Extensional Rheology of Poly(vinylidene fluoride)/N,N-dimethylformamide Solutions.

Typical extension flow occurs in electrospinning process of Poly(vinylidene fluoride) (PVDF) solutions such that researchers focus on extensional rheological behaviors of PVDF solutions. The extensional viscosity of PVDF solutions is measured to know the fluidic deformation in extension flows. The solutions are prepared by dissolving PVDF powder into N,N-dimethylformamide (DMF) solvent. A homemade extensional viscometric device is used to produce uniaxial extension flows and the feasibility of the viscometric device is verified by applying the glycerol as a test fluid. Experimental results show that PVDF/DMF solutions are extension shinning as well as shear shinning. The Trouton ratio of thinning PVDF/DMF solution is close to three at very low strain rate and then reaches a peak value until it drops to a small value at high strain rate. Furthermore, an exponential model may be used to fit the measured values of uniaxial extensional viscosity at various extension rates, while traditional power-law model is applicable to steady shear viscosity. For 10~14% PVDF/DMF solution, the zero-extension viscosity by fitting reaches 31.88~157.53 Pa·s and the peak Trouton ratio is 4.17~5.16 at applied extension rate of less than 34 s-1. Characteristic relaxation time is λ~100 ms and corresponding critical extension rate is ε˙c~5 s-1. The extensional viscosity of very dilute PVDF/DMF solution at very high extension rate is beyond the limit of our homemade extensional viscometric device. This case needs a higher sensitive tensile gauge and a higher-accelerated motion mechanism for test.

Gunsight sutures significantly reduce surgical-site infection after ileostomy reversal compared with linear sutures.

BACKGROUND: Surgical-site infection (SSI) was one of the most common post-operative morbidities of ileostomy reversal. Although several skin-closure procedures had been developed to reduce the rate of SSI, the optimal procedure remains unclear. In this study, we compared the effect of two surgical techniques for wound closure following ileostomy reversal: gunsight suture (GS) and linear suture (LS). METHODS: A total of 233 patients who underwent loop ileostomy at the Sixth Affiliated Hospital of Sun Yat-sen University between January 2015 and December 2017 were enrolled into our study. These patients were divided into two groups: the LS group and the GS group. We compared the clinical characteristics between the two groups and analyzed the data using IBM SPSS to identify risk factors for SSI. RESULTS: Both groups successfully underwent surgery. The rate of SSI was significantly lower in the GS group (n = 2, 0.02%) than in the LS group (n = 16, 12.00%, P = 0.007). The length of hospital stay after the operation in the GS group was significantly shorter than that in the LS group (8.1 ± 3.2 vs 10.8 ± 5.4 days, P < 0.001). Multivariate analysis showed that GS was an independent protective risk factor for SSI (odds ratio = 0.212, P = 0.048). CONCLUSIONS: Compared with the LS technique, the GS technique can significantly decrease the rate of SSI and shorten the length of hospital stay after surgery. The GS technique may be recommended for wound closure following ileostomy reversal.

Highly Stretchable, Adhesive, Biocompatible, and Antibacterial Hydrogel Dressings for Wound Healing.

Treatment of wounds in special areas is challenging due to inevitable movements and difficult fixation. Common cotton gauze suffers from incomplete joint surface coverage, confinement of joint movement, lack of antibacterial function, and frequent replacements. Hydrogels have been considered as good candidates for wound dressing because of their good flexibility and biocompatibility. Nevertheless, the adhesive, mechanical, and antibacterial properties of conventional hydrogels are not satisfactory. Herein, cationic polyelectrolyte brushes grafted from bacterial cellulose (BC) nanofibers are introduced into polydopamine/polyacrylamide hydrogels. The 1D polymer brushes have rigid BC backbones to enhance mechanical property of hydrogels, realizing high tensile strength (21-51 kPa), large tensile strain (899-1047%), and ideal compressive property. Positively charged quaternary ammonium groups of tethered polymer brushes provide long-lasting antibacterial property to hydrogels and promote crawling and proliferation of negatively charged epidermis cells. Moreover, the hydrogels are rich in catechol groups and capable of adhering to various surfaces, meeting adhesive demand of large movement for special areas. With the above merits, the hydrogels demonstrate less inflammatory response and faster healing speed for in vivo wound healing on rats. Therefore, the multifunctional hydrogels show stable covering, little displacement, long-lasting antibacteria, and fast wound healing, demonstrating promise in wound dressing.

Nomogram for Predicting Anastomotic Leakage after Rectal Cancer Surgery in Elderly Patients with Dysfunctional Stomata.

PURPOSE: Anastomotic leakage after rectal cancer surgery in elderly patients is a critical challenge. Many risk factors have been found and many interventions tried, but anastomotic leakage in elderly patients remains difficult to deal with. This study aimed to create a nomogram for predicting anastomotic leakage after rectal surgery in elderly rectal cancer patients with dysfunctional stomata. METHODS: We collected data from 326 consecutive elderly patients with dysfunctional stomata after rectal cancer surgery at the Sixth Affiliated Hospital, Sun Yat-Sen University from January 2014 to December 2019. Risk factors of anastomotic leakage were identified with multivariate logistic regression and used to create a nomogram. Predictive performance was evaluated by the area under the receiver-operating characteristic (ROC) curve. RESULTS: American Society of Anesthesiologists score ≥3, male sex, and neoadjuvant radiotherapy were identified as significantly associated factors that could be combined for accurate prediction of anastomotic leakage on multivariate logistic regression and development of a nomogram.The area under the ROC curve for this model was 0.645. The C-index value for this model was 0.645, indicating moderate predictive ability of the risk of anastomotic leakage. CONCLUSION: The nomogram showed good ability to predict anastomotic leakage in elderly patients with rectal cancer after surgery, and might be helpful in providing a reference point for selection of surgical procedures and perioperative treatment.

Core-Shell Poly(l-lactic acid)-Hyaluronic Acid Nanofibers for Cell Culture and Pelvic Ligament Tissue Engineering.

Pelvic organ prolapse (POP) has become one of the most common serious diseases affecting parous women. Weakening of pelvic ligaments plays an essential role in the pathophysiology of POP. Currently, synthetic materials are widely applied for pelvic reconstructive surgery. However, synthetic nondegradable meshes for POP therapy cannot meet the clinical requirements due to its poor biocompatibility. Herein, we fabricated electrospun core-shell nanofibers of poly(l-lactic acid)-hyaluronic acid (PLLA/HA). After that, we combined them with mouse bone marrow-derived mesenchymal stem cells (mBMSCs) to assess the cellular response and pelvic ligament tissue engineering in vitro. The cellular responses on the composite nanofibers showed that the core-shell structure nanofibers displayed with excellent biocompatibility and enhanced cellular activity without cytotoxicity. Moreover, compared with PLLA nanofibers seeded with mBMSCs, PLLA/HA nanofibers exhibited more cellular function, as revealed by the quantitative real-time polymerase chain reaction (RT-qPCR) for pelvic ligament-related gene markers including Col1a1, Col1a3 and Tnc. These features suggested that this novel core-shell nanofiber is promising in stem cell-based tissue engineering for pelvic reconstruction.

Transsacrococcygeal approach in rectal gastrointestinal stromal tumour resection: 10-year experience at a single centre.

BACKGROUND: The transsacrococcygeal (TSC) approach in rectal gastrointestinal stromal tumour (GIST) resection is clinically challenging and controversial, and we evaluated its value in the present study. METHODS: We enrolled patients who underwent rectal GIST resection by the TSC approach during 2008-2018. The clinicopathological index, surgical outcome, and prognosis were analysed. Prognostic information was obtained from medical records and follow-up data. Anal function was evaluated by the low anterior resection syndrome (LARS) score. RESULTS: Among 88 rectal GIST patients over the 10-year study period, 17 who underwent the TSC approach were analysed. The median age was 55 (range, 26-73) years. In total, 15 patients received preoperative imatinib neoadjuvant therapy for 232 (30-690) days. The tumours were exogenous in 14 patients and intramural in 3 patients. The mean initial tumour size and preoperative tumour size were 6.4±2.2 and 4.2±1.7 cm, respectively. The operative time and blood loss were 130.2±47.4 min and 44.6±36.0 mL, respectively. Of the 17 patients 7 had postoperative complications (within 30 days postoperatively), and the complications of 5 patients were cured by conservative treatment. Only 1 patient was lost to follow-up, and the others had a good oncological prognosis at recent follow-up evaluations. All patients had LARS scores ≤9 points at 1 year after the operation. CONCLUSIONS: The TSC approach can result in a good oncological prognosis, usually does not affect anal function, and is particularly suitable for exogenous middle and low rectal GISTs. However, it might cause some controlled complications. Hence, careful patient selection is necessary for this operation.

A nomogram to predict the incidence of permanent stoma in elderly patients with rectal cancer.

BACKGROUND: Creation of a temporary diverting stoma during rectal cancer surgery is used widely to prevent undesirable outcomes related to anastomotic leakage (AL). The transition from temporary stoma (TS) to permanent stoma (PS) is a frequent outcome. Elderly patients may have a greater probability of PS. We aimed to identify risk factors of PS and developed a nomogram to predict the rate of PS for elderly patients. METHODS: We enrolled elderly patients (≥70 years) who underwent rectal cancer surgery with a TS between January 2014 and December 2017 at our hospital. We divided patients into two groups: a TS group and a PS group. We then identified the risk factors for PS and developed a nomogram to predict the possibility of PS. RESULTS: Of the 278 elderly patients who received a diverting stoma, 220 (79.14%) eventually underwent stoma reversal, and 58 (20.86%) had PS. The proportion of males in the PS group was significantly higher than that of the TS group (P=0.048). Univariate and multivariate analysis showed that American Society of Anesthesiologists (ASA) score (P<0.001), laparotomy (P=0.004), AL (P<0.001), and tumor recurrence (P<0.001) were significantly correlated with PS. These four factors were included to construct the nomogram. The consistency index of the nomogram was 0.833 and the model yielded an area under the curve of 0.833. CONCLUSIONS: ASA score (≥3), laparotomy, AL, and tumor recurrence were independent risk factors for PS in elderly patients. Our nomogram exhibited moderate predictive ability.

Fabrication and Characterization of the Core-Shell Structure of Poly(3-Hydroxybutyrate-4-Hydroxybutyrate) Nanofiber Scaffolds.

Tissue engineering scaffolds with nanofibrous structures provide positive support for cell proliferation and differentiation in biomedical fields. These scaffolds are widely used for defective tissue repair and drug delivery. However, the degradation performance and mechanical properties of scaffolds are often unsatisfactory. Here, we successfully prepared a novel poly(3-hydroxybutyrate-4-hydroxybutyrate)/polypyrrole (P34HB-PPy) core-shell nanofiber structure scaffold with electrospinning and in situ surface polymerization technology. The obtained composite scaffold showed good mechanical properties, hydrophilicity, and thermal stability based on the universal material testing machine, contact angle measuring system, thermogravimetric analyzer, and other methods. The results of the in vitro bone marrow-derived mesenchymal stem cells (BMSCs) culture showed that the P34HB-PPy composite scaffold effectively mimicked the extracellular matrix (ECM) and exhibited good cell retention and proliferative capacity. More importantly, P34HB is a controllable degradable polyester material, and its degradation product 3-hydroxybutyric acid (3-HB) is an energy metabolite that can promote cell growth and proliferation. These results strongly support the application potential of P34HB-PPy composite scaffolds in biomedical fields, such as tissue engineering and soft tissue repair.

RNA-binding protein CELF1 enhances cell migration, invasion, and chemoresistance by targeting ETS2 in colorectal cancer.

Colorectal cancer (CRC) is often diagnosed at later stages after it has metastasized to other organs. The development of chemoresistance also contributes to a poor prognosis. Therefore, an increased understanding of the metastatic properties of CRC and chemoresistance could improve patient survival. CUGBP elav-like family member 1 (CELF1) is an RNA-binding protein, which is overexpressed in many human malignant tumors. However, the influence of CELF1 in CRC is unclear. V-ets erythroblastosis virus E26 oncogene homologue 2 (ETS2) is an evolutionarily conserved proto-oncogene known to be overexpressed in a variety of human cancers including CRC. In thespresent tudy, we investigated the association between CELF1 and ETS2 in CRC tumorigenesis and oxaliplatin (L-OHP) resistance. We found a positive correlation between the elevated expression of CELF1 and ETS2 in human CRC tissues. Overexpression of CELF1 increased CRC cell proliferation, migration, and invasion in vitro and in a xenograft tumor growth model in vivo, and induced resistance to L-OHP. In contrast, CELF1 knockdown improved the response of CRC cells to L-OHP. Overexpression of ETS2 increased the malignant behavior of CRC cells (growth, migration, and invasion) and L-OHP resistance in vitro. Moreover, L-OHP resistance induced by CELF1 overexpression was reversed by ETS2 knockdown. The results of luciferase reporter and ribonucleoprotein immunoprecipitation assays indicated that CELF1 up-regulates ETS2 by binding to its 3'-UTR. Taken together, our findings have identified that CELF1 regulates ETS2 in a mechanism that results in CRC tumorigenesis and L-OHP resistance, and CELF1 may be a promising target for overcoming chemoresistance in CRC.

Radical excision versus local resection for primary rectal gastrointestinal stromal tumors. Cohort Study.

BACKGROUND: Rectal gastrointestinal stromal tumor (GIST) is a rare digestive disease that originates in mesenchymal tissues and has malignant tendencies. At present, no standard treatment has been developed, and surgical approaches and the resection scope for rectal GISTs are controversial. METHODS: The clinical, surgical, pathological and prognosis data of patients with primary rectal GIST in our center from January 2008 to January 2019 were retrospectively collected. The patients were divided into the radical excision (RE) and local resection (LR) groups. RESULTS: A total of 537 GIST cases were collected, and 64 patients with primary rectal GIST were included in this study, including 25 cases in the RE group and 39 cases in the LR group. Tumor size (p = 0.013), distance from the anus (p = 0.038), National Institutes of Health (NIH) criteria (p = 0.001), preoperative adjuvant therapy (p = 0.016), postoperative adjuvant therapy (p = 0.028), blood loss (p = 0.048), operative time (p = 0.020) and the duration of hospitalization (p = 0.021) were statistically different between these 2 groups. The mean overall follow-up time was 46 months (range, 1-122 months). Disease recurrence was observed in 12 patients. No statistical differences were observed in 5-year disease-free survival (DFS) (93.3% vs 92.6%, p = 0.952) or overall survival (OS) (90.0% vs 91.6%, p = 0.832) between the RE group and the LR group. CONCLUSION: Our study showed that LR has a similar prognosis to that of RE with respect to DFS and OS. For appropriate cases, LR has the advantages of a short operative time, less bleeding, and a quick recovery. Especially when combined with neoadjuvant therapy, LR can also achieve better perioperative efficacy. Therefore, LR is an effective method for resection of rectal GISTs and warrants clinical endorsement.

Transanal versus nontransanal surgery for the treatment of primary rectal gastrointestinal stromal tumors: a 10-year experience in a high-volume center.

BACKGROUND: Rectal gastrointestinal stromal tumor (GIST) is a rare digestive disease that has a distinct malignant tendency compared to that of gastric-derived GIST. At present, there is still no standard, and the surgical approach to rectal GIST is controversial. METHODS: The clinicopathological data and prognosis of rectal GIST patients admitted to the Sixth Affiliated Hospital of Sun Yat-sen University from 1998.01.01 to 2018.12.31 were collected retrospectively. All cases were divided into either the transanal (TA) group or the nontransanal (NTA) group. RESULTS: A total of 537 GIST cases were treated in 10 years, including 82 rectal GIST cases (64 cases underwent surgical resection, including 29 cases in the TA group and 35 cases in the NTA group). Preoperative neoadjuvant therapy (P=0.003), postoperative adjuvant therapy (P=0.017), operative time (P=0.013), blood loss (P=0.038), anus-preserver (P=0.048), 30-day complication rate (P=0.000), time to flatus (P=0.036), hospital stays (P=0.011), distance from the anus (P=0.047), tumor size (P=0.002), mitotic count (P=0.035) and National Institutes of Health (NIH) criteria (P=0.000) were significantly different between these two groups (all P<0.05). The median follow-up time was 41 (range, 1-122) months. Twelve patients had recurrence and metastasis, and 4 patients died. The 5-year disease-free survival (DFS) and overall survival (OS) were 74.4% and 91.2%, respectively, in the whole group. There were no statistically significant differences between the TA group and the NTA group at 5-year DFS (81.3% vs. 79.0%, P=0.243) and OS (88.7% vs. 93.3%, P=0.308). CONCLUSIONS: In the treatment of rectal GIST, TA resection has a minimally invasive effect, less postoperative complications, high anal sphincter preservation rate, and R0 resection rate and a better prognosis. How to improve the proportion of neoadjuvant therapy and choose the appropriate cases for TA surgery is still a challenge.

[Hundred years development and future prospect of the material science for hernia].

Inguinal hernia is a defect disease in the abdominal wall. Surgeons have tried various ways to repair the defect for more than 100 years. The traditional herniorrhaphy destroys the normal anatomical structure, and the recurrence rate is quite high. After that, surgeons began to repair the defects with prostheses, from the initial use of rough metal materials such as silver, tantalum, stainless steel, to nylon, fiberglass, silicone rubber and other non-metallic materials, and also from artificial synthetic polymer non-absorbable materials such as polypropylene, polyester, ePTFE, to synthetic absorbable materials such as polyglycolic acid and the acellular extracellular matrix derived from biological meshes. However, these prostheses still can not meet the diverse needs of patients. Thus, multifunctional composite prostheses consisting of two or more materials were born, and various types of composite prostheses, stem cell coating meshes, 3D meshes, microstructure meshes were developed. The repair method evolved from traditional hernia repair to tension-free hernia repair and laparoscopic hernia repair. Surgeons are dedicated to finding idealized meshes for the perfect repair of defects, while considering postoperative complications, patient's quality of life, long-term efficacy and other issues. In the face of a wide variety of repair materials, the choice of surgeons is blind, and there is no standard to determine which prostheses are suitable for patients. Therefore, we have combed the development of different types of prostheses, summarized the development process of hernia repair materials for the past 100 years, and put forward the prospects for future development of prostheses, in order to provide reference for the selection of prostheses.