Efficacy and safety of endoscopic "calabash" ligation and resection for small gastric stromal tumors originating from the muscularis propria.

AIM: We compared endoscopic "calabash" ligation and resection (ECLR) and endoscopic submucosal excision (ESE) in treating endophytic gastric stromal tumors (GSTs) ≤15 mm in diameter originating from the muscularis propria. METHODS: We performed a retrospective study and included patients who visited our hospital for removal of small endophytic GSTs (diameter ≤ 15 mm) confirmed by postoperative pathological reports between February 2019 and December 2020. Patients were assigned to the study (received ECLR) or control (accepted ESE) groups, and their medical records were reviewed. Age, sex, GST size, resection outcomes, procedure measurements, lengths of hospital stays, medical expenses, intraoperative and postoperative complications, and follow-up outcomes were documented and compared between the two groups. Propensity score matching was used to avoid retrospective biases. RESULTS: A total of 277 patients were included in the analysis, with 135 in the study group and 142 in the control group. After propensity score matching, 119 cases in each group were finally included in the study. Compared to the control group, the study group had significantly shorter procedure durations and lengths of hospital stays, as well as reduced medical expenses. Compared to the control group, the study group also had significantly lower incidence rates of intraoperative stomach perforation, postoperative intraperitoneal infection, and postoperative electrocoagulation syndrome, as well as a lower intensity of postoperative pain. There were no significant differences in the other measurements between the two groups. CONCLUSION: ECLR is an effective and safe procedure for treating patients with endophytic GSTs ≤15 mm in diameter originating from the muscularis propria.

[Finite element analysis of optimal selection of cannulated threaded screw for the prevention of femoral neck shortening after internal fixation for femoral neck fracture].

OBJECTIVE: To propose the an optimal screw placement scheme to prevent femoral neck shortening, finite element analysis was used to evaluate the biomechanical outcome of different numbers formed by full threaded screws at different positions in the treatment of femoral neck fractures of Pauwels type Ⅱ. METHODS: Recruited for this study was a 55-year-old female volunteer with a weight of 70 kg and a height of 165 cm. CT scan data of her right femur was collected. The models of femoral of Pauwels typeⅡ and fully threaded screw(FTS) and partially threaded screw(PTS) were constructed in three-dimensional modeling software. All these screw placement schemes were divided into eight groups simulated the inverted triangular configuration:three PTSs, an anterosuperior FTS and two PTSs, a posterosuperior FTS and two PTSs, an inferior FTS and two PTSs, an anterosuperior PTS and two FTSs, a posterosuperior PTS and two FTSs, an inferior PTS and two FTSs and three FTSs. All fracture internal fixation models were processed in finite element analysis software. Parameters of postoperative femoral neck length, displacement distribution and peak displacement of screws and VonMises stress distribution and peak stress of screws, the proximal femur and fracture section were collected. RESULTS: The maximum VonMises stress of screws was 239.71, 213.44, 199.37, 230.82, 201.63, 215.72, 185.65 and 192.64 MPa, respectively, which was concentrated in the inferior screw near the fracture line. The maximum Von Mises stress of the proximal femur was 269.48, 241.62, 249.43, 269.69, 271.60, 346.64, 236.97 and 439.62 MPa, respectively, which was concentrated in the inferior medial area of subtrochanteric femur. The maximum Von Mises stress of fracture section was 149.12, 143.04, 140.47, 139.63, 139.81, 130.07, 117.77 and 57.89 MPa, respectively, which was concentrated around the partially threaded screw channel instead of the fully threaded screw channel. The maximum displacement of screws was 5.52, 5.43, 5.32, 5.17, 5.05, 5.13, 5.28 and 5.04 mm, respectively, which was along the axis of the femoral neck, and the displacement distribution was concentrated on the tip of the screw. The length of postoperative femoral neck length was 74.69, 74.72, 74.70, 74.70, 74.72, 74.70, 74.72 and 74.74 mm, respectively. CONCLUSION: The placement of one anterosuperior partially threaded screw and two fully threaded screws with an inverted triangular distribution can not only meet the sliding compression effect to promote femoral neck healing and ensure the stability of the proximal femur, but also reduce the degree of postoperative femoral neck shortening and reduce the incidence of hip joint dysfunction. This study provides a new optimal screw placement solution for the treatment of femoral neck fractures.

Correction to "Efficacy and safety of endoscopic resection in treatment of small gastric stromal tumors: A state-of-the-art review".

[This corrects the article on p. 462 in vol. 13, PMID: 34163567.].

Ideal nodal rings of one-dimensional photonic crystals in the visible region.

Three-dimensional (3D) artificial metacrystals host rich topological phases, such as Weyl points, nodal rings, and 3D photonic topological insulators. These topological states enable a wide range of applications, including 3D robust waveguides, one-way fiber, and negative refraction of the surface wave. However, these carefully designed metacrystals are usually very complex, hindering their extension to nanoscale photonic systems. Here, we theoretically proposed and experimentally realized an ideal nodal ring in the visible region using a simple 1D photonic crystal. The π-Berry phase around the ring is manifested by a 2π reflection phase's winding and the resultant drumhead surface states. By breaking the inversion symmetry, the nodal ring can be gapped and the π-Berry phase would diffuse into a toroidal-shaped Berry flux, resulting in photonic ridge states (the 3D extension of quantum valley Hall states). Our results provide a simple and feasible platform for exploring 3D topological physics and its potential applications in nanophotonics.

Efficacy and safety of endoscopic resection in treatment of small gastric stromal tumors: A state-of-the-art review.

Gastrointestinal stromal tumors can occur in any part of the gastrointestinal tract, but gastric stromal tumors (GSTs) are the most common. All GSTs have the potential to become malignant, and these can be divided into four different grades by risk from low to high: Very low risk, low risk, medium risk, and high risk. Current guidelines all recommend early complete excision of GSTs larger than 2 cm in diameter. However, it is not clear whether small GSTs (sGSTs, i.e., those smaller than 2 cm in diameter) should be treated as early as possible. The National Comprehensive Cancer Network recommends that endoscopic ultrasonography-guided (EUS-guided) fine-needle aspiration biopsy and imaging (computed tomography or magnetic-resonance imaging) be used to assess cancer risk for sGSTs detected by gastroscopy to determine treatment. When EUS indicates a higher risk of tumor, surgical resection is recommended. There are some questions on whether sGSTs also require early treatment. Many studies have shown that endoscopic treatment of GSTs with diameters of 2-5 cm is very effective. We here address whether endoscopic therapy is also suitable for sGSTs. In this paper, we try to explain three questions: (1) Does sGST require treatment? (2) Is digestive endoscopy a safe and effective means of treating sGST? and (3) When sGSTs are at different sites and depths, which endoscopic treatment method is more suitable?

Phase characterisation of metalenses.

Metalenses have emerged as a new optical element or system in recent years, showing superior performance and abundant applications. However, the phase distribution of a metalens has not been measured directly up to now, hindering further quantitative evaluation of its performance. We have developed an interferometric imaging phase measurement system to measure the phase distribution of a metalens by taking only one photo of the interference pattern. Based on the measured phase distribution, we analyse the negative chromatic aberration effect of monochromatic metalenses and propose a feature size of metalenses. Different sensitivities of the phase response to wavelength between the Pancharatnam-Berry phase-based metalens and propagation phase-reliant metalens are directly observed in the experiment. Furthermore, through phase distribution analysis, it is found that the distance between the measured metalens and the brightest spot of focusing will deviate from the focal length when the metalens has a low nominal numerical aperture, even though the metalens is ideal without any fabrication error. We also use the measured phase distribution to quantitatively characterise the imaging performance of the metalens. Our phase measurement system will help not only designers optimise the designs of metalenses but also fabricants distinguish defects to improve the fabrication process, which will pave the way for metalenses in industrial applications.

Effect of aluminum phosphate gel on prevention of early rebleeding after ligation of esophageal variceal hemorrhage.

BACKGROUND: Liver cirrhosis is the main cause of portal hypertension. The leading cause of death in patients with liver cirrhosis is its most common complication, esophageal variceal bleeding (EVB). Endoscopic variceal ligation (EVL) is recommended by many guidelines to treat EVB and prevent rebleeding; however, esophageal ulcers occur after treatment. Delayed healing of ulcers and unhealed ulcers lead to high rebleeding and mortality rates. Thus, the prevention of early postoperative rebleeding is of great significance in improving the quality of life and prognosis of patients. AIM: To evaluate the efficacy of aluminum phosphate gel (APG) plus a proton pump inhibitor (PPI) in the prevention of early rebleeding after EVL in patients with EVB. METHODS: The medical records of 792 patients who were diagnosed with EVB and in whom bleeding was successfully stopped by EVL at Shenzhen People's Hospital, Guangdong Province, China from January 2015 to December 2020 were collected. According to the study inclusion and exclusion criteria, 401 cases were included in a PPI-monotherapy group (PPI group), and 377 cases were included in a PPI and APG combination therapy (PPI + APG) group. We compared the incidence rates of early rebleeding and other complications within 6 wk after treatment between the two groups. The two-sample t-test, Wilcoxon rank-sum test, and chi-squared test were adopted for statistical analyses. RESULTS: No significant differences in age, sex, model for end-stage liver disease score, coagulation function, serum albumin level, or hemoglobin level were found between the two groups. The incidence of early rebleeding in the PPI + APG group (9/337; 2.39%) was significantly lower than that in the PPI group (30/401; 7.48%) (P = 0.001). Causes of early rebleeding in the PPI group were esophageal ulcer (3.99%, 16/401) and esophageal varices (3.49%, 14/401), while those in the PPI + APG group were also esophageal ulcers (5/377; 1.33%) and esophageal varices (4/377; 1.06%); such causes were significantly less frequent in the PPI + APG group than in the PPI group (P = 0.022 and 0.024, respectively). The early mortality rate within 6 wk in both groups was 0%, which was correlated with the timely rehospitalization of all patients with rebleeding and the conduct of emergency endoscopic therapy. The incidence of adverse events other than early bleeding in the PPI + APG group (28/377; 7.43%) was significantly lower than that in the PPI group (63/401; 15.71%) (P < 0.001). The incidence of chest pain in the PPI + APG group (9/377; 2.39%) was significantly lower than that in the PPI group (56/401; 13.97%) (P < 0.001). The incidence of constipation in the PPI + APG group (16/377; 4.24%) was significantly higher than that in the PPI group (3/401; 0.75%) (P = 0.002) but constipation was relieved after patients drank more water or took lactulose. In the PPI and PPI + APG groups, the incidence rates of spontaneous peritonitis within 6 wk after discharge were 0.50% (2/401) and 0.53% (2/377), respectively, and those of hepatic encephalopathy were 0.50% (2/401) and 0.27% (1/377), respectively, presenting no significant difference (P > 0.999). CONCLUSION: PPI + APG combination therapy significantly reduces the incidence of early rebleeding and chest pain in patients with EVB after EVL.