Gastric submucosa is inferior to the liver as transplant site for autologous islet transplantation in pancreatectomized diabetic Beagles.

Intraportal transplantation of islets is no longer considered to be an ideal procedure and finding the extrahepatic alternative site is becoming a subject of high priority. Herein, in this study, we would introduce our initial outcomes of using gastric submucosa (GS) and liver as sites of islet autotransplantation in pancreatectomized diabetic Beagles. Total pancreatectomy was performed in Beagles and then their own islets extracted from the excised pancreas were transplanted into GS (GS group, n=8) or intrahepatic via portal vein (PV group, n=5). Forty-eight hours post transplantation, graft containing tissue harvested from the recipients revealed the presence of insulin-positive cells. All recipients in GS group achieved euglycemia within 1 day, but returned to a diabetic state at 6 to 8 days post-transplantation (mean survival time, 7.16±0.69 days). However, all of the animals kept normoglycemic until 85 to 155 days post-transplantation in PV group (mean survival time, 120±28.58 days; P<0.01 vs. GS group). The results of intravenous glucose tolerance test (IVGTT) confirmed that the marked improvement in glycometabolism was obtained in intrahepatic islet autotransplantation. Thus, our findings indicate that the liver is still superior to the GS as the site of islet transplantation, at least in our islet autotransplant model in pancreatectomized diabetic Beagles.

Reprogrammed Stomach Tissue as a Renewable Source of Functional ß Cells for Blood Glucose Regulation.

The gastrointestinal (GI) epithelium is a highly regenerative tissue with the potential to provide a renewable source of insulin(+) cells after undergoing cellular reprogramming. Here, we show that cells of the antral stomach have a previously unappreciated propensity for conversion into functional insulin-secreting cells. Native antral endocrine cells share a surprising degree of transcriptional similarity with pancreatic ß cells, and expression of ß cell reprogramming factors in vivo converts antral cells efficiently into insulin(+) cells with close molecular and functional similarity to ß cells. Induced GI insulin(+) cells can suppress hyperglycemia in a diabetic mouse model for at least 6 months and regenerate rapidly after ablation. Reprogramming of antral stomach cells assembled into bioengineered mini-organs in vitro yielded transplantable units that also suppressed hyperglycemia in diabetic mice, highlighting the potential for development of engineered stomach tissues as a renewable source of functional ß cells for glycemic control.

[Investigation of simple and complex prelamination of vascularized flaps in experiment].

Prelamination, permitting improvement not esthetics only, but also function of the damaged region, to create necessary, by contents and configuration, vascularized complexes of tissues, is applied for effective treatment of complex defects in tissues. In experiment on laboratory animals for prelamination of vascularized flaps were applied separate and combined placement of mucosal and cartilaginous autotransplants. Results of the investigation witness possibility and efficacy of creation of content--component complexes of tissues, owing necessary characteristics for their further application in the clinic during performance of reconstructive interventions.

Assessment of a tissue-engineered gastric wall patch in a rat model.

Stenosis or deformity of the remaining stomach can occur after gastrectomy and result in stomach malfunction. The objective of this study is to demonstrate the feasibility of transplanting a tissue-engineered gastric wall patch in a rat model to alleviate the complications after resection of a large area of the gastric wall. Tissue-engineered gastric wall patches were created from gastric epithelial organoid units and biodegradable polymer scaffolds. In the first treatment group, gastric wall defects were created in recipient rats and covered with fresh tissue-engineered gastric wall patches (simultaneous transplantation). In the second treatment group, the tissue-engineered gastric wall patches were frozen for 12weeks, and then transplanted in recipient rats (metachronous transplantation). Tissue-engineered gastric wall patches were successfully used as a substitute of the resected native gastric wall in both simultaneous and metachronous transplantation groups. The defrosted wall patches showed almost the same cell viability as the fresh ones. Twenty-four weeks after transplantation, the defect in the gastric wall was well-covered with tissue-engineered gastric wall patch, and the repaired stomach showed no deformity macroscopically in both groups. Histology showed continuous mucosa and smooth muscle layers at the tissue-engineered stomach wall margin. The feasibility of transplanting a tissue-engineered patch to repair a defect in the native gastric wall has been successfully shown in a rat model, thereby taking one step closer toward the transplantation of an entire tissue-engineered stomach in the future.

The repair of a large duodenal defect by a pedicled gastric seromuscular flap.

PURPOSE: The aim was to evaluate the efficacy of a pedicled gastric seromuscular flap for the closure of a large duodenal defect. METHODS: A large defect of the second duodenal part was repaired by a gastric seromuscular flap. Of 35 rats, 9 rats were euthanized at 2 weeks, 12 rats at 2 months, and 14 rats at 4 months for the histopathological evaluation of the patch and normal duodenum (control) adjacent to the patch. RESULTS: All rats survived. The patch was completely covered by neomucosa in all of the 4-month rats, and in 8 of the 12 2-month rats. The villous height of the neomucosa was significantly higher in the 4-month rats in comparison to the other rats (P < 0.001). However, a normal duodenum had higher villi than in that of the patches (P < 0.001). The crypt density of the neomucosa was significantly increased in the 4-month rats in comparison to the 2-week and the 2-month rats (P < 0.001 and P < 0.05 group, respectively). The crypt density was higher in the controls than in the neomucosa covered patch of the 2-week and the 2-month rats (P < 0.001 and P < 0.05, respectively). The crypt depth of the neomucosa increased significantly in the 4-month rats and in the controls versus the 2-week rats (P < 0.05). CONCLUSION: The new mucosal barrier overlaying the patch appeared to be satisfactory. This technique, which has not been described previously, is likely to be useful for the repair of the large duodenal defect.

Morbidity and functional outcomes following gastro-omental free flap reconstruction of circumferential pharyngeal defects.

BACKGROUND: In patients with extensive soft tissue fibrosis requiring circumferential pharyngeal reconstruction following definitive radiotherapy and/or chemotherapy, we take advantage of abundant omental progenitor factors in the tubed gastro-omental free flap. This study reviews our experience with this flap. METHODS: Review of 11 patients (median follow-up, 2.8 years) undergoing total pharyngolaryngectomy following organ preservation protocols for recurrent squamous cell carcinoma (n = 9) and stricture (n = 2). RESULTS: Operative morbidity and mortality rates were 54% and 9%, respectively. One patient died following carotid rupture. Complications included: chyle leak (18%), pharyngocutaneous fistula (9%), and late stricture (27%). Ten patients (91%) achieved oral diet, and all 7 patients (100%) considered suitable for tracheoesophageal speech rehabilitation achieved functional speech. Seven patients remain alive without disease at a median of 41 months following surgery. CONCLUSIONS: The gastro-omental flap provides a viable option in high-risk patients undergoing circumferential pharyngeal reconstruction.

Sensory recovery of noninnervated free flap in oral and oropharyngeal reconstruction.

The sensory recovery of noninnervated free flaps used in oral and oropharyngeal reconstruction is analysed retrospectively to evaluate the degree of sensory recovery in different free flaps; and to assess the influence of various clinical and surgical factors on the recovery. A total of 40 patients who underwent oral and oropharyngeal reconstruction with noninnervated radial forearm (24), jejunal (10) or gastro-omental (6) free flaps were studied for at least 12 months postoperatively. The modalities examined were light touch, sharp prick, hot and cold temperature and static two-point discrimination. All the modalities showed statistically significant recovery in all flaps (p<0.05). The degree of sensory recovery for each modality is highest in the radial forearm followed by gastro-omental and lastly jejunal flaps. The differences between radial forearm and gastro-omental/jejunal flaps are statistically significant (p<0.05) except for light touch. The differences between the later two groups of flaps did not show statistical significance (p>0.05). Sensory recovery for all modalities in all flaps was not dependent on sex, age, smoking, flap size, postoperative radiotherapy or follow-up period (p>0.05).

Proton pump inhibitors relieve and prevent symptoms related to gastric acidity after esophagectomy.

BACKGROUND: Denervated stomach used as an esophageal substitute after esophagectomy often retains or spontaneously recovers acid production. The aims of the present study were to assess the relationship between esophageal acid exposure or gastric acidity and reflux-related symptoms after esophagectomy, and to assess the ability of proton pump inhibitors (PPIs) to relieve gastroesophageal reflux-related symptoms. METHODS: Forty-four patients underwent esophageal and gastric 24-h pH monitoring early after esophagectomy with gastric reconstruction. Initially, patients with both gastric acidity and reflux symptoms were treated with PPIs (Treatment group), then all patients with gastric acidity, whether symptomatic or not, were treated (Prevention group). Reflux-related symptoms were correlated with esophageal acid exposure and postoperative gastric acidity. Gastric acidity was then correlated with serum anti-Helicobacter pylori immunoglobulin G (IgG) titers and preoperative endoscopic findings RESULTS: Sixteen patients (36.4%) reporting reflux and showing gastric acid production were treated with PPIs, which provided relief to 13 (81.3%). Although symptoms did not correlate with the esophageal acid exposure, postoperative gastric acidity was significantly greater among patients who were symptomatic than among those who were not. Overall, acid production was lower in older patients (>64 years of age), although older patients who were H. pylori-negative and without chronic atrophic gastritis also showed high levels of gastric acidity. CONCLUSIONS: Proton pump inhibitors should be administered prophylactically early after esophagectomy to relieve and prevent reflux-related symptoms. Candidates for preventive therapy include those less than 64 years of age or older patients who are H. pylori-negative and without chronic atrophic gastritis.

Tumor in bladder reservoir after gastrocystoplasty.

PURPOSE: To our knowledge the risk of malignancy in patients with previous bladder augmentation with stomach is unknown. We report 3 cases of gastric adenocarcinoma and 1 of transitional cell carcinoma after augmentation cystoplasty with stomach with long-term followup. MATERIALS AND METHODS: Between August 1989 and August 2002, 119 patients underwent augmentation cystoplasty with stomach at our 2 institutions (University of Miami School of Medicine, and Seattle Children's Hospital and Regional Medical Center). Medical records, urodynamic studies, radiographic imaging and laboratory evaluations were reviewed retrospectively and cases of malignancy were analyzed in detail. RESULTS: Four male patients had carcinoma after augmentation gastrocystoplasty. Preoperative diagnosis was neurogenic bladder in 3 patients and posterior urethral valve in 1. Three patients had gastric adenocarcinoma, while the other had poorly differentiated transitional cell carcinoma. Each case progressed to malignancy more than 10 years after augmentation (11, 12, 14 and 14 years, respectively). CONCLUSIONS: Patients who undergo bladder augmentation with a gastric remnant are at increased risk for malignancy, probably similar to that in patients with enterocystoplasty. Therefore, they require close long-term followup. Patients should be followed annually with ultrasound, and cystoscopy should be performed annually starting 10 years after gastrocystoplasty unless they have abnormal ultrasound, hematuria or another cancer risk factor. Any suspicious lesions should be biopsied, especially at the gastrovesical anastomotic site.

Tracheoesophageal speech following laryngopharyngectomy and pharyngeal reconstruction.

Voice restoration following total laryngectomy and pharyngeal reconstruction is an achievable yet challenging reconstructive task. Because numerous methods exist for pharyngeal reconstruction in conjunction with total laryngectomy, a thorough knowledge of the tissues used for reconstruction is necessary. This knowledge allows for realistic expectations for patient success. Also, specific modifications in voice restoration may be necessary with individual reconstruction methods. This article reviews the methods for reconstruction and the available literature on voice restoration in reconstructed patients.

Bladder augmentation with an omental pedicled gastric seromuscular flap without the necessity of gastric resection.

Bladder augmentation using gastrointestinal segments requires gastric or intestinal resection. This has several risks. In a rat model, we aimed to test the efficacy of a new procedure in which a gastric seromuscular (GSM) flap is separated from the gastric mucosa without the necessity of gastric resection, and this GSM flap, based on an omentum pedicle, is transferred to the bladder. A GSM flap based on an omental leaf was dissected from the gastric mucosa and rotated 180 degrees counter-clockwise, after ligation of the vessels relating to the omentum, until the mid-duodenum. After urodynamic analysis for control levels of bladder capacity and pressure, the GSM flap was anastomosed to the bladder with a continuous suture. Because four rats died due to bladder calculi, only 21 of 25 rats were killed at 1 month (n = 10) and 4 months (n = 11) for histopathological and urodynamic evaluations of the augmented bladder. Bladder capacity increased significantly in the augmented bladders compared to preaugmentation (P < 0.001). There was no significant difference between end-filling pressures of the augmented bladders and preaugmentation. Histopathological findings demonstrated that the muscular surface of the flap was completely re-epithelialized in all rats. Squamous metaplasia was detected in 30% (3/10) of the 1 month group rats, and in 55% (6/11) of 4 month rats (P > 0.05). Gross calculi formation appeared in 20% (2/10) of the 1 month group rats, and in 34% (4/11) of 4 month rats (P > 0.05). Our data show that the use of the GSM flap in the bladder of a rat resulted in the complete re-epithelialization of the flap and sufficient bladder capacity. Despite significant complications such as death, metaplasia and calculi, this technique may be considered as an alternative experimental model to traditional full-thickness patching, which needs gastric or intestinal resection.

Reverse serosal demucosalized gastrocystoplasty.

A novel technique of augmentation cystoplasty is suggested. The patch which is advocated is less likely to cause electrolyte imbalance, is autologous and easily available. It will avoid all the gut-mucosa-related early and late postoperative complications.

Gastric penetration of amoxicillin in a human Helicobacter pylori-infected xenograft model.

The delivery of antibiotics into Helicobacter pylori-infected human stomachs is still poorly understood. Human embryonic gastric xenografts in nude mice have recently been proposed as a new model for the study of H. pylori infection. Using this model, we compared the penetration of amoxicillin, after intraperitoneal administration of a dose of 20 mg/kg of body weight, into the gastric mucosae of infected and uninfected xenografts. The concentrations of this drug in serum and superficial gastric mucosae were determined at 20 min and 1 and 3 h after injection. Ten mice with H. pylori-infected grafts (n = 5) or uninfected grafts (n = 5) were studied. Mucosal samples were obtained by cryomicrotomy. The concentrations in serum were similar to those obtained in the serum of humans after oral administration of 1 g of amoxicillin. The mean area under the tissue concentration-versus-time curve from 0 to 3 h obtained for mice with infected grafts was significantly higher than that obtained for the animals with uninfected grafts (P = 0.01). These results suggest that the penetration of amoxicillin into the superficial gastric mucosa may be substantially increased in the case of H. pylori infection. Thus, human xenografts in nude mice represent a new, well-standardized model for investigation of systemic delivery of drugs into H. pylori-infected gastric mucosa.

Augmentation cystoplasty using pedicled and de-epithelialized gastric patches in the mini-pig model.

PURPOSE: The most common methods of bladder augmentation are gastrocystoplasty and enterocystoplasty. Gastrocystoplasty is advantageous due to minimal mucous secretion and a well developed muscular wall as well as good urodynamic properties of the patch. However, the permanent contact of urine with the gastric mucosa is not free of complications. We report the urodynamic, macroscopic and histological outcomes of a pedicled de-epithelialized gastric patch incorporated in the bladder. We compared the results to those of our previous study, which sought to analyze these techniques of patch coverage using sigmoid patches. MATERIALS AND METHODS: We performed 20 augmentation cystoplasties in the mini-pig model using a pedicled de-epithelialized gastric patch and 5 techniques of patch coverage. RESULTS: Three months after surgery all bladders had an increase in volume except those in which the auto-augmentation technique was used. However, all gastric patches were smaller compared to preoperative size. Many had irregular fibrosed inner surfaces and histological evaluation revealed a fibrosed newly formed submucosal layer with a complete urothelial coverage in every patch. No gastric mucosal remnant was found. CONCLUSIONS: De-epithelialized gastrocystoplasty is an attractive procedure that can increase bladder capacity as well as provide a complete urothelial lining without mucosal remnants. However, the success of this procedure seems to be limited by increased morbidity and fibrotic changes, and decreased surface of the patch.

[Transplantation of pedicled gastric wall flaps to the intestines in Wistar rats].

The pedicled gastric wall flaps of Wistar rats were transplanted to their duodenum, jejunum and colon respectively. After the operation the rats were killed at the 3rd, 6th, 9th and 12th month respectively. Intestinal metaplasia (IM) was observed in all the gastric grafts transplanted to the intestines under photomicroscope, TEM and SEM. Alkaline phosphatase positive IM was seen in the gastric graft mucosa transplanted to the duodenum and jejunum. The results showed that the formation of IM of the gastric mucosa may be related to a change of the microenvironment around the tissues and that gastric mucosa may differentiate into intestinal mucosa by the increase of pH value.