Case series of aortic arch disease treated with branched stent-grafts.

BACKGROUND: Surgical repair of aortic arch pathology is complex and associated with significant morbidity and mortality. Alternative approaches have been developed to reduce these risks, including the use of thoracic stent-grafts with fenestrations or in combination with bypass procedures to maintain supra-aortic trunk blood flow. Branched stent-grafts are a novel approach to treat aortic arch pathology. METHODS: Consecutive patients with aortic arch disease presenting to a single university hospital vascular centre were considered for branched stent-graft repair (October 2010 to January 2017). Patients were assessed in a multidisciplinary setting including a cardiologist, cardiac surgeon and vascular surgeon. All patients were considered prohibitively high risk for standard open surgical repair. The study used reporting standards for endovascular aortic repair and PROCESS (Preferred Reporting of Case Series in Surgery) guidelines. RESULTS: Some 30 patients (25 men) underwent attempted branch stent-graft repair. Mean age was 68 (range 37-84) years. Eighteen patients had chronic aortic dissection, 11 patients had an aneurysm and one had a penetrating ulcer. Fourteen patients had disease in aortic arch zone 0, six in zone 1 and ten in zone 2. Twenty-five patients had undergone previous aortic surgery and 24 required surgical revascularization of the left subclavian artery. Technical success was achieved in 27 of 30 patients. Four patients had an endoleak (type Ia, 1; type II, 3). The in-hospital mortality rate was three of 30. Mean length of follow-up was 12·0 (range 1·0-67·8) months, during which time 12 patients required an aortic-related reintervention. CONCLUSION: Repair of aortic arch pathology using branched stent-grafting appears feasible. Before widespread adoption of this technology, further studies are required to standardize the technique and identify which patients are most likely to benefit.

Changes in Renal Anatomy After Fenestrated Endovascular Aneurysm Repair.

OBJECTIVE: To assess short- and long-term movement of renal arteries after fenestrated endovascular aortic repair (FEVAR). METHODS: Consecutive patients who underwent FEVAR at one institution with a custom-made device designed with fenestrations for the superior mesenteric (SMA) and renal arteries, a millimetric computed tomography angiography (CTA), and a minimum of 2 years' follow-up were included. Angulation between renal artery trunk and aorta, clock position of the origin of the renal arteries, distance between renal arteries and SMA, and target vessel occlusion were retrospectively collected and compared between the pre-operative, post-operative (<6 months), and last (>12 months) CTA. RESULTS: From October 2004 to January 2014, 100 patients met the inclusion criteria and 86% of imaging was available for accurate analysis. Median follow-up was 27.3 months (22.7-50.1). There were no renal occlusions. A significant change was found in the value of renal trunk angulation of both renal arteries on post-operative compared with pre-operative CTA (17° difference upward [7.5-29], p < .001), but no significant change thereafter (p = .5). Regarding renal clock positions (7.5° of change equivalent to 15 min of renal ostial movement): significant anterior change was found between post-operative and pre-operative CTA (15 min [0-30], p = .03 on the left and 15 min [15-30], p < .001 on the right), without significant change thereafter (15 min [0-30], p = .18 on the left and 15 min [0-15] on the right, p = .28). No changes were noted on the distance between renal and SMA ostia (difference of 1.65 mm [1-2.5], p = .63). CONCLUSION: The renal arteries demonstrate tolerance to permanent changes in angulation after FEVAR of approximately 17° upward trunk movement and of 15-30 min ostial movement without adverse consequences on patency after a median of more than 2 years' follow-up. The distance between the target vessels remained stable over time. These results may suggest accommodation to sizing errors and thus a compliance with off the shelf devices in favourable anatomies.

Early Experience of Endovascular Repair of Post-dissection Aneurysms Involving the Thoraco-abdominal Aorta and the Arch.

OBJECTIVES: Outcomes are reported in management of post-dissection aneurysms involving the aortic arch and/or thoraco-abdominal segment (TAAA) treated with fenestrated and branched (complex) endografts. METHODS: This report includes all patients with chronic post-dissection aneurysms >55 mm in diameter, deemed unfit for open surgery, treated using complex endografts between October 2011 and March 2015. When appropriate, staged management strategies including left subclavian artery revascularization, thoracic endografting, dissection flap fenestration or tear enlargement, and other endovascular procedures were performed at least 3 weeks prior to definitive complex endovascular repair. The following outcome data were collected prospectively at discharge, 12 months and annually thereafter: technical success, endoleaks, target vessel patency, false lumen patency, aneurysm diameter, major and minor complications, re-interventions, and mortality. RESULTS: The cohort comprised 23 patients with a median age of 65 years. Staged procedures were performed in 14 patients (61%). Seven patients with dissections involving the arch were treated with inner branched endografts, and 16 TAAA patients were treated with fenestrated or branched endografts. The technical success rate was 71% following arch repair and 100% following TAAA repair. During early follow up, one of the arch group patients died and one in the TAAA group suffered spinal cord ischemia. The median follow up was 12 months (range 3-48), during which time one patient died of causes unrelated to aneurysm or treatment. Two early re-interventions were performed in the arch group to correct access vessel complications and there were a further two late re-interventions in the TAAA group to treat endoleaks. All target vessels (n = 72) remained patent. CONCLUSIONS: This experience indicates that complex endovascular repair of post-dissection aneurysms is a viable alternative to open repair in patients deemed unfit for open surgery. There are insufficient data to allow comparison with the outcome of open surgery in anatomically similar, but fit, patients.

Editor's Choice - Subsequent Results for Arch Aneurysm Repair with Inner Branched Endografts.

OBJECTIVES: The aim was to evaluate the current results of aortic arch aneurysm repair using inner branched endografts performed in three high volume aortic endovascular centers and to compare them to the pioneering global experience with this technology. METHODS: Included patients underwent repair of aortic arch aneurysms >55 mm in diameter using inner branched endograft technology between April 2013 and November 2014. All patients were deemed unfit for open surgery. Inner branches were designed to perfuse the brachiocephalic trunk and the left common carotid artery in all cases. A left subclavian artery (LSA) revascularization was performed prior to the arch endovascular repair. Data were collected retrospectively in an electronic database. Parameters included length of procedure, fluoroscopy time, contrast volume, technical success, presence of endoleaks, early and late complications, and mortality. RESULTS: Twenty-seven patients were included in the study. Technical success was achieved in all cases. No patients died during the 30 day post-operative period. Early neurologic events included two major strokes (7.4%) and one minor stroke (3.7%). Transient spinal cord ischemia with full recovery was observed in two patients (7.4%). Four patients (14.8%) underwent early (<30 day) re-interventions; these were for an access complication, an ischemic limb and exploration of the left ventricle through a sternotomy in two patients. During follow up (median 12 months), one patient (3.7%) died from a remote thoraco-abdominal aneurysm rupture. There were three Type 2 endoleaks (11.1%). Two re-interventions (7.4%) were performed, one to treat a Type 2 endoleak and one to treat a septic false aneurysm. A significant decrease in overall mortality was observed when comparing patients from the early experience with patients from the current report. CONCLUSIONS: The early outcomes associated with this technology are favorable. Branched endografting of aortic arch aneurysms should be considered in patients unfit for open surgery.

The impact of early pelvic and lower limb reperfusion and attentive peri-operative management on the incidence of spinal cord ischemia during thoracoabdominal aortic aneurysm endovascular repair.

OBJECTIVE/BACKGROUND: Spinal cord ischemia (SCI) is a devastating complication following endovascular thoracoabdominal aortic aneurysm (TAAA) repair. In an attempt to reduce its incidence two peri-procedural changes were implemented by the authors in January 2010: (i) all large sheaths are withdrawn from the iliac arteries immediately after deploying the central device and before cannulation and branch extension to the visceral vessels; (ii) the peri-operative protocol has been modified in an attempt to optimize oxygen delivery to the sensitive cells of the cord (aggressive blood and platelet transfusion, median arterial pressure monitoring >85 mmHg, and systematic cerebrospinal fluid drainage). METHODS: Between October 2004 and December 2013, 204 endovascular TAAA repairs were performed using custom made devices manufactured with branches and fenestrations to maintain visceral vessel perfusion. Data from all of these procedures were prospectively collected in an electronic database. Early post-operative results in patients treated before (group 1, n = 43) and after (group 2, n = 161 patients) implementation of the modified implantation and peri-operative protocols were compared. RESULTS: Patients in groups 1 and 2 had similar comorbidities (median age at repair 70.9 years [range 65.2-77.0 years]), aneurysm characteristics (median diameter 58.5 mm [range 53-65 mm]), and length of procedure (median 190 minutes [range 150-240 minutes]). The 30 day mortality rate was 11.6% in group 1 versus 5.6% in group 2 (p = .09). The SCI rate was 14.0% versus 1.2% (p < .01). If type IV TAAAs were excluded from this analysis, the SCI rate was 25.0% (6/24 patients) in group 1 versus 2.1% (2/95 patients) in group 2 (p < .01). CONCLUSION: The early restoration of arterial flow to the pelvis and lower limbs, and aggressive peri-operative management significantly reduces SCI following type I-III TAAA endovascular repair. With the use of these modified protocols, extensive TAAA endovascular repairs are associated with low rates of SCI.

Renal Outcomes Following Fenestrated and Branched Endografting.

OBJECTIVE: The purpose of this study was to analyze immediate and long-term renal outcomes (renal function and renal events) after fenestrated (FEVAR) and branched endovascular aortic aneurysm repair (BEVAR). METHODS: All FEVAR and BEVAR performed between October 2004 and October 2012 were included in this study. Post-operative acute renal failure (ARF) was defined according to the RIFLE criteria. Renal volume (calculated with a 3D workstation) and estimated glomerular filtration rate (GFR) (estimated with the Modification of Diet in Renal Disease [MDRD] formula) were evaluated before the procedure, before discharge, 12 months after, and yearly thereafter. Renal stent occlusion, dissection, fracture, stenosis, kink, renal stent related endoleak, and renal stent secondary intervention were all considered "renal composite events" and analyzed. A time to event analysis was performed for renal events and secondary renal interventions. RESULTS: 225 patients were treated with FEVAR and BEVAR. Renal target vessels (n = 427) were perfused by fenestrations (n = 374), or branches (n = 53). Median follow up was 3.1 years (2.9-3.3 years). Technical success was achieved in 95.5% of patients. Post-operative ARF was seen in 64 patients (29%). Mean total renal volume and eGFR at 1 year, 2 year, and 3 year follow up were significantly lower when compared with pre-operative levels (after BEVAR and FEVAR); the decrease at 3 years was 14.8% (6.7%; 22.2%) (p = .0006) for total renal volume and 14.3% (3.1%; 24.3%) (p = .02) for eGFR. The 30 day and 5 year freedom from renal composite event was 98.6% (95.8-99.6%) and 84.5% (76.5-89.9%) after FEVAR and BEVAR (NS). The 30 day and 5 year freedom from renal occlusion was 99.5% (96.7-99.9%) and 94.4% (89.3-97.1%) after FEVAR and BEVAR (NS). CONCLUSION: FEVAR and BEVAR are durable options for the treatment of complex aortic aneurysms and are associated with low renal morbidity, without differences between devices types. The clinical impact of decreasing renal volume over time in these patients is yet to be fully understood.

Benefits of Completion 3D Angiography Associated with Contrast Enhanced Ultrasound to Assess Technical Success after EVAR.

OBJECTIVES: This study evaluated a new strategy to assess technical success after standard and complex endovascular aortic repair (EVAR), combining completion contrast enhanced cone beam computed tomography (ceCBCT) and post-operative contrast enhanced ultrasound (CEUS). METHODS: Patients treated with bifurcated or fenestrated and branched endografts in the hybrid room during the study period were included. From December 2012 to July 2013, a completion angiogram (CA) was performed at the end of the procedure, and computed tomography angiography (CTA) before discharge (group 1). From October 2013 to April 2014, a completion ceCBCT was performed, followed by CEUS during the 30 day post-operative period (group 2). The rate of peri-operative events (type I or III endoleaks, kinks, occlusion of target vessels), need for additional procedures or early secondary procedures, total radiation exposure (mSv), and total volume of contrast medium injected were compared. RESULTS: Seventy-nine patients were included in group 1 and 54 in group 2. Peri-operative event rates were respectively 8.9% (n = 7) and 33.3% (n = 18) (p = .001). Additional procedures were performed in seven patients (8.9%) in group 1 versus 17 (31.5%) in group 2 (p = .001). Two early secondary procedures were performed in group 2 (3.7%), and three (3.8%) in group 1 (p = .978). Median radiation exposure due to CBCT was 7 Gy cm(2) (5.25-8) (36%, 27%, and 9% of the total procedure exposure, respectively for bifurcated, fenestrated, and branched endografts). CEUS did not diagnose endoleaks or any adverse events not diagnosed by ceCBCT. Overall radiation and volume of contrast injected during the patient hospital stay in groups 1 and 2 were 34 (25.8-47.3) and 11 (5-20.5) mSv, and 184 (150-240) and 91 (70-132.8) mL respectively (reduction of 68% and 50%, p < .001). CONCLUSIONS: Completion ceCBCT is achievable in routine practice to assess technical success after EVAR. Strategies to evaluate technical success combining ceCBCT and CEUS can reduce total in hospital radiation exposure and contrast medium volume injection.

Total endovascular treatment of an aortic arch aneurysm in a patient with a mechanical aortic valve.

INTRODUCTION: Endovascular repair of aortic arch aneurysms using an inner-branched device is a new treatment option for patients unfit for open surgery. There are many anatomical restrictions, such as the presence of a mechanical aortic valve that can contraindicate this complete endovascular approach. REPORT: A new delivery system to overcome this issue has been developed. This new system was used to treat an aortic arch aneurysm 77 mm in diameter in a 37-year-old patient with Marfan's syndrome. The patient was considered to be at major risk for open surgery because of severe respiratory insufficiency following a second sternotomy. DISCUSSION: Total endovascular arch aneurysm repair is no longer contraindicated in patients with a mechanical aortic valve.

Feasibility of performing treadmill walking test for patients with peripheral arterial occlusive disease by the advanced practice nurses.

AIM: The treadmill walking test with post-exercise pressure measurement can be used as a diagnostic test and could classify peripheral arterial disease of the lower limbs. It can also exclude the diagnosis allowing to raise the possibility of differential diagnoses. In this study, we assessed the feasibility of performing treadmill test by advanced practice nurse to assess suspected lower extremity peripheral artery disease patients. DESIGN AND METHOD: This is a longitudinal monocentric study to assess the feasibility of a treadmill walking test performed by an advanced practice nurse. The primary endpoint was the number of tests performed during this period. The secondary objectives were to evaluate the reasons for requesting the test, the main results obtained in terms of the test's contribution and diagnoses, and patients' clinical characteristics. RESULTS: From February to May 2023, amongst 31 patients who underwent the treadmill walking test, 4 tests were able to rule out peripheral arterial disease and to detect differential diagnoses. For the remaining 27 patients, 4 had stage IIa of the Leriche classification, 23 had stage IIb, 2 of which were associated with a narrow lumbar spine. In contrast to the usual report, the APN's report on the walking test included an identification of cardiovascular risk factors, as well as a possible medical reorientation linked to the correction of a detected cardiovascular risk factor. CONCLUSION: The treadmill walking test can be performed by an advanced practice nurse. He/She added a comprehensive/global patient management, with the detection of cardiovascular risk factors. This new profession led to an increase in the number of tests performed of more than 50% over the period and reduced the time to access the test.

[Management of Stent-graft migration with obstruction of supra-aortic vessel during an endovascular procedure for aortic isthmus rupture]. / Migration d'endoprothèse thoracique avec occlusion des troncs supra-aortiques en per-procédure pour rupture isthmique ; prise en charge.

The endovascular approach is widely used in the management of aortic isthmic rupture. Even if it remains less invasive than conventional surgery, a life-threatening complications are possible. We report the case of a young female patient presenting a stent-graft migration during the deployment with total obstruction of the supra-aortic vessels. We describe the therapeutic management with a cerebral rescue procedure followed by a delayed surgical repair.

Centerline is not as accurate as outer curvature length to estimate thoracic endograft length.

BACKGROUND: To assess the accuracy of the aortic outer curvature length for thoracic endograft planning. METHODS: Seventy-four patients (58 men, 66.4 ± 14 years) who underwent thoracic endovascular aortic repair between 2009 and 2011 treated with a Cook Medical endograft were enrolled in this retrospective study. Immediate postoperative CT scans were analysed using EndoSize software. Three vessel lengths were computed between two fixed landmarks placed at each end of the endograft: the straightline (axial) length, the centerline length and the outer curvature length. A tortuosity index was defined as the ratio of the centerline length/straightline length. A Student t test and a Pearson correlation coefficient were used to examine the results. RESULTS: We found a significant difference between the centerline length (135.4 ± 24 mm) and that of the endograft (160 ± 29 mm) (p < .0001). This difference correlates with the tortuosity index (r = .818, p < .0001), the endograft length (r = .587, p < .0001), and the diameter of the endograft (r = .53, p < .0001). However, the outer curvature length (161.3 ± 29 mm) and the endograft length (160 ± 29 mm) were similar (p = .792). CONCLUSION: The outer curvature length more accurately reflects that of the deployed endograft and may prove more accurate than centerlines in planning thoracic endografts.

Technical note and results in the management of anatomical variants of renal vascularisation during endovascular aneurysm repair.

INTRODUCTION: The revascularisation of large (>3 mm) renal arteries emerging from the proximal sealing zone or off the aneurismal wall can be challenging during endovascular aortic aneurysm repair. In this article, we describe various endovascular techniques using custom-made endografts to treat these complex variant anatomies. CASES: Nine patients deemed unfit for open repair with unusual renal vascularisation associated with aortic aneurysms were treated by endovascular means. After three-dimensional (3D) reconstructions on a dedicated workstation, custom-made devices were designed and manufactured. The revascularisation of multiple renal arteries and aberrant origins of renal arteries, associated or not with pelvic kidney or horseshoe kidney, was managed using fenestrated and branched endografts. RESULTS: All target vessels were patent on computed tomography (CT) scan and contrast-enhanced ultrasound evaluation before discharge as well as on the 6-month follow-up. One patient presented a decrease of postoperative glomerular filtration rate over 30% but did not require dialysis. No sac enlargement was depicted, and no reintervention was performed during follow-up. Three type 2 endoleaks were diagnosed. CONCLUSION: Endovascular treatment with fenestrated and branched endografts should be considered in challenging renal artery anatomies in patients unfit for open repair.

Culture-dependent and culture-independent assessment of bacteria in the apple phyllosphere.

AIMS: Bacterial communities in the apple phyllosphere were examined quantitatively and qualitatively by applying culture-dependent and culture-independent methods. METHODS AND RESULTS: Populations estimated by viewing cells stained with 4',6-diamidino-2-phenylindole generally were at least 100-1000 times greater than populations estimated by culturing on tryptic soy agar (TSA). Of the 44 operational taxonomic units (OTUs; cut-off threshold of 97%) detected in total, five bacterial orders containing 23 OTUs were identified by culturing on TSA, whereas nine orders containing 33 OTUs were identified by 16S rRNA gene cloning of DNA extracted from apple leaf surfaces. Twelve of the 44 OTUs were shared between cultured isolates and 16S rRNA gene clones and included the orders Burkholderiales, Pseudomonadales, Rhizobiales and Sphingomonadales. Three OTUs within the genus Sphingomonas accounted for 40% of isolates and 68% of clones. The Actinomycetales were found only among isolates, whereas the Bacteroidales, Enterobacteriales, Myxococales and Sphingobacteriales were represented in the 16S rRNA gene clone libraries but were absent among isolates. CONCLUSIONS: Culture-independent methods revealed greater numbers and greater richness of bacteria on apple leaves than found by culturing. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study to directly compare culture-dependent and independent approaches for assessing bacterial communities in the phyllosphere. The biases introduced by different methods will have a significant impact on studies related to phyllosphere ecology, biological control of plant diseases, reservoirs of antibiotic resistance genes and food safety.

Exposure to ethylene oxide at work increases sister chromatid exchanges in human peripheral lymphocytes.

Sister chromatid exchange rates increased significantly in the peripheral lymphocytes of a small group of hospital workers exposed to ethylene oxide for as little as 3.6 minutes per day regularly over a period of months. Results based on breathing zone exposure and task frequency estimates over a 6-month period for 14 workers suggest that sister chromatid exchanges are a sensitive indicator of exposure and that cumulative dose and dose rate are important predictors of sister chromatid exchange response.

Evaluation of a new imaging software for aortic endograft planning.

OBJECTIVE: The aim of this study was to evaluate a new 3D Workstation workflow (EVAR Assist, Advantage Windows, GE Healthcare, Chalfont, UK) (EA-AW) designed to simplify complex EVAR planning. PATIENTS AND METHODS: All pre-operative computed tomography (CT) scans of patients who underwent repair at our institution of a complex aortic aneurysm using fenestrated endovascular repair (f-EVAR) between January and September 2014, were reviewed. For each patient, imaging analysis (12 measures: aortic diameters and length and "clock position" of visceral artery) was performed on two different workstations: Aquarius (TeraRecon, San Mateo, CA, USA) and EA-AW. According to a standardized protocol, three endovascular surgeons experienced in aortic endograft planning, performed image analyses and data collection independently. We analyzed an internal assessment between observers (on the Aquarius 3DWS) and an external assessment comparing these results with the planning center (PC) data used to custom the fenestrated endograft of the patients enrolled in this study. Finally, we compared both 3DWS data to determine the accuracy and the reproducibility. A p-value < .05 was considered as statistically significant. Complete agreement between operators was defined as 1.0. RESULTS: Intra- and inter-observer variability (interclass correlation coefficients - ICC: 0.81-.091) was very low and confirmed the reliability of our planners. The ICC comparison between EA-AW and Aquarius was excellent (> 0.8 for both), thus confirming the reproducibility and reliability of the new EA-AW application. Aortic and iliac necks diameters and lengths were similarly reported with both workstations. In our study, the mean difference in distance and orientation evaluation of target vessels evaluated by the two workstations was marginal and has no impact on clinical practice in term of device manufacturing. CONCLUSIONS: We showed that complex EVAR planning can be performed with this new dedicated 3D workstation workflow with a good reproducibility.

Acute pericardial distension in pigs: effect of fluid conductance on body surface electrocardiogram QRS size.

OBJECTIVES: Pericardial effusion has long been associated with low voltage of the surface electrocardiogram and its clinical utility is well known. The cause of this reduced QRS voltage has usually been attributed to short circuiting of the impulses by the pericardial fluid, but its precise mechanism has not been clearly elucidated. Therefore, we investigated this phenomenon by instilling various fluids with different resistances in increasing volumes into the pericardial space to finally produce acute cardiac tamponade. METHODS: Acute cardiac tamponade was produced 65 times in 25 closed chest pigs with a mean weight of 57(SEM 1.2) kg. A sufficient quantity (mean = 200 ml) of plasma, saline, blood, and blood with varying packed cell volume was introduced into the pericardial space in 60 ml increments to decrease systemic and pulmonary pressures to 50% of control to produce cardiac tamponade. At that point intrapericardial pressure had increased to 15-20 mm Hg. Resistivity values for the instilled fluids are 150 omega-cm for blood, 60 omega-cm for plasma, and 50 omega-cm for saline. RESULTS: Mean limb and precordial lead QRS voltage fell significantly, with no significant differences among these fluids. Electrocardiograph recordings from a unipolar electrode catheter in the right ventricle showed an increase in R wave voltage, but body surface recordings of stimuli introduced into the right atrium via a bipolar electrode catheter showed no amplitude change. CONCLUSIONS: In considering possibilities such as internal shunting of cardiac currents by intrapericardial fluid, distance of the heart from body surface electrodes, and change in cardiac position, the results are best explained by a reduction of cardiac volume and size during cardiac tamponade. This conclusion confirms Brody's hypothesis.

Current and future perspectives in the repair of aneurysms involving the aortic arch.

The repair of aneurysms involving the aortic arch is technically and physiologically demanding. Historically, these aneurysms have been treated using open surgical techniques that require cardiopulmonary bypass and deep hypothermic circulatory arrest. Many patients have been deemed "untreatable" and among those selected for surgery there are reported risks of death in 2% to 16.5% and stroke rates ranging from 2% to 18%. "Hybrid arch repair" combines one of a number of open surgical procedures (to secure a proximal landing zone for an endograft) with subsequent or immediate placement of an endograft in the arch and descending aorta. Although this concept is described as "minimally invasive" because it avoids aortic cross-clamping and hypothermic circulatory arrest, the morbidity and mortality rates remain considerable (mortality 0% to 15%, stroke 0% to 11%). Ongoing development of endograft technology has enabled total endovascular repair of complex aortic aneurysms involving the visceral segment, using fenestrated and branched endografts. Encouraging early results in this anatomy have inspired extension of the concept to include the aortic arch and great vessels. These strategies can be considered in patients generally at high-risk for the conventional procedures. However, the endeavour is at an early stage of its development and the arch poses unique challenges including the potential for stroke, angulation of the arch and the great vessel ostia to the arch, extremely high volume flow, three-dimensional pulsation and rotation with the cardiac cycle and the proximity of the aortic valve and coronary arteries.

Automated image analysis of live/dead staining of the fungus Aureobasidium pullulans on microscope slides and leaf surfaces.

An image analysis program and protocol for the identification and enumeration of live versus dead cells of the yeast-like fungus Aureobasidium pullulans was developed for both populations on microscope slides and leaf surfaces. Live cells took up CellTracker Blue, while nonviable cells stained with DEAD Red. Image analysis macro programs running under Optimas software were used to acquire images and to differentiate and enumerate viable from nonviable cells. The software was capable of discriminating green as a third parameter for identification and quantification of green fluorescent protein-expressing cells in a wild-type population.

Expression of green fluorescent protein in Aureobasidium pullulans and quantification of the fungus on leaf surfaces.

A red-shifted, mutated form of the jelly-fish green fluorescent protein (GFP) under control of a TEF promoter was expressed at high levels in the filamentous fungus Aureobasidium pullulans. In the three transformants studied, all morphotypes of the fungus, including pigmented chlamydospores, expressed GFP and fluoresced brightly. Confocal microscopy showed that the intra-cellular distribution of GFP was nonuniform. When applied to leaf surfaces, the transformants were readily visible and amenable to quantification by image analysis. Thus, GFP expression, together with quantitative image analysis, may provide a powerful method for ecological studies of plant-microbe relationships in nature.

Parameter variability and the interpretation of physiologically based pharmacokinetic modeling results.

For the past several years we have been working with models of benzene distribution and metabolism, principally in the rat, but more recently in humans. Our biologically related objectives have been primarily to assist our laboratory-based colleagues in their quest for understanding of the mechanisms by which benzene exerts its toxic action. A secondary goal has been to develop or adapt models useful in risk assessment applications. We have also had methodological goals that relate to applications of sensitivity analysis on the one hand, but more fundamentally to the connection between experimental data and model structure and parameterization. This paper presents an overview of our work in these areas.