Stomach engineering: region-specific characterization of the decellularized porcine stomach.

PURPOSE: Patients affected by microgastria, severe gastroesophageal reflux, or those who have undergone subtotal gastrectomy, have commonly described reporting dumping syndromes or other symptoms that seriously impair the quality of their life. Gastric tissue engineering may offer an alternative approach to treating these pathologies. Decellularization protocols have great potential to generate novel biomaterials for large gastric defect repair. There is an urgency to define more reliable protocols to foster clinical applications of tissue-engineered decellularized gastric grafts. METHODS: In this work, we investigated the biochemical and mechanical properties of decellularized porcine stomach tissue compared to its native counterpart. Histological and immunofluorescence analyses were performed to screen the quality of decellularized samples. Quantitative analysis was also performed to assess extracellular matrix composition. At last, we investigated the mechanical properties and cytocompatibility of the decellularized tissue compared to the native. RESULTS: The optimized decellularization protocol produced efficient cell removal, highlighted in the absence of native cellular nuclei. Decellularized scaffolds preserved collagen and elastin contents, with partial loss of sulfated glycosaminoglycans. Decellularized gastric tissue revealed increased elastic modulus and strain at break during mechanical tensile tests, while ultimate tensile strength was significantly reduced. HepG2 cells were seeded on the ECM, revealing matrix cytocompatibility and the ability to support cell proliferation. CONCLUSION: Our work reports the successful generation of acellular porcine gastric tissue able to support cell viability and proliferation of human cells.

The detail profile of cause of recurrences after laparoscopic percutaneous extraperitoneal closure (LPEC) in children: a systematic review.

PURPOSE: Laparoscopic repairs for children with inguinal hernia have been established with various technical modifications. Laparoscopic percutaneous extraperitoneal closure (LPEC) is one of the most recognized techniques. Although the rate of complications of LPEC is similar to conventional repairs, the major cause of recurrence is still incompletely understood. The purpose of this study is to evaluate detail profile of the cause of recurrence in children treated with LPEC. METHODS: A systematic literature search was performed using the combinations of the following terms "pediatric inguinal hernia", "LPEC", "complication", and "recurrence" for studies published between 2002 and 2020. The relevant cohorts of recurrence of LPEC in children were systematically searched for clinical outcomes. RESULTS: 35 studies met defined inclusion criteria, reporting a total of 121 patients who had recurrence after LPEC. The mean age at primary operations was 46.7 ± 52.0 months. The gender proportions were 63.9% (male) and 36.1% (female). The rate of treatment side was 44.5% (right), 37.0% (left) and 18.5% (bilateral). The hernia sac was closed with absorbable suture materials (5.3%) and non-absorbable (94.7%). The recurrence occurred in 6.9 ± 8.5 months postoperatively. Operative findings of reoperation were loosening of the knot of internal rings (61.1%), low ligation of the inguinal canal (16.7%), and skipping (22.2%). CONCLUSIONS: This study suggests that male infants have a higher risk of recurrence after LPEC, and the majority of recurrences can occur in a year postoperatively. It is important to confirm carefully that the suture is tight and high without skipping.

Forty-Year Experience Alleviating Postoperative Hirschsprung-Associated Enterocolitis by Complete Full-Thickness Posterior Rectal Cuff Excision. The Anorectal Line Eliminates Problematic Anastomoses.

Introduction: A modified pull-through (PT) distinguished by complete full-thickness removal of the posterior rectal cuff, initially developed as an open procedure in 1980, has been performed with laparoscopic assistance since 1997. Postoperative bowel dysfunction improved when the anatomic landmark for PT surgery was revised from the dentate line (DL) to the anorectal (or Herrmann's) line (ARL) in 2007. A 40-year (1980-2019) review of 153 consecutive rectal/rectosigmoid type Hirschsprung's disease (HD) patients is presented. Methods: Data for postoperative bowel dysfunction and Hirschsprung-associated enterocolitis (HAEC) classified according to the American Pediatric Surgical Association (APSA) scale were obtained retrospectively. Results: PT was open (n = 43) and laparoscopic (n = 110). Dissection was DL (n = 57) and ARL (n = 96). Over 40 years, 5/153 patients (3.3%) had postoperative obstructive symptoms (POS), and 10/153 patients (6.5%) had 13 episodes of postoperative HAEC; APSA grades were: I (n = 4); II (n = 8); and III: (n = 1) presenting with explosive diarrhea (10/13; 76.9%), fever (10/13; 76.9%), abdominal distension (9/13; 69.2%), or bloody stools/shock (1/13 with grade III; 7.7%). The grade III case had histologically-proven transitional zone PT. Postoperative HAEC developed in 3/5 (60.0%) POS+ patients and 7/148 (4.7%) POS- patients (P = .002). Symptom duration and treatment were not correlated with APSA grades. Conclusions: Complete full-thickness posterior rectal cuff excision and using the ARL reduced postoperative HAEC significantly in this series. Despite being anatomically distinct, the DL is inadequate as a precise landmark for PT surgery because it lacks functional relevance. The APSA scale could benefit from timely review to improve its clinical and prognostic value.

Upper Critical Solution Temperature Behavior of pH-Responsive Amphoteric Statistical Copolymers in Aqueous Solutions.

Amphoteric statistical equivalent copolymers (P(2VP/NaSS) n ) composed of 2-vinylpyridine (2VP) and anionic sodium p-styrenesulfonate (NaSS) were prepared via reversible addition-fragmentation chain transfer polymerization. The degrees of polymerization (n) were 19 and 95. The monomer reactivity ratio, time conversion profile, and 1H nuclear magnetic resonance diffusion-ordered spectra suggested that the copolymerization of 2VP and NaSS provided statistical or near to random copolymers. P(2VP/NaSS) n exhibited an upper critical solution temperature (UCST) in acidic aqueous solutions on the basis of the charge interactions between the protonated cationic 2VP and anionic NaSS units. With an increase in pH value, the interaction was weakened because of the deprotonation of the 2VP units, thus reducing the UCST. At high [NaCl], the electrostatic interactions among the polymers were weakened because of the screening effect, and again, the UCST was reduced. With an increase in polymer concentration, the intra- and interpolymer interactions increased because of some entanglement, and the UCST consequently increased. Electrostatic interactions among the polymer chains with high molecular weight occurred easier than those among the low-molecular-weight polymer chains, which increased the UCST. The UCST also increased when deuterium oxide was used instead of hydrogen oxide, which was due to the isotopic effect. Hence, the UCST of P(2VP/NaSS) n can be adjusted according to the desired application.

Bone mineral density is increased in the cadmium-induced omphalocele chick model by using three-dimensional micro-computed tomography.

PURPOSE: The cadmium (Cd) chick model has been described as a reliable model of omphalocele. Skeletal anomalies, including lumber lordosis, can be seen in the Cd chick model, as well as in the human omphalocele. Bone deformations, such as lordosis, are associated with high bone mineral density (BMD). Recently, three-dimensional microcomputed tomography (3DMCT) has been used to investigate skeletal development in small animal embryos. We used 3DMCT to test the hypothesis that the BMD is increased in the Cd-induced omphalocele chick model. METHODS: After a 60-h incubation, chicks were exposed to either chick saline or Cd in ovo. Chick embryos were harvested at embryonic day 16.5 (E16.5) and were divided into control (n = 8) and Cd (n = 9). Chicks were then scanned by 3DMCT. The body volume, bone volume, bone/body volume ratio, bone mineral quantity and BMD were analysed statistically (significance was accepted at p < 0.05). RESULTS: Bone mineral density (mg/cm3) was significantly increased in the Cd group compared to control group (235.3 ± 11.7 vs 223.4 ± 4.6, p < 0.05), whereas there was no significant difference in the bone/body volume ratio between the Cd group and the control group (0.7 ± 0.1 vs 0.6 ± 0.0). The body volume (cm3) (0.3 ± 0.2 vs 0.3 ± 0.1), bone volume (cm3) (0.2 ± 0.2 vs 0.2 ± 0.1), and bone mineral quantity (mg) (51.3 ± 41.6 vs 41.5 ± 16.5) were not significantly different between the two groups. CONCLUSIONS: Increased BMD may be associated with lordosis of the vertebral column in the Cd-induced omphalocele chick model, stimulating osteogenesis by activating the canonical Wnt signalling pathway.

Upper Critical Solution Temperature (UCST) Behavior of Polystyrene-Based Polyampholytes in Aqueous Solution.

Strong polyampholytes comprising cationic vinylbenzyl trimethylammonium chloride (VBTAC) bearing a pendant quaternary ammonium group and anionic sodium p-styrenesulfonate (NaSS) bearing a pendant sulfonate group were prepared via reversible addition-fragmentation chain-transfer polymerization. The resultant polymers are labelled P(VBTAC/NaSS)n, where n indicates the degree of polymerization (n = 20 or 97). The percentage VBTAC content in P(VBTAC/NaSS)n is always about 50 mol%, as revealed by ¹H NMR measurements, meaning that P(VBTAC/NaSS)n is a close to stoichiometrically charge-neutralized polymer. Although P(VBTAC/NaSS)n cannot dissolve in pure water at room temperature, the addition of NaCl or heating solubilizes the polymers. Furthermore, P(VBTAC/NaSS)n exhibits upper critical solution temperature (UCST) behavior in aqueous NaCl solutions. The UCST is shifted to higher temperatures by increasing the polymer concentration and molecular weight, and by decreasing the NaCl concentration. The UCST behavior was measured ranging the polymer concentrations from 0.5 to 5.0 g/L.

Light Emitting Diodes based Photoacoustic Imaging and Potential Clinical Applications.

Using low cost and small size light emitting diodes (LED) as the alternative illumination source for photoacoustic (PA) imaging has many advantages, and can largely benefit the clinical translation of the emerging PA imaging technology. Here, we present our development of LED-based PA imaging integrated with B-mode ultrasound. To overcome the challenge of achieving sufficient signal-to-noise ratio by the LED light that is orders of magnitude weaker than lasers, extensive signal averaging over hundreds of pulses is performed. Facilitated by the fast response of the LED and the high-speed driving as well as the high pulse repetition rate up to 16 kHz, B-mode PA images superimposed on gray-scale ultrasound of a biological sample can be achieved in real-time with frame rate up to 500 Hz. The LED-based PA imaging could be a promising tool for several clinical applications, such as assessment of peripheral microvascular function and dynamic changes, diagnosis of inflammatory arthritis, and detection of head and neck cancer.

Handheld Real-Time LED-Based Photoacoustic and Ultrasound Imaging System for Accurate Visualization of Clinical Metal Needles and Superficial Vasculature to Guide Minimally Invasive Procedures.

Ultrasound imaging is widely used to guide minimally invasive procedures, but the visualization of the invasive medical device and the procedure’s target is often challenging. Photoacoustic imaging has shown great promise for guiding minimally invasive procedures, but clinical translation of this technology has often been limited by bulky and expensive excitation sources. In this work, we demonstrate the feasibility of guiding minimally invasive procedures using a dual-mode photoacoustic and ultrasound imaging system with excitation from compact arrays of light-emitting diodes (LEDs) at 850 nm. Three validation experiments were performed. First, clinical metal needles inserted into biological tissue were imaged. Second, the imaging depth of the system was characterized using a blood-vessel-mimicking phantom. Third, the superficial vasculature in human volunteers was imaged. It was found that photoacoustic imaging enabled needle visualization with signal-to-noise ratios that were 1.2 to 2.2 times higher than those obtained with ultrasound imaging, over insertion angles of 26 to 51 degrees. With the blood vessel mimicking phantom, the maximum imaging depth was 38 mm. The superficial vasculature of a human middle finger and a human wrist were clearly visualized in real-time. We conclude that the LED-based system is promising for guiding minimally invasive procedures with peripheral tissue targets.