Hybrid Electrospun Polycaprolactone Mats Consisting of Nanofibers and Microbeads for Extended Release of Dexamethasone.

PURPOSE: We designed electrospun polycaprolactone mats consisting of nanofibers and microbeads for extended delivery of dexamethasone. METHODS: Thin flexible dexamethasone loaded polycaprolactone mats were prepared by electrospinning. The solvents, polymer loading, voltage and tip-to-collector distance were varied to explore the effects on microstructure of the mats. The microstructure was determined by scanning electron microscope imaging; drug transport was measured and modeled, and X-ray diffraction was used to gauge the crystallinity. Drug transport and X-ray diffraction studies were also conducted with a spin cast film for comparison. RESULTS: Thin mats, about 10 µm in thickness, were prepared by electrospinning. By controlling the voltage and tip-to-collector distance, we achieved a hybrid structure comprising of nanorods (nanofibers) and microbeads. The release profiles were fitted to the diffusion equation to obtain the diffusivities in the spheres and the rods. The diffusivity in the electrospun nanofibers was significantly lower compared to the casted films due to increased crystallinity, which was estimated from X-ray diffraction analysis. The electrospun hybrid mats sustained drug release for the desired duration of a month, in spite of the small thickness of about 10 µm. By comparison, a ten-fold thicker cast film sustains release for about the same duration suggesting about 100-fold decrease in diffusivity in the electrospun mats due to increased crystallinity. CONCLUSIONS: Electrospun polycaprolactone mats are optimal for achieving long release durations due to increased crystallinity. Designing a hybrid structure by controlling the electrospinning parameters can be a useful approach to increase the release durations.

Tattooing or Metallic Clip Placement? A Review of the Outcome Surrounding Preoperative Localization Methods in Minimally Invasive Anterior Resection Performed at a Single Center.

BACKGROUND: For minimally invasive colorectal surgery, preoperative localization is a typical procedure. We here aimed to analyze compared 2 different localization methods in terms of short-term outcomes, like the operative outcome and postoperative complication rates based on real-world data. MATERIALS AND METHODS: This was a retrospective analysis study conducted at a medical center. We enrolled patients who were presented with colonic tumor between January 1, 2016, and December 31, 2019, and they had undergone laparoscopic anterior resection in a single institution. Data included patient characteristics, operative outcome, length of hospital stay, and postoperative complications. RESULTS: The preoperative localization group had a better resection margin (4 vs. 3 cm; P<0.001) and fewer procedures of intraoperative colonoscopy (4.67% vs. 18.22%; P=0.002). Lymph node harvest occurred more in patients with endoscopic tattooing procedures than with metallic clip procedures (25 vs. 20; P=0.031). No significant difference was found regarding postoperative complications and the length of hospital stay. CONCLUSIONS: Preoperative localization in a laparoscopic anterior resection led to better surgical planning and resection margin. The metallic clip placement was helpful in the preoperative localization and setting. The endoscopic tattooing method had a larger lymph node harvest and with fewer intraoperative colonoscopy.

Low prevalence of RET rearrangements (RET/PTC1, RET/PTC2, RET/PTC3, and ELKS-RET) in sporadic papillary thyroid carcinomas in Taiwan Chinese.

Somatic rearrangement of the tyrosine kinase receptor RET is restricted to papillary thyroid carcinoma (PTC). The prevalence of RET/PTC1, RET/PTC2, and RET/PTC3 has been found to vary between 0% and 20% in most series of sporadic (nonradiation-induced) PTCs analyzed by type-specific reverse transcription-polymerase chain reaction (RT-PCR) alone. However, high prevalence reported from Taiwan (6 out of 11, 55%) indicates RET rearrangement is an important genetic lesion underlying the development of PTC in Taiwan. Because the high prevalence of RET rearrangements in Chinese patients was particularly striking, we were prompted to reexamine chimeric transcripts of RET/PTC1, RET/PTC2, and RET/PTC3 using the same experimental designs in a larger number of cases in the same population. RT-PCR was performed to amplify fusion products of RET/PTC1, RET/PTC2, RET/PTC3, and ELKS-RET from frozen tissue of 105 sporadic PTCs. RT-PCR was also performed with two different primer sets for RET/PTC1, RET/PTC2, and RET/PTC3 followed by Southern hybridization in the first 62 tumors. In our study, RET/PTC1, RET/PTC2, and RET/PTC3 oncogenes were found in only 7 of 105 (7%) sporadic PTCs. Of these tumors, 3 involved RET/PTC1 and 4 involved RET/PTC3. No RET/PTC2 rearrangements were observed. In the first 62 tumor samples, another two different primer sets for each rearrangement also gave concordant results. Furthermore, application of Southern hybridization in these 62 PTCs did not identify additional tumor harboring RET chimeric transcripts. We identified one tumor as having an ELKS-RET rearrangement (1 of 105, 1%). In conclusion, we detected RET rearrangements in 8 of 105 (8%) sporadic PTCs in Taiwan, a much lower prevalence than previously reported for this population but comparable to those reported in other nations using similar methodology. RET chimeric oncogenes only account for a small fraction of PTCs in Taiwan.