Esophageal Magnetic Compression Anastomosis in Esophageal Atresia Repair: A PRISMA-Compliant Systematic Review and Comparison with a Novel Approach.

The use of magnet compression to endoscopically create an esophageal anastomosis is an intriguing approach to esophageal atresia repair, but published cases with an existing available device have demonstrated mixed success. One major shortcoming has been the formation of subsequent severe, recalcitrant strictures after primary repair. To address the limitations of the existing device, we recently introduced and reported success with specially designed bi-radial magnets that exhibit a novel geometry and unique tissue compression profile. The aim of this study is to compare the outcomes using our novel device (novel group, NG) with those of previous reports which utilized the historical device (historic group, HG) in a PRISMA-compliant systematic review. Seven studies were eligible for further analysis. Additionally, one of our previously unreported cases was included in the analysis. Esophageal pouch approximation prior to primary repair was performed more frequently in the NG than in the HG (100% NG vs. 21% HG; p = 0.003). There was no difference in the overall postoperative appearance of postoperative stricture (95% HG vs. 100% NG; p = 0.64). The number of postoperative dilatations trended lower in the NG (mean 4.25 NG vs. 9.5 HG; p = 0.051). In summary, magnetic compression anastomosis adds a new promising treatment option for patients with complex esophageal atresia. Prior approximation of pouches and a novel magnet design have the potential to lower the rate of stricture formation

Antimicrobial susceptibility of biliary stents do not predict infectious complications after whipple.

BACKGROUND: Postoperative infectious complications after a pancreaticoduodenectomy remain a significant cause of morbidity. Studies have demonstrated that a preoperative biliary stent increases the risk of postoperative infectious complications. Few studies have investigated the specific preoperative biliary stent bacterial sensitivities to preoperative antibiotics and the effect on infectious complications. The goal of this study was to investigate if the presence of a preoperative biliary stent increases the risk of postoperative infectious complications in patients undergoing a pancreaticoduodenectomy. Additionally, we aimed to investigate biliary stent culture sensitivities to preoperative antibiotics and determine if those sensitivities impacted postoperative infectious complications after a pancreaticoduodenectomy. METHODS: A retrospective chart review of patients who had undergone a pancreaticoduodenectomy at a single institution tertiary care center from 2007 to 2018 was performed. Perioperative variables including microbiology cultures from biliary stents were collected and analyzed. RESULTS: A total of 244 patients underwent a pancreaticoduodenectomy. A preoperative biliary stent was present in 45 (18%) patients. Infectious complications occurred in 25% of those patients with a preoperative biliary stent, and 19% of those without (P = .37). Of those patients with a stent that was cultured intraoperatively, 92% grew bacteria and 61% of those were resistant to the preoperative antibiotics administered. Of the patients with a preoperative biliary stent and bacteria resistant to the preoperative antibiotics, 17% developed a postoperative infectious complication, compared with 20% if the bacteria cultured was susceptible to the preoperative antibiotics (P = .64). CONCLUSION: Infectious complications after pancreaticoduodenectomy are a significant cause of morbidity. Stent bacterial sensitivities to preoperative antibiotics did not reduce the postoperative infectious complications in the preoperative biliary stent group suggesting a multifactorial cause of infections

Feasibility of an implantable bioreactor for renal cell therapy using silicon nanopore membranes.

The definitive treatment for end-stage renal disease is kidney transplantation, which remains limited by organ availability and post-transplant complications. Alternatively, an implantable bioartificial kidney could address both problems while enhancing the quality and length of patient life. An implantable bioartificial kidney requires a bioreactor containing renal cells to replicate key native cell functions, such as water and solute reabsorption, and metabolic and endocrinologic functions. Here, we report a proof-of-concept implantable bioreactor containing silicon nanopore membranes to offer a level of immunoprotection to human renal epithelial cells. After implantation into pigs without systemic anticoagulation or immunosuppression therapy for 7 days, we show that cells maintain >90% viability and functionality, with normal or elevated transporter gene expression and vitamin D activation. Despite implantation into a xenograft model, we find that cells exhibit minimal damage, and recipient cytokine levels are not suggestive of hyperacute rejection. These initial data confirm the potential feasibility of an implantable bioreactor for renal cell therapy utilizing silicon nanopore membranes

Renal Embolization-Induced Uremic Swine Model for Assessment of Next-Generation Implantable Hemodialyzers

Reliable models of renal failure in large animals are critical to the successful translation of the next generation of renal replacement therapies (RRT) into humans. While models exist for the induction of renal failure, none are optimized for the implantation of devices to the retroperitoneal vasculature. We successfully piloted an embolization-to-implantation protocol enabling the first implant of a silicon nanopore membrane hemodialyzer (SNMHD) in a swine renal failure model. Renal arterial embolization is a non-invasive approach to near-total nephrectomy that preserves retroperitoneal anatomy for device implants. Silicon nanopore membranes (SNM) are efficient blood-compatible membranes that enable novel approaches to RRT. Yucatan minipigs underwent staged bilateral renal arterial embolization to induce renal failure, managed by intermittent hemodialysis. A small-scale arteriovenous SNMHD prototype was implanted into the retroperitoneum. Dialysate catheters were tunneled externally for connection to a dialysate recirculation pump. SNMHD clearance was determined by intermittent sampling of recirculating dialysate. Creatinine and urea clearance through the SNMHD were 76–105 mL/min/m2 and 140–165 mL/min/m2, respectively, without albumin leakage. Normalized creatinine and urea clearance measured in the SNMHD may translate to a fully implantable clinical-scale device. This pilot study establishes a path toward therapeutic testing of the clinical-scale SNMHD and other implantable RRT devices

Renal Embolization-Induced Uremic Swine Model for Assessment of Next-Generation Implantable Hemodialyzers

Reliable models of renal failure in large animals are critical to the successful translation of the next generation of renal replacement therapies (RRT) into humans. While models exist for the induction of renal failure, none are optimized for the implantation of devices to the retroperitoneal vasculature. We successfully piloted an embolization-to-implantation protocol enabling the first implant of a silicon nanopore membrane hemodialyzer (SNMHD) in a swine renal failure model. Renal arterial embolization is a non-invasive approach to near-total nephrectomy that preserves retroperitoneal anatomy for device implants. Silicon nanopore membranes (SNM) are efficient blood-compatible membranes that enable novel approaches to RRT. Yucatan minipigs underwent staged bilateral renal arterial embolization to induce renal failure, managed by intermittent hemodialysis. A small-scale arteriovenous SNMHD prototype was implanted into the retroperitoneum. Dialysate catheters were tunneled externally for connection to a dialysate recirculation pump. SNMHD clearance was determined by intermittent sampling of recirculating dialysate. Creatinine and urea clearance through the SNMHD were 76-105 mL/min/m2 and 140-165 mL/min/m2, respectively, without albumin leakage. Normalized creatinine and urea clearance measured in the SNMHD may translate to a fully implantable clinical-scale device. This pilot study establishes a path toward therapeutic testing of the clinical-scale SNMHD and other implantable RRT devices

Differential Effects of Collagen Prolyl 3-Hydroxylation on Skeletal Tissues

<div><p>Mutations in the genes encoding cartilage associated protein (<i>CRTAP</i>) and prolyl 3-hydroxylase 1 (P3H1 encoded by <i>LEPRE1</i>) were the first identified causes of recessive Osteogenesis Imperfecta (OI). These proteins, together with cyclophilin B (encoded by <i>PPIB</i>), form a complex that 3-hydroxylates a single proline residue on the α1(I) chain (Pro986) and has cis/trans isomerase (PPIase) activity essential for proper collagen folding. Recent data suggest that prolyl 3-hydroxylation of Pro986 is not required for the structural stability of collagen; however, the absence of this post-translational modification may disrupt protein-protein interactions integral for proper collagen folding and lead to collagen over-modification. P3H1 and CRTAP stabilize each other and absence of one results in degradation of the other. Hence, hypomorphic or loss of function mutations of either gene cause loss of the whole complex and its associated functions. The relative contribution of losing this complex's 3-hydroxylation versus PPIase and collagen chaperone activities to the phenotype of recessive OI is unknown. To distinguish between these functions, we generated knock-in mice carrying a single amino acid substitution in the catalytic site of P3h1 (<i>Lepre1^H662A</i>). This substitution abolished P3h1 activity but retained ability to form a complex with Crtap and thus the collagen chaperone function. Knock-in mice showed absence of prolyl 3-hydroxylation at Pro986 of the α1(I) and α1(II) collagen chains but no significant over-modification at other collagen residues. They were normal in appearance, had no growth defects and normal cartilage growth plate histology but showed decreased trabecular bone mass. This new mouse model recapitulates elements of the bone phenotype of OI but not the cartilage and growth phenotypes caused by loss of the prolyl 3-hydroxylation complex. Our observations suggest differential tissue consequences due to selective inactivation of P3H1 hydroxylase activity versus complete ablation of the prolyl 3-hydroxylation complex.</p></div

<i>Lepre1^H662A/H662A</i> mice have smaller collagen fibril diameter.

<p>Transmission EM analysis of collagen fibrils from skin revealed fibrils more homogenous in size in the <i>Lepre1^H662A/H662A</i> mice as compared to the wild-type littermates. Additionally, the collagen fibril diameters are slightly smaller, as quantified by a slight increase in the proportion of smaller diameter collagen fibrils. (bar = 100 nm). (N = 3,150 collagen diameters measured per animal, p<0.05).</p

<i>Lepre1^H662A/H662A</i> mice are normal in gross morphology.

<p>Analysis at 3 months by X-ray shows no difference in terms of skeletal patterning between genotypes (A). By growth curve analysis, there is no difference in weight at any time point over 3 months between <i>Lepre1^+/+</i> and <i>Lepre1^H662A/H662A</i> mice (B). We assessed rhizomelia by measuring the length of both the femur and tibia and computing the ratio. Comparing <i>Lepre1^+/+</i> to <i>Lepre1^H662A/H662A</i> mice, we observed no difference in the length of the femur, tibia, or their ratio (C). N = 10, both genotypes.</p