Treatment of Aortoiliac Occlusive Disease with the Endologix AFX Unibody Endograft.

OBJECTIVE/BACKGROUND: Aorto-bifemoral bypass remains the gold standard for treatment of aortoiliac occlusive disease (AIOD) in patients with advanced (TASC D) lesions, but has significant associated morbidity and mortality. Treatment with a unibody stent-graft positioned at the aortic bifurcation is a potential endovascular option for the treatment of AIOD. The current study examines the safety, efficacy, and early patency rates of the Endologix AFX unibody stent-graft for treatment of AIOD. METHODS: A multicenter retrospective review was conducted of patients treated exclusively for AIOD with the AFX device. Primary, assisted primary, and secondary patency rates were noted. Clinical improvement was assessed using Rutherford classification and ankle brachial index. Mean duration of follow-up was 22.2 ± 11.2 months. Ninety-one patients (56 males [62%]) were studied. RESULTS: Sixty-seven patients (74%) presented with lifestyle-limiting intermittent claudication and the remaining 24 (26%) had critical limb ischemia. Technical success was 100%. Complications included groin infection (n = 4 [4%]), groin hematoma (n = 4 [4%]), common iliac rupture (n = 4 [4%]), iliac dissection (n = 4 [4%]), and thromboembolic event (n = 3 [3%]; one femoral, one internal iliac artery, and one internal iliac with bilateral popliteal/tibial thromboemboli). Thirty-day mortality was 1% (1/91) resulting from a case of extensive pelvic thromboembolism. At 1 year, 73% of patients experienced improvement in Rutherford stage of -3 or greater compared with baseline. Nine patients (10%) required 16 secondary interventions. At all time points, primary patency rates were > 90%, assisted patency rates were > 98%, and secondary patency rates were 100%. CONCLUSION: This is the largest study to examine the use of the Endologix AFX unibody stent-graft for the treatment of AIOD. Use of the AFX stent-graft appears to be a safe and effective endovascular treatment for complex AIOD.

Experience and technique for the endovascular management of iatrogenic subclavian artery injury.

BACKGROUND: Inadvertent subclavian artery catheterization during attempted central venous access is a well-known complication. Historically, these patients are managed with an open operative approach and repair under direct vision via an infraclavicular and/or supraclavicular incision. We describe our experience and technique for endovascular management of these injuries. METHODS: Twenty patients were identified with inadvertent iatrogenic subclavian artery cannulation. All cases were managed via an endovascular technique under local anesthesia. After correcting any coagulopathy, a 4-French glide catheter was percutaneously inserted into the ipsilateral brachial artery and placed in the proximal subclavian artery. Following an arteriogram and localization of the subclavian arterial insertion site, the subclavian catheter was removed and bimanual compression was performed on both sides of the clavicle around the puncture site for 20 min. A second angiogram was performed, and if there was any extravasation, pressure was held for an additional 20 min. If hemostasis was still not obtained, a stent graft was placed via the brachial access site to repair the arterial defect and control the bleeding. RESULTS: Two of the 20 patients required a stent graft for continued bleeding after compression. Both patients were well excluded after endovascular graft placement. Hemostasis was successfully obtained with bimanual compression over the puncture site in the remaining 18 patients. There were no resultant complications at either the subclavian or the brachial puncture site. CONCLUSION: This minimally invasive endovascular approach to iatrogenic subclavian artery injury is a safe alternative to blind removal with manual compression or direct open repair.

Multidimensional characterization of carotid artery stenosis using CT imaging: a comparison with ultrasound grading and peak flow measurement.

PURPOSE: Clinical decision making for carotid surgery depends largely upon stenosis grade. While digital subtraction angiography remains the gold standard for stenosis grading, many physicians use less invasive modalities. The purpose of this study was to compare the results of multidimensional Computed tomography (CTA) with ultrasound (US) grading and peak flow velocity (PSV). METHODS: 37 stenosed carotid arteries were studied retrospectively in 36 consecutive patients. US grading and PSV were compared to multidimensional CTA analysis (diameter, area and volumetric measurements), performed by a medical software company. Calculations of stenosis percentage on CTA were made using the NASCET and ECST methodology. Diameter measurements were also performed by a neuroradiologist. RESULTS: All CTA diameter, area and volume measurements had only modest correlation with PSV (r<0.5) and ultrasound grading (p<0.5). There was concordant classification of stenosis grades in only 40-60% of cases. CTA diameter, area and volume measurements had good correlation (0.69

Expression and role of laminin-1 in mouse pancreatic organogenesis.

Previous studies have suggested that basement membrane alone may induce ductal differentiation and morphogenesis in the undifferentiated embryonic pancreas. The mechanism by which this induction occurs has not been investigated. Studies of other organ systems such as the lungs and mammary glands, where differentiation has been shown to be induced by basement membrane, have suggested a major role for laminin as a mediator of ductal or tubular morphogenesis and differentiation. We first defined the ontogeny of laminin-1 in the developing mouse pancreas. To determine the specific role of basement membrane laminin in pancreatic ductal morphogenesis and differentiation, we microdissected 11-day mouse embryonic pancreatic epithelium free from its surrounding mesenchyme and then suspended the explants in a 3-dimensional organ culture to allow us to assay cell differentiation and morphogenesis. When the pancreatic epithelium buds off the foregut endoderm, the pancreatic mesenchyme diffusely expresses laminin-1. This laminin subsequently organizes to the interface between the epithelium and the mesenchyme by E12.5. As gestation progresses, epithelial cells in direct contact with laminin-1 seem to differentiate into ducts and acini, whereas those spared intimate contact with laminin-1 appeared to organize into islets. Although basement membrane gel could induce pancreatic ductal morphogenesis of embryonic pancreatic epithelium, this induction was blocked when we added neutralizing antibodies against any of the following: 1) laminin (specifically laminin-1), 2) the "cross-region" of laminin-1, and 3) the alpha6 moiety of the integrin receptor, which is known to bind laminins. Immunohistochemistry, however, showed that pancreatic duct cell-specific differentiation (carbonic anhydrase II) without ductal morphogenesis was still present, despite the blockage of duct morphogenesis by the anti-laminin-1 neutralizing antibodies. Interestingly, there appeared to be a decrease in carbonic anhydrase II expression over time when the epithelia were grown in a collagen gel, rather than in a basement membrane gel. The pattern of laminin-1 expression in the embryonic pancreas supports the conclusion that laminin-1 is important in the induction of exocrine (ducts and acini) differentiation in the pancreas. Furthermore, our data demonstrate that 1) pancreatic ductal morphogenesis appears to require basement membrane laminin-1 and an alpha6-containing integrin receptor; 2) the cross-region of basement membrane laminin is a biologically active locus of the laminin molecule necessary for pancreatic ductal morphogenesis; 3) duct-specific cytodifferentiation, in the form of carbonic anhydrase II expression, is not necessarily coupled to duct morphogenesis; and 4) the basement membrane gel may contain components (e.g., growth factors) other than laminin-1 that can sustain both carbonic anhydrase II expression and, possibly, the capacity to form ducts, despite the absence of duct structures.

Mapping a social network of heterosexuals at high risk for HIV infection.

OBJECTIVE: To determine how heterosexuals at risk for HIV infection interconnect in social networks and how such relationships affect HIV transmission. DESIGN: Cross-sectional study with face-to-face interviews to ascertain sociosexual connections; serologic testing. PARTICIPANTS: Prostitute women (n = 133), their paying (n = 129) and non-paying (n = 47) male partners; injecting drug users (n = 200) and their sex partners (n = 41). Participants were recruited in sexually transmitted disease and methadone clinics, an HIV-testing site, and through street outreach in Colorado Springs, Colorado, USA. MAIN OUTCOME MEASURES: Reported behaviors, risk perceptions, sociosexual linkages, and HIV prevalence. RESULTS: Respondents were well informed, but reported engaging in high-risk behaviors frequently. Nevertheless, over 70% of respondents perceived themselves to be at low risk for HIV infection. The 595 respondents identified a social network of 5162 people to which they belonged. Network analytic methods indicated 147 separate connected components of this network; eight of the 19 HIV-positive individuals in the network were located in smaller components remote from the largest connected component. CONCLUSION: The isolated position of HIV-positive individuals may serve as a barrier to HIV transmission and may account for the lack of diffusion of HIV in heterosexual populations in this region. Network analysis appears useful for understanding the dynamics of disease transmission and warrants further development as a tool for intervention and control.

Basement membrane exposure defines a critical window of competence for pancreatic duct differentiation from undifferentiated pancreatic precursor cells.

We previously showed that the undifferentiated pancreatic epithelium can differentiate into islets, ducts, or acini depending on its milieu and that laminin is necessary for pancreatic duct formation. Therefore we wanted to study the plasticity of laminin-induced duct differentiation the better to understand mechanisms of pancreatic duct lineage selection induced by basement membrane. Mouse embryonic pancreases were dissected at gestational day 11 (E11.5), and epithelium was isolated from its surrounding mesenchyme. Some epithelia were cultured in a collagen gel devoid of laminin. These epithelia were "rescued" at days 1-7 of culture by transferring them to a laminin-rich matrix (Matrigel) for 7 additional days. Other epithelia were instead first cultured in Matrigel, and then placed into collagen. Immunohistochemistry was performed for insulin, amylase, and carbonic anhydrase II. Pancreatic epithelia rescued from collagen into laminin during days 1-4 after harvest were still able to form ducts, whereas epithelia deprived of laminin for longer than this 4-day window were not. Pancreatic epithelia exposed to laminin for as little as 1 day, and then placed into collagen, still retained the ability to make ducts. Thus there is a clear cut-off in the development of the pancreatic epithelium at E11.5, after which laminin appears necessary to induce duct formation. We believe that such "windows of competence" in embryonic development imply that developmental programs in the embryo allow some flexibility.

Ontogeny of activin B and follistatin in developing embryonic mouse pancreas: implications for lineage selection.

Activin, a member of the transforming growth factor-beta superfamily, has been shown to be a critical regulator in exocrine and endocrine pancreas formation. The purpose of our study was to describe the ontogeny of activin B and its inhibitor, follistatin, in developing pancreas and to elucidate potential mechanisms for exocrine and endocrine lineage selection. Mouse embryonic pancreata were dissected at various ages (day 10 [E10.5] to birth [E18.5]), sectioned, and immunostained for activin B (one of two existing isomers, A and B), follistatin, insulin, and glucagon. In addition, reverse transcriptase-polymerase chain reaction was employed to determine the messenger RNA expression of follistatin in isolated pancreatic epithelia and mesenchyme of various ages. Activin B was first detected at E12.5 in epithelial cells coexpressing glucagon. At E16.5 these coexpressors appeared as clusters in close proximity to early ducts. By E18.5 activin B was localized to forming islets where cells coexpressed glucagon and were arranged in the mantle formation characteristic of mature alpha cells. Follistatin was found to be ubiquitous in pancreatic mesenchyme at early ages by immunohistochemical analysis, disappearing sometime after E12.5. Follistatin reappeared in E18.5 islets and remains expressed in adult islets. Follistatin messenger RNA was first detected in epithelium at E11.5, preceding its protein expression in islets later in gestation. We propose that mesenchyme-derived follistatin inhibits epithelium-derived activin at early embryonic ages allowing for unopposed exocrine differentiation and relative suppression of endocrine differentiation. At later ages the decrease in the amount of mesenchyme relative to epithelium and the subsequent drop in follistatin levels liberates epithelial activin to allow differentiation of endocrine cells to form mature islets by the time of birth.

Successful limb reperfusion using prolonged intravascular shunting in a case of an unstable trauma patient--a case report.

When peripheral vascular injuries present in conjunction with life threatening emergencies, controlling hemorrhage from a peripheral blood vessel may take initial priority, however, sacrificing a limb to preserve life is a well-established dictum. The use of intravascular shunts has allowed arterial and venous injuries to be controlled and temporized while treating other injuries. Typically, intravascular shunts are used for short time periods while orthopedic injuries are repaired or other life threatening injuries are managed. The following case demonstrates the long-term use of an intravascular arterial shunt to treat a traumatic transection of the common femoral artery and vein in a patient with an open pelvic fracture from blunt trauma. A 20-year-old woman fell between a subway platform and an oncoming train. She sustained a crush injury to her lower extremity and pelvis as she was pinned between the train and platform. The patient presented with active hemorrhage from a groin laceration, quickly became hemodynamically unstable, and was brought to the operating room. In addition to a pelvic fracture with massive pelvic hematoma she sustained a complete transection of the bifurcation of the common femoral artery (CFA), the common femoral vein (CFV), and associated orthopedic injuries. Vascular shunts were placed in the common femoral artery and vein. The patient became hypotensive from an expanding retroperitoneal hematoma. Pelvic bleeding was controlled with angioembolization and the venous injury was repaired. At this time the patient became cold, acidotic, and coagulopathic. It was thought unsafe to proceed with the arterial repair and it was elected to keep her arterial shunts in place and perform a planned reexploration in 24 hours after correcting her physiologic status. The patient returned to the operating room for an elective repair of her CFA the following day. Her shunt had remained patent throughout this time. She underwent a reverse saphenous vein graft from her CFA to her SFA. After a prolonged hospital course she was ultimately transferred to a rehabilitation center with intact pulses in both lower extremities. This case demonstrates the effectiveness of prolonged (>6 hours) use of an intravascular shunt as part of damage control surgery for peripheral arterial and venous injuries. In a patient who would otherwise undergo an amputation for their injury, the risk of shunt thrombosis, or infection, during damage control resuscitation may not be a contraindication for placement.

An in vitro mouse model of cleft palate: defining a critical intershelf distance necessary for palatal clefting.

It is unclear whether cleft palate formation is attributable to intrinsic biomolecular defects in the embryonic elevating palatal shelves or to an inability of the shelves to overcome a mechanical obstruction (such as the tongue in Pierre Robin sequence) to normal fusion. Regardless of the specific mechanism, presumably embryonic palatal shelves are ultimately unable to bridge a critical distance and remain unapproximated, resulting in a clefting defect at birth. We propose to use a palate organ culture system to determine the critical distance beyond which embryonic palatal shelves fail to fuse (i.e., the minimal critical intershelf distance). In doing so, we hope to establish an in vitro cleft palate model that could then be used to investigate the contributions of various signaling pathways to cleft formation and to study novel in utero treatment strategies. Palatal shelves from CD-1 mouse embryos were microdissected on day 13.5 of gestation (E13.5; term = 19.5 days), before fusion. Using a standardized microscope ocular grid, paired palatal shelves were placed on a filter insert at precisely graded distances ranging from 0 (in contact) to 1.9 mm (0, 0.095, 0.19, 0.26, 0.38, 0.48, 0.57, 0.76, 0.95, and 1.9 mm). A total of 68 paired palatal shelves were placed in serum-free organ culture for 96 hours (n = 68). Sample sizes of 10 were used for each intershelf distance up to and including 0.48 mm (n = 60). For intershelf distances of 0.57 mm and greater, two-paired palatal shelves were cultured (n = 8). All specimens were assessed grossly and histologically for palatal fusion. Palatal fusion occurred in our model only when intershelf distances were 0.38 mm or less. At 0.38 mm, eight of 10 palates appeared grossly adherent, whereas six of 10 demonstrated clear fusion histologically with resolution of the medial epithelial seam and continuity of the palatal mesenchyme. None of the 18 palates fused when placed at intershelf distances of 0.48 mm or greater. Using our selected intershelf distances as a guideline, we have established an approximate minimal critical intershelf distance (0.48 mm) at which we can reliably expect no palatal fusion. Culturing palatal shelves at intershelf distances of 0.48 mm or greater results in nonfusion or clefting in vitro. This model will allow us to study biomolecular characteristics of unfused or cleft palatal shelves in comparison with fused shelves. Furthermore, we plan to study the efficacy of grafting with exogenous embryonic mesenchyme or candidate factors to overcome clefting in vitro as a first step toward future in utero treatment strategies.

Immunolocalization of fibroblast growth factor receptors 1 and 2 in mouse palate development.

Recent evidence has implicated mutations of fibroblast growth factor receptors (FGF-R) in the pathogenesis of craniosynostotic syndromes. Cleft palate can be a component of such syndromes. The expression of FGF-R1 and FGF-R2 has been delineated in normally developing cranium, where they seem to regulate cellular differentiation and proliferation, respectively. The specific role of fibroblast growth factor signaling in mammalian palate development is unclear. The authors investigated the patterns of expression of FGF-R1 and FGF-R2 throughout mouse palatal development in the embryo. Time-dated CD-1 mouse heads (n = 135) were harvested at embryonic ages 12.5, 13.5, 14.5, 15.5, and 16.5 days (term gestation = 19.5 days), fixed in paraformaldehyde, embedded in paraffin, and sectioned. In addition, paired palatal shelves (n = 30) were isolated by means of microdissection from embryonic day--13.5 embryos, grown on Millipore filters in serum-free medium in vitro for 24, 48, 72, or 96 hours and processed for histological analysis. Immunohistochemical analysis for FGF-R1 and FGF-R2 was performed on the in vivo and in vitro specimens. FGF-R1 and FGF-R2 were found to be specifically expressed in the epithelium of the developing palatal shelves from the time of their outgrowth from the maxillary processes through completion of fusion in vivo and in vitro. Expression of both receptors was particularly strong during the phases of medial epithelial-medial epithelial contact between the individual shelves, through the formation of the medial epithelial seam, to the ultimate dissolution of the seam. Such a pattern of expression seems to implicate fibroblast growth factor signaling in the regulation of the critical phase of fusion of the bilateral shelves. The expression of both FGF-R1 and FGF-R2 in the lateral palatal mesenchyme, where such secondary structures as tooth primordia and bone begin to appear, also suggests a role for fibroblast growth factor signaling in the induction of ongoing differentiation and maturation of the palate after fusion. These data suggest that fibroblast growth factor signaling may play a role in the epithelial-mesenchymal interactions that dictate fusion and maturation of the developing palate. Furthermore, the data are consistent with the correlation of cleft palate formation with aberrant fibroblast growth factor signaling.

Defective fibroblast growth factor signaling allows for nonbranching growth of the respiratory-derived fistula tract in esophageal atresia with tracheoesophageal fistula.

BACKGROUND/PURPOSE: The fistula tract in esophageal atresia with tracheoesophageal fistula (EA-TEF) appears to arise from a trifurcation of the embryonic lung bud. Subsequently, it does not branch like the other bronchi, which also arise from the lung bud. Previous results have implied that aberrant mesenchymal-epithelial signaling in the developing foregut, possibly involving fibroblast growth factors, may allow for the nonbranching growth of the fistula, and the ultimate development of the fistula tract in TEF. METHODS: Adriamycin injections into pregnant rat dams induced EA-TEF formation in rat embryos. Control and Adriamycin-exposed embryos were harvested on the 13th gestational day, and the developing foregut was isolated with microdissection. mRNA was isolated from the developing fistula tract, embryonic lung, and normal embryonic esophagus. Reverse transcription-polymerase chain reaction (RT-PCR) for the IIIb splice variant of the FGF2R receptor was performed. Foregut specimens also were processed for histologic analysis, and immunofluorescence for FGF1 was performed. RESULTS: FGF2R-IIIb is specifically absent from the developing fistula tract in TEF, whereas it is present in the normal developing lung and esophagus. FGF1 also is uniquely absent from the developing fistula tract, but it is present in the normal lung mesenchyme. CONCLUSIONS: FGF1, FGF7, and FGF10 are critical mesenchymal factors that mediate proliferation and branching morphogenesis by the developing respiratory epithelium. The absence of FGF2R-IIIb, the obligate common receptor for FGF7 and FGF10, from the fistula tract, and the absence of FGF1 in the fistula tract mesenchyme, collectively imply the absence of a specific FGF signaling pathway in the developing fistula tract. This absence of FGF signaling could explain the lack of branching by the developing fistula tract as it grows caudally in the abnormally developing embryo. Downregulation of these components of the FGF signaling pathways may allow for a patterned compensation by the embryo for the proximal foregut atresia in this anomaly. This compensation may then reestablish gastrointestinal continuity as the fistula tract connects to the developing stomach.

Left subclavian artery coverage during TEVAR: is revascularization necessary?

Thoracic endovascular aortic repair (TEVAR) has rapidly become a viable and accepted treatment option for atherosclerotic aortic aneurysms as well as a variety of other aortic pathologies including ulcers, dissection, coarctation and disruption. Left subclavian artery (LSA) coverage is often necessary to achieve proximal seal in up to 40% of patients treated with TEVAR. The management of the LSA in this cohort of patients remains controversial. Studies in support of routine pre-operative LSA revascularization show that coverage of the LSA during TEVAR is associated with an increased risk of stroke, paraplegia and arm ischemia. Other studies show that intentional coverage of the LSA without revascularization is not associated with increased morbidity and lends support to those who advocate more selective LSA revascularization during TEVAR (i.e. in those patients with patent LIMA-coronary bypass, dominant or isolated left vertebral artery, or a functioning left upper extremity (LUE) dialysis arteriovenous fistula). This paper is intended to review the literature comparing routine and selective LSA revascularization after TEVAR to determine the best management strategy.

Percutaneous drainage of aortic aneurysm sac abscesses following endovascular aneurysm repair.

PURPOSE: To report preliminary experiences with the treatment of aortic aneurysm sac abscesses following prior endovascular aortic aneurysm repair (EVAR) using computerized tomography (CT)-guided percutaneous drainage. CASE REPORTS: Three patients aged 73 to 78 years with aortic aneurysm sac infections following prior EVAR, 2 of which were associated with aortoduodenal fistula, underwent CT-guided percutaneous drainage and catheter placement. One patient had complete resolution of the aortic aneurysm sac abscess following percutaneous drainage; 1 patient was stabilized to eventual extraanatomic bypass, graft explantation, and fistula repair; and 1 patient was temporized to debridement and fistula repair with endograft preservation. CONCLUSION: CT-guided percutaneous drainage may be a helpful therapy in selected patients for the treatment of aortic aneurysm sac infections following EVAR.

Regional nerve block allows for optimization of planning in the creation of arteriovenous access for hemodialysis by improving superficial venous dilatation.

Durable vascular access for hemodialysis remains a critical issue in end-stage renal disease patients. Creation of an autogenous arteriovenous (AV) fistula in the most distal location of the nondominant extremity is the preferred technique and provides superior patency over an AV graft. Others have shown that regional anesthesia in the form of axillary block results in the dilatation of the native veins and allows for their increased utilization in creating AV fistulae. We report on 26 patients undergoing creation of a vascular access for hemodialysis. Regional anesthesia consisting of axillary nerve block was used in all cases. All surgical plans with regard to the site and type of access were made based on the physical exam and ultrasound vein measurements taken prior to surgery. On the day of surgery patients were reevaluated with venous ultrasound using tourniquet before and after administration of the regional block. The previously determined operative plan either remained unchanged or was modified depending on the venous dilatation noted after administration of regional block. Among 26 patients, average vein diameter increased from 0.29 +/- 0.12 cm to 0.34 +/- 0.11 cm (P = 0.008). Twenty-one of 26 patients had no modification in operative plan (group 1). Five had some modification of the original operative plan (group 2): AV graft to a brachial vein transposition (n = 2), AV graft to a Cimino fistula (n = 2), and brachiocephalic to a Cimino (n = 1). The average follow-up for all patients was 82.6 +/- 75.6 days and did not differ between the groups. There was one failure in a patient from group 1, and there was no significant difference in the patency rate between study groups (P = 0.29). Following regional nerve block, operative plans in patients undergoing AV access surgery were modified in 29.4% of patients undergoing creation of an AV access for hemodialysis; either from graft to fistula creation or from the proximal to more distal fistula site. The routine use of regional anesthesia as well as intraoperative ultrasound during AV access surgery can lead to improved site selection and increased opportunity for AV fistula creation.

Defective epithelial-mesenchymal interactions dictate the organogenesis of tracheoesophageal fistula.

We have previously suggested that the fistula tract in esophageal atresia with tracheoesophageal fistula (EA/TEF) arises from a trifurcation of the embryonic lung bud. Thus, it appears to be a respiratory-derived structure, and expresses the lung-specific transcription factor TTF-1 in its epithelium. The fistula tract does not give rise to lungs like the other branches from the bud. It grows caudally until it fistulizes with the stomach. We hypothesized that epithelial-mesenchymal interactions (EMI) dictate the differential pattern of growth of the respiratory-derived fistula tract in EA/TEF. EA/TEF was induced in rat embryos via prenatal exposure to adriamycin. Microdissection was performed on E13.5 embryos to isolate developing lung bud, fistula tract, or esophagus from adriamycin-treated or control animals, respectively. The mesenchyme and epithelium from each of these foregut structures were separated. The individual epithelia were recombined with each of the various mesenchymes and grown in culture. They were assayed for relative degrees of branching. Isolated lung-bud epithelia (LBE) or fistula epithelium were also cultured in Matrigel with exogenous fibroblast growth factors (FGF) and subsequently assayed for branching. The fistula-tract mesenchyme relatively inhibited branching of lung epithelium. The epithelium of the fistula tract could be induced to branch by non-fistula (lung or esophageal) mesenchyme. The fistula-tract and adriamycin-treated LBE both branched in response to FGF1. In contrast, neither responded to FGF7 or FGF10. EMI are defective in the developing EA/TEF. The inability to respond to FGF7 and FGF10 suggests an epithelial defect involving the receptor FGF2R-IIIb, to which these mesenchymal factors obligately bind. Thus, the mesenchyme around the developing fistula tract may lack an FGF branching morphogen(s), such as FGF1. Hence, this mesenchyme is unable to induce branching of respiratory epithelia and allows the middle branch of the embryonic tracheal trifurcation to grow caudally as an unbranched tube until it fistulizes into the stomach.

Patterning of the "distal esophagus" in esophageal atresia with tracheo-esophageal fistula: is thyroid transcription factor 1 a player?

BACKGROUND: We have recently proposed that the "distal esophagus" in esophageal atresia with tracheo-esophageal fistula (EA/TEF) is actually embryologically derived from the middle branch of a trifurcation of the embryonic lung bud, which subsequently grows caudally in the foregut to connect with the developing stomach. We hypothesized that differential mRNA expression of the lung-specific patterning transcription factor, thyroid transcription factor 1 (TTF-1), in the developing fistula tract in TEF relative to the bronchi (the other branches of the lung bud trifurcation) might explain the unique nonbranching pattern of growth of the fistula tract. MATERIALS AND METHODS: EA/TEF was induced in Sprague-Dawley rat embryos via intraperitoneal injection of 2.2 mg/kg adriamycin into pregnant dams on Days 6-9 of gestation. The foregut from embryos developing EA/TEF and from control embryos (no adriamycin) were isolated on Gestational Days 13.5, 15.5, and 17.5 (term = 21 days). Some were processed for whole-mount in situ hybridization for TTF-1, while others were embedded and sectioned for histologic analysis via in situ hybridization for TTF-1. RESULTS: The expression of the respiratory-specific transcription factor TTF-1 is conserved in the epithelium of the developing fistula tract in TEF. The pattern of expression of TTF-1 in the fistula tract mirrors the expression in the large airways of the developing lungs, despite the fact that the fistula tract does not form secondary branches to give rise to a lung. CONCLUSIONS: The fistula tract in TEF is a respiratory-derived structure that expresses the lung-specific transcription factor TTF-1 throughout its development in the foregut. Contrary to the patterning role that it normally plays in the developing lung, TTF-1 does not induce branching morphogenesis in the fistula tract. Thus, the nonbranching pattern of growth of the fistula tract may be attributable to local mesenchymal-epithelial interactions that override TTF-1 patterning activity.

In vitro validation of duct differentiation in developing embryonic mouse pancreas.

BACKGROUND: Early embryonic pancreatic epithelia have the capacity for either endocrine or exocrine lineage commitment. Recent studies demonstrated the pluripotential nature of these undifferentiated cells. Isolated pancreatic epithelia grown under the renal capsule formed primarily islets. However, when these same epithelia were grown in a basement-membrane-rich gel (Matrigel) they formed mostly ducts. Currently, there is no model for in vitro pancreatic duct formation and therefore, the mechanism of duct morphogenesis has never been described. The purpose of this study was to provide such a model by characterizing the expression of two duct markers, carbonic anhydrase II (CAII) and the cystic fibrosis transmembrane conductance regulator (CFTR), in isolated undifferentiated pancreatic epithelia grown in vitro. MATERIALS AND METHODS: We microdissected embryonic pancreases at Embryonic Days (E)9.5-11.5 and performed RT-PCR for CAII and CFTR on E9.5 whole pancreases, E10. 5 and E11.5 epithelia, as well as E11.5 epithelia grown for 7 days in Matrigel. Next we performed in situ hybridization for CAII and CFTR and immunohistochemistry for CAII on E11.5 epithelia grown for 7 days in Matrigel. RESULTS: Early, undifferentiated embryonic pancreatic epithelium does not express CAII and CFTR by RT-PCR. When E11.5 epithelia were grown for 7 days in Matrigel, however, gene expression for both markers is upregulated as ducts form. Furthermore, CAII was seen by IHC and both CAII and CFTR were seen by in situ hybridization in the ducts after 7 days in Matrigel. CONCLUSIONS: These data validate our in vitro system as a model for studying the mechanism of normal pancreatic duct differentiation and may potentially help us to understand the faulty mechanism involved in pancreatic ductal carcinogenesis.

Initial successful management of type I endoleak after endovascular aortic aneurysm repair with n-butyl cyanoacrylate adhesive.

OBJECTIVE: Transcatheter embolization with coils and other agents has been described as a treatment method for type II endoleak after endovascular aortic aneurysm repair (EVAR). Type I endoleak has not been treated commonly with such therapies, although most investigators believe they warrant definitive intervention. The liquid adhesive n-butyl 2-cyanoacrylate (n-BCA) is often used to treat congenital arteriovenous malformations. The objective of this study is to report our initial experience in treating type I endoleak with n-BCA and with a variety of other interventions. METHODS: A retrospective review was performed of 270 patients who underwent EVAR at our institution between January 1994 and December 2002. Of these, 24 patients had type I endoleak (8.9%), diagnosed either intraoperatively (n = 13, 52%) or during follow-up (n = 12, 48%). Among these 24 patients, 17 had proximal leaks and the remaining 8 patients had distal leaks. These cases form the focus of this study. RESULTS: Twenty-two leaks required endovascular intervention, with the following success rate: n-BCA, 12 of 13 cases (92.3%); extender cuffs, 4 of 5 cases (80%); coils with or without thrombin, 3 of 4 cases (75%). In one patient with persistent endoleak despite attempted endovascular intervention the device ultimately was surgically explanted, and the patient did well. Of six patients with endoleak initially managed expectantly, two eventually underwent attempts at definitive intervention, both with n-BCA. Three sealed spontaneously before definitive intervention could be performed; and in one 97-year-old patient who refused intervention, the aneurysm subsequently ruptured and the patient died. In total, 13 patients with type I endoleak underwent n-BCA transcatheter embolotherapy. No serious complications were directly related to this therapy. Colon ischemia developed in one patient, and was believed to be a result of thromboembolism during wire and catheter manipulation rather than n-BCA treatment. Twelve of these 13 leaks remain sealed at mean follow-up of 5.9 months (range, 0-19 months). CONCLUSION: Our initial use of n-BCA occlusion suggests that it may be an effective and safe method of treatment of type I endoleak after EVAR. In particular, n-BCA embolotherapy may be especially useful in treating type I endoleak not amenable to placement of extender cuffs. Larger case series and longer follow-up are needed before this treatment is more broadly recommended. Type I endoleak after EVAR can be treated successfully with a variety of endovascular methods, and surgical explantation is rarely required.

Transforming growth factor-beta 1 in the developing mouse pancreas: a potential regulator of exocrine differentiation.

Transforming growth factor-beta 1 (TGF-beta 1) is known to regulate cell growth, differentiation, and function in developing mammalian systems. Altering TGF-beta 1 expression in the developing pancreas has been shown to affect both exocrine and endocrine development, suggesting that it is an important regulator of pancreatic organogenesis. We proposed to examine the ontogeny of TGF-beta 1 mRNA expression in the developing pancreas, as well as characterize the patterns of relative TGF-beta 1 gene expression and activity. We performed in situ hybridization for TGF-beta 1 on pancreas specimens obtained from CD-1 mice on gestational days 12.5 (E12.5), 15.5 (E15.5), and 18.5 (18.5). We also isolated mRNA from the pancreas on each of these days and performed a semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR) to assess relative TGF-beta 1 expression as a function of gestational age. Finally, we performed a TGF-beta 1 ELISA with media conditioned by embryonic pancreas from gestational days 15.5 and 18.5. By in situ hybridization, TGF-beta 1 mRNA is expressed exclusively in the E12.5 pancreatic epithelium, sparing the surrounding mesenchyme. As pancreatic organogenesis progresses, TGF-beta 1 mRNA expression localizes predominantly to the developing acini. TGF-beta 1 gene expression appears modest through E15.5 but is upregulated near the end of gestation, at E18.5. TGF-beta 1 activity, by ELISA, is also upregulated at E18.5. TGF-beta 1 may thus be a modulator of pancreatic organogenesis. Modest TGF-beta 1 expression through E15.5 may be permissive for exocrine lineage selection. TGF-beta 1 expression may then become critical for terminal acinar differentiation. Upregulated TGF-beta 1 expression at the end of gestation may be important for islet formation, and it may be necessary to inhibit continued proliferation and differentiation of pluripotent cells within the pancreatic ductal epithelium.