Impact of Dwell Time of Retrievable IVC Filters on IVC Lumen Diameter: A Series of 36 Cases.

BACKGROUND: Inferior vena cava (IVC) filters are effective in preventing pulmonary embolism in patients at risk. This study aimed to investigate whether the dwell time of retrievable IVC filters have impact on IVC lumen diameter. METHODS: The clinical data of 36 patients treated with retrievable IVC filters from January 2016 to November 2018 were retrospectively collected. A total of 33 filters were successfully removed. At times of filter placement and removal, the IVC lumen diameter (at upper, middle, and lower levels of the filter), distance between the filter upper end and the right renal vein opening, and degree of filter tilt were measured. RESULTS: IVC filters were placed because of deep vein thrombosis in the lower limbs after fractures in 26 patients. The median dwell time of the IVC filters was 18 days. From the time of filter placement to that of removal, the IVC diameter decreased significantly at the middle (28.07 ± 5.92 vs. 25.73 ± 7.33 mm, P = 0.002) and lower levels (27.48 ± 4.73 vs. 26.36 ± 4.72 mm, P = 0.003) of the filters. No significant difference was noticed in the IVC diameter at the upper levels of the filters (27.78 ± 6.43 vs. 27.11 ± 6.63 mm, P = 0.082). Positive correlation was noticed between filter dwell time and IVC diameter changes at the upper (r = 0.381, P = 0.029) and middle (r = 0.555, P = 0.001) levels of the filters. No significant change was noticed in the distance from the filter upper end to the right renal vein opening and the degree of filter tilt. CONCLUSIONS: Retrievable IVC filters are associated with IVC stenosis. The severity of IVC stenosis is positively correlated with the dwell time of filters.

Codelivery of paclitaxel and small interfering RNA by octadecyl quaternized carboxymethyl chitosan-modified cationic liposome for combined cancer therapy.

Conventional therapeutic approaches for cancer are limited by cancer cell resistance, which has impeded their clinical applications. The main goal of this work was to investigate the combined antitumor effect of paclitaxel with small interfering RNA modified by cationic liposome formed from modified octadecyl quaternized carboxymethyl chitosan. The cationic liposome was composed of 3ß-[N-(N', N'-dimethylaminoethane)-carbamoyl]-cholesterol, dioleoylphosphatidylethanolamine, and octadecyl quaternized carboxymethyl chitosan. The cationic liposome properties were characterized by Fourier transform infrared spectroscopy, dynamic light scattering and zeta potential measurements, transmission electron microscopy, atomic force microscopy, and gel retardation assay. The cationic liposome exhibited good properties, such as a small particle size, a narrow particle size distribution, a good spherical shape, a smooth surface, and a good binding ability with small interfering RNA. Most importantly, when combined with paclitaxel and small interfering RNA, the composite cationic liposome induced a great enhancement in the antitumor activity, which showed a significantly higher in vitro cytotoxicity in Bcap-37 cells than liposomal paclitaxel or small interfering RNA alone. In conclusion, the results indicate that cationic liposome could be further developed as a codelivery system for chemotherapy drugs and therapeutic small interfering RNAs.

Preparation of Chitosan-Based Hemostatic Sponges by Supercritical Fluid Technology.

Using ammonium bicarbonate (AB) particles as a porogen, chitosan (CS)-based hemostatic porous sponges were prepared in supercritical carbon dioxide due to its low viscosity, small surface tension, and good compatibility with organic solvent. Fourier transform infrared spectroscopy (FTIR) spectra demonstrated that the chemical compositions of CS and poly-(methyl vinyl ether-co-maleic anhydride) (PVM/MA) were not altered during the phase inversion process. The morphology and structure of the sponge after the supercritical fluid (SCF) process were observed by scanning electron microscopy (SEM). The resulting hemostatic sponges showed a relatively high porosity (about 80%) with a controllable pore size ranging from 0.1 to 200 µm. The concentration of PVM/MA had no significant influence on the porosity of the sponges. Comparative experiments on biological assessment and hemostatic effect between the resulting sponges and Avitene® were also carried out. With the incorporation of PVM/MA into the CS-based sponges, the water absorption rate of the sponges increased significantly, and the CS-PVM/MA sponges showed a similar water absorption rate (about 90%) to that of Avitene®. The results of the whole blood clotting experiment and animal experiment also demonstrated that the clotting ability of the CS-PVM/MA sponges was similar to that of Avitene®. All these results elementarily verified that the sponges prepared in this study were suitable for hemostasis and demonstrated the feasibility of using SCF-assisted phase inversion technology to produce hemostatic porous sponges.