room temperature. Moreover, when there is a gas nucleus of 20 nm, the theoretical threshold pressure might be less than1 MPa.

Saponin from Tupistra chinensis Bak Inhibits NF-κB Signaling in Sarcoma S-180 Cell Mouse Xenografts

This study examined the effect of saponins from Tupistra chinensis Bak （STCB） on the growth of sarcoma S-180 cells in vitro and in mouse xenografts as well as the underlying mechanisms. Cell proliferation was assessed by MTT assay. Cell cycle distribution was determined by flow cytometry. Sarcoma S-180 tumor-bearing mice were treated with different doses of STCB with 10 μg/mL 5-fluorouracil （5-Fu） as a positive control. The activity of nuclear factor （NF）-κB was detected by gel mobility shift assay. The mRNA level of NF-κB was determined by real-time quantitative RT-PCR. The results showed that in vitro STCB inhibited the growth of S-180 cells in a concentration-dependent manner, which was accompanied by cell cycle arrest at S-phase. In vivo STCB significantly inhibited the growth of S-180 tumor mouse xenografts in a dose-dependent manner with apparent induction of cell apoptosis. Moreover, STCB inhibited the activity of NF-rd3 p65 and reduced the expression of NF-κB p65 mRNA in mouse xenografts. It was concluded that STCB inhibits the proliferation and cell cycle progression of S- 180 cells by suppressing NF-κB signaling in mouse xenografts. Our findings suggest STCB is a promising agent for the treatment of sarcoma.

Establishment and evaluation of Type 2 Diabetes Mellitus andits complications induced by low dose of multiple streptozotocin

Objective: To explore a simple, economical and feasible method for establishing type 2 diabetes mellitus and its complication model. Method: SD rats were randomly divided into two groups: normal group (15 rats) normal diet, model group (20 rats) with high glucose and high fat diet. After 2 weeks of feeding, model group was injected low dose(30mg/Kg) streptozotocin in the abdominal cavity, once a day for 6 days, normal group was injected with the same dose of citric acid buffer. Observe the changes of rat diet, body, hair, spirit, urine volume, and monitor weight, blood glucose. After 6 weeks, fast insulin, blood lipid, serum calcium, phosphorus and other biochemical indexes of rats, after HE staining observe morphologic variations changes of pancreas and kidney using microscope, and the changes of femoral bone in SD rats. Results: Compared with the normal group, the model group showed obvious symptoms, drink more, eat more, polyuria, emaciation, hyperglycemia, low calcium, low phosphorus, hyperlipidemia and other metabolic abnormalities, pancreatic atrophy, tissue fibrosis, glomerular area increased, basement membrane thickening, osteoporosis. Conclusion:High glucose and high fat diet combined with repeated intraperitoneal injecti on of low dose STZ can be successfully established the model of type 2 diabetes, and its high successful rate, low mortality rate, relatively simple, economical and feasible, has a certain significance of research on diabetes and its complications.