RESUMEN
Limiting the spread of synthetic genetic information outside of the intended use is essential for applications where biocontainment is critical. In particular, biocontainment of engineered probiotics and plasmids that are excreted from the mammalian gastrointestinal tract is needed to prevent escape and acquisition of genetic material that could confer a selective advantage to microbial communities. Here, we built a simple and lightweight biocontainment system that post-translationally activates a site-specific DNA endonuclease to degrade DNA at 18°C and not at higher temperatures. We constructed an orthogonal set of temperature-sensitive meganucleases (TSMs) by inserting the yeast VMA1 L212P temperature-sensitive intein into the coding regions of LAGLIDADG homing endonucleases. We showed that the TSMs eliminated plasmids carrying the cognate TSM target site from laboratory strains of Escherichia coli at the permissive 18°C but not at higher restrictive temperatures. Plasmid elimination is dependent on both TSM endonuclease activity and intein splicing. TSMs eliminated plasmids from E. coli Nissle 1917 after passage through the mouse gut when fecal resuspensions were incubated at 18°C but not at 37°C. Collectively, our data demonstrates the potential of thermoregulated meganucleases as a means of restricting engineered plasmids and probiotics to the mammalian gut.
Asunto(s)
Inteínas , Proteínas de Saccharomyces cerevisiae , Animales , Ratones , Inteínas/genética , Escherichia coli/genética , Escherichia coli/metabolismo , Empalme de Proteína , ADN/metabolismo , Saccharomyces cerevisiae/genética , Plásmidos/genética , Mamíferos/genética , ATPasas de Translocación de Protón , Proteínas de Saccharomyces cerevisiae/genéticaRESUMEN
Background: Fibromuscular dysplasia is a non-inflammatory, non-atherosclerotic vascular disease that commonly affects renal and carotid arteries but involvement of virtually any vascular territory has been observed.Research Design/ Study sample: This is a case report of a ruptured left gastric artery aneurysm as the first presentation of fibromuscular dysplasia.Data collection: After written consent from the patient, relevant clinical notes and imaging were retrospectively reviewed and critically analysed.Purpose: This case reiterates the importance of considering fibromuscular dysplasia as an uncommon cause of visceral artery aneurysms. In addition, this case shows that the impact of visceral artery vasospasm on endovascular access should not be underestimated and subsequent attempts can be successful after a period of resuscitation.Results: After initial difficulty in endovascular treatment due to visceral vasospasm, the case was successfully managed with with staged open ligation and endovascular embolization after a period of resuscitation.Conclusions: FMD is an important differential diagnosis to consider in cases of visceral aneurysms.
Asunto(s)
Aneurisma Roto , Aneurisma , Displasia Fibromuscular , Aneurisma/diagnóstico por imagen , Aneurisma/etiología , Aneurisma/cirugía , Aneurisma Roto/diagnóstico por imagen , Aneurisma Roto/etiología , Aneurisma Roto/cirugía , Displasia Fibromuscular/complicaciones , Displasia Fibromuscular/diagnóstico por imagen , Displasia Fibromuscular/terapia , Artería Gástrica , Humanos , Estudios Retrospectivos , Resultado del TratamientoRESUMEN
BACKGROUND: There is currently limited data to reassure the technical efficacy, particularly in attaining clear margins, through a transgastric laparo-endoscopic approach to resecting tumours located near the gastroesophageal junction (GOJ) or the pylorus. METHODS: Single institution retrospective analysis of all cases from 1 April 2008 to 31 Dec 2019. RESULTS: Overall, 34 patients (38 tumours) underwent transgastric laparo-endoscopic resection. Of these, 27 (71.1%) and 5 (14.7%) cases were located close to the GOJ and pylorus respectively. Three (8.0%) cases were converted to conventional laparoscopic excision. No anatomical gastric resection was required. The mean (SD) operative time was 167.5 (64.2) minutes and reduced with increasing experience. The median (IQR) length-of-stay was 3.0 (3.0-4.5) days. Major post-operative complication (Clavian-Dindo ≥3) occurred in 1 (2.9%) patient, which required surgical control of staple line bleeding. The most common pathology was gastrointestinal stromal tumour (71.1%), followed by leiomyoma (10.5%), schwannoma (5.2%), dysplastic polyp (5.2%), and neuroendocrine tumour (2.6%). The mean (SD) tumour diameter was 3.9 (2.1) cm (largest 10.1 cm, 10 cases >5 cm). Resection margins were clear in all cases. We found no evidence of tumour recurrence or gastric stenosis at a median follow-up of 88 months. CONCLUSION: Transgastric laparo-endoscopic resection of junctional and pyloric tumours with low metastatic potential is technically feasible. This approach achieved clear resection margins in all our cases, with acceptable perioperative and longer-term outcomes.
