Effects of the herbicide metolachlor and pond drying on growth and development of wood frog tadpoles (Lithobates sylvaticus)

Pesticides and climate change are both thought to contribute to the global amphibian decline, yet their combined effects are still poorly understood. Metolachlor is a widespread herbicide applied across North America, but little is known about its effects on amphibians. Here, we used a replicated mesocosm experimental design with different levels of drying (i.e., no drying, medium and rapid drying) and metolachlor concentrations (0, 0.8, 8 and 80 µg/L) to assess their respective and combined effects on wood frog (Lithobates sylvaticus) larvae throughout metamorphosis. Metolachlor had no significant effect on survival and development of tadpoles. However, metolachlor significantly interacted with drying levels to reduce growth of tadpoles, which was mainly due to a difference detected among metolachlor concentrations under the rapid drying treatment. Drying also directly reduced growth and body mass at metamorphosis. Our results suggest that environmental stressors, such as drying, should be considered in toxicological experiments to provide relevant exposure conditions to pesticides for ephemeral pond species in the context of global climate change.

Cryo-EM reveals an unprecedented binding site for NaV1.7 inhibitors enabling rational design of potent hybrid inhibitors

The voltage-gated sodium (Na_V) channel Na_V1.7 has been identified as a potential novel analgesic target due to its involvement in human pain syndromes. However, clinically available Na_V channel blocking drugs are not selective among the nine Na_V channel subtypes, Na_V1.1-Na_V1.9. Moreover, the two currently known classes of Na_V1.7 subtype-selective inhibitors (aryl- and acylsulfonamides) have undesirable characteristics that may limit their development. To this point understanding of the structure-activity relationships of the acylsulfonamide class of Na_V1.7 inhibitors, exemplified by the clinical development candidate GDC-0310, has been based solely on a single co-crystal structure of an arylsulfonamide inhibitor bound to voltage-sensing domain 4 (VSD4). To advance inhibitor design targeting the Na_V1.7 channel, we pursued high-resolution ligand-bound Na_V1.7-VSD4 structures using cryogenic electron microscopy (cryo-EM). Here, we report that GDC-0310 engages the Na_V1.7-VSD4 through an unexpected binding mode orthogonal to the arylsulfonamide inhibitor class binding pose, which identifies a previously unknown ligand binding site in Na_V channels. This finding enabled the design of a novel hybrid inhibitor series that bridges the aryl- and acylsulfonamide binding pockets and allows for the generation of molecules with substantially differentiated structures and properties. Overall, our study highlights the power of cryo-EM methods to pursue challenging drug targets using iterative and high-resolution structure-guided inhibitor design This work also underscores an important role of the membrane bilayer in the optimization of selective Na_V channel modulators targeting VSD4.

Effects of a Neonicotinoid Insecticide and Population Density on Behavior and Development of Wood Frogs (Rana sylvatica)

Amphibians have been facing global declines over the last decades from direct and indirect effects of anthropogenic activities. A contributor to declines is waterway contamination from agricultural runoffs of pesticides such as neonicotinoids. Beyond direct and indirect effects of the pesticide, few studies have investigated the possible interactions between neonicotinoids and natural environmental stressors across larval development, which could alter the strength and direction of observed neonicotinoid effects. The present study used a fully crossed design to investigate how a concentration of imidacloprid (a neonicotinoid; 10 µg/L) measured in surface waters interacted with low and high population densities (0.33 and 1 tadpole/L, respectively), an important environmental stressor, to influence behavior and development across metamorphosis in wood frogs (Rana sylvatica), known to breed in agricultural landscapes. Behaviors were measured in the absence and presence of predation cues using open-field tests at three distinct developmental stages, up to the metamorph stage. We found that imidacloprid did not interact with population density or independently affect behaviors in the absence of predation cues. However, individuals raised at high density compared with low density were more active at an early developmental stage but less active at metamorphic climax. Furthermore, both density and imidacloprid independently decreased the natural freezing response of tadpoles to predation cues. Finally, we found that distance traveled in the open-field test was weakly repeatable between aquatic stages but not repeatable across metamorphosis, a pattern that was not affected by treatments. The present study provides novel insights on the ecotoxicology of imidacloprid in the presence of a natural stressor, highlighting the importance of including behavioral assays and natural stressors in studies of amphibian ecotoxicology. Environ Toxicol Chem 2022;41:2968-2980. © 2022 SETAC.

Discovery of Acyl-sulfonamide Nav1.7 Inhibitors GDC-0276 and GDC-0310

Nav1.7 is an extensively investigated target for pain with a strong genetic link in humans, yet in spite of this effort, it remains challenging to identify efficacious, selective, and safe inhibitors. Here, we disclose the discovery and preclinical profile of GDC-0276 (1) and GDC-0310 (2), selective Nav1.7 inhibitors that have completed Phase 1 trials. Our initial search focused on close-in analogues to early compound 3. This resulted in the discovery of GDC-0276 (1), which possessed improved metabolic stability and an acceptable overall pharmacokinetics profile. To further derisk the predicted human pharmacokinetics and enable QD dosing, additional optimization of the scaffold was conducted, resulting in the discovery of a novel series of N-benzyl piperidine Nav1.7 inhibitors. Improvement of the metabolic stability by blocking the labile benzylic position led to the discovery of GDC-0310 (2), which possesses improved Nav selectivity and pharmacokinetic profile over 1.

Battling Btk Mutants With Noncovalent Inhibitors That Overcome Cys481 and Thr474 Mutations

The Bruton's tyrosine kinase (Btk) inhibitor ibrutinib has shown impressive clinical efficacy in a range of B-cell malignancies. However, acquired resistance has emerged, and second generation therapies are now being sought. Ibrutinib is a covalent, irreversible inhibitor that modifies Cys481 in the ATP binding site of Btk and renders the enzyme inactive, thereby blocking B-cell receptor signal transduction. Not surprisingly, Cys481 is the most commonly mutated Btk residue in cases of acquired resistance to ibrutinib. Mutations at other sites, including Thr474, a gatekeeper residue, have also been detected. Herein, we describe noncovalent Btk inhibitors that differ from covalent inhibitors like ibrutinib in that they do not interact with Cys481, they potently inhibit the ibrutinib-resistant Btk C481S mutant in vitro and in cells, and they are exquisitely selective for Btk. Noncovalent inhibitors such as GNE-431 also show excellent potency against the C481R, T474I, and T474M mutants. X-ray crystallographic analysis of Btk provides insight into the unique mode of binding of these inhibitors that explains their high selectivity for Btk and their retained activity against mutant forms of Btk. This class of noncovalent Btk inhibitors may provide a treatment option to patients, especially those who have acquired resistance to ibrutinib by mutation of Cys481 or Thr474.

Design and Development of a Series of Potent and Selective Type II Inhibitors of CDK8

Using Sorafenib as a starting point, a series of potent and selective inhibitors of CDK8 was developed. When cocrystallized with CDK8 and cyclin C, these compounds exhibit a Type-II (DMG-out) binding mode.

Development of a Potent, Specific CDK8 Kinase Inhibitor Which Phenocopies CDK8/19 Knockout Cells

Beginning with promiscuous COT inhibitors, which were found to inhibit CDK8, a series of 6-aza-benzothiophene containing compounds were developed into potent, selective CDK8 inhibitors. When cocrystallized with CDK8 and cyclin C, these compounds exhibit an unusual binding mode, making a single hydrogen bond to the hinge residue A100, a second to K252, and a key cation-π interaction with R356. Structure-based drug design resulted in tool compounds 13 and 32, which are highly potent, kinase selective, permeable compounds with a free fraction >2% and no measurable efflux. Despite these attractive properties, these compounds exhibit weak antiproliferative activity in the HCT-116 colon cancer cell line. Further examination of the activity of 32 in this cell line revealed that the compound reduced phosphorylation of the known CDK8 substrate STAT1 in a manner identical to a CDK8 knockout clone, illustrating the complex effects of inhibition of CDK8 kinase activity in proliferation in these cells.

Intralocus sexual conflict, adaptive sex allocation, and the heritability of fitness

Intralocus sexual conflict arises when selection favours alternative fitness optima in males and females. Unresolved conflict can create negative between-sex genetic correlations for fitness, such that high-fitness parents produce high-fitness progeny of their same sex, but low-fitness progeny of the opposite sex. This cost of sexual conflict could be mitigated if high-fitness parents bias sex allocation to produce more offspring of their same sex. Previous studies of the brown anole lizard (Anolis sagrei) show that viability selection on body size is sexually antagonistic, favouring large males and smaller females. However, sexual conflict over body size may be partially mitigated by adaptive sex allocation: large males sire more sons than daughters, whereas small males sire more daughters than sons. We explored the evolutionary implications of these phenomena by assessing the additive genetic (co)variance of fitness within and between sexes in a wild population. We measured two components of fitness: viability of adults over the breeding season, and the number of their progeny that survived to sexual maturity, which includes components of parental reproductive success and offspring viability (RS(V) ). Viability of parents was not correlated with adult viability of their sons or daughters. RS(V) was positively correlated between sires and their offspring, but not between dams and their offspring. Neither component of fitness was significantly heritable, and neither exhibited negative between-sex genetic correlations that would indicate unresolved sexual conflict. Rather, our results are more consistent with predictions regarding adaptive sex allocation in that, as the number of sons produced by a sire increased, the adult viability of his male progeny increased.

Structure-Guided Rescaffolding of Selective Antagonists of BCL-XL

Because of the promise of BCL-2 antagonists in combating chronic lymphocytic leukemia (CLL) and non-Hodgkin's lymphoma (NHL), interest in additional selective antagonists of antiapoptotic proteins has grown. Beginning with a series of selective, potent BCL-XL antagonists containing an undesirable hydrazone functionality, in silico design and X-ray crystallography were utilized to develop alternative scaffolds that retained the selectivity and potency of the starting compounds.

A hit to lead discovery of novel N-methylated imidazolo-, pyrrolo-, and pyrazolo-pyrimidines as potent and selective mTOR inhibitors

A series of N-7-methyl-imidazolopyrimidine inhibitors of the mTOR kinase have been designed and prepared, based on the hypothesis that the N-7-methyl substituent on imidazolopyrimidine would impart selectivity for mTOR over the related PI3Kα and δ kinases. The corresponding N-Me substituted pyrrolo[3,2-d]pyrimidines and pyrazolo[4,3-d]pyrimidines also show potent mTOR inhibition with selectivity toward both PI3α and δ kinases. The most potent compound synthesized is pyrazolo[4,3-d]pyrimidine 21c. Compound 21c shows a Ki of 2 nM against mTOR inhibition, remarkable selectivity (>2900×) over PI3 kinases, and excellent potency in cell-based assays.

Discovery and Biological Profiling of Potent and Selective mTOR Inhibitor GDC-0349

Aberrant activation of the PI3K-Akt-mTOR signaling pathway has been observed in human tumors and tumor cell lines, indicating that these protein kinases may be attractive therapeutic targets for treating cancer. Optimization of advanced lead 1 culminated in the discovery of clinical development candidate 8h, GDC-0349, a potent and selective ATP-competitive inhibitor of mTOR. GDC-0349 demonstrates pathway modulation and dose-dependent efficacy in mouse xenograft cancer models.

Potent, selective, and orally bioavailable inhibitors of the mammalian target of rapamycin kinase domain exhibiting single agent antiproliferative activity

Selective inhibitors of mammalian target of rapamycin (mTOR) kinase based upon saturated heterocycles fused to a pyrimidine core were designed and synthesized. Each series produced compounds with K(i) < 10 nM for the mTOR kinase and >500-fold selectivity over closely related PI3 kinases. This potency translated into strong pathway inhibition, as measured by phosphorylation of mTOR substrate proteins and antiproliferative activity in cell lines with a constitutively active PI3K pathway. Two compounds exhibiting suitable mouse PK were profiled in in vivo tumor models and were shown to suppress mTORC1 and mTORC2 signaling for over 12 h when dosed orally. Both compounds were additionally shown to suppress tumor growth in vivo in a PC3 prostate cancer model over a 14 day study.

Aortic debranching from the ascending aorta: a novel surgical approach for extended TAAA and chronic type B dissections in high risk patients

AIM

Extend thoraco-abdominal aortic aneurysms (TAAA) involving arch vessels and the visceral arteries remains a challenging operation when affecting high risk patients (HRP). Recently, hybrid surgery has gained popularity for HRP. The conventional surgical repair is the gold standard for low risk patients with previous mortality from 6% to 15% in thoracic aneurysms up to 30% in thoracic type B dissections. The risk of paraplegia is 3% to 15%. Without repair the outcome is poor with only 35% of patient's survival at two years after diagnosis. The total endovascular technique is not widespread used because of its very time-consuming, needs training, and procedure planning with high radiation exposure. Only few centers in the world perform it. In order to reduce the morbidity a novel approach is proposed, with an aortic debranching from the ascending aorta.

METHODS

Nine patients (two females) aged between 53 and 81 years, with high risk factors for surgery, were offered this hybrid technique from March 2004 to July 2009. Eight patients presented with a TAAA and one type a B chronic dissection. A staged hybrid operation started by a debranching of the aorta from a median sternotomy to supra-aortic vessels and visceral arteries, followed by the second stage one-two weeks later, with an extended stent grafting. This attitude avoids CPB and aortic cross clamping. The surgical approach is a median sternotomy combined to mid upper laparotomy associated to pericardial and diaphragm division. It is well tolerated even in elderly patients and allows easy access to celiac axis (CA), superior mesenteric artery (SMA), right renal artery (RRA). Access to the left renal artery is more difficult and may be benefit from a combinated stent grafting and bypass according to the VORTEC technique described by Lachat M, or an extra-anatomic bypass. Rerouting the visceral arteries is done from the ascending aorta with a partial clamping on an undiseased implantation site, offering à good anterograde high flow. Combined bypass to supraaortic vessels is associated when needed.

RESULTS

There was no intraoperative mortality. One patient died during 30D period from cardiac failure and another on the early follow up from a pancreatic fistula. The complications: one stroke (11.1%); one cardiac failure (11.1%); one renal failure (11.1%), one pancreatic fistula (11.1%), one non-infected retrostrenal collection (11.1%). No paraplegia, limb ischemia or aortic fistula were detected. No stent-graft related complication was retrieved, the bypass patency was 77.7 at four-year survival.

CONCLUSION

Our early and mid term results are promising and similarly to other series. This new approach for rerouting the supraaortic and visceral arteries before stent grafting in extended TAAA, lowers the surgical injury and is particularly designed for HRP who cannot benefit from conventional surgery under CPB. Larger series and longer follow-up are needed.

Retrograde type A aortic dissections after endovascular stent-graft placement for type B dissection

Thoracic endovascular aortic repair (TEVAR) has emerged as promising and a less invasive alternative to open surgery for high risk patients (HRP) with type B thoracic aortic dissection (TAD). One of the most serious complication of TEVAR is the retrograde type A TAD (rATAD). This review will focus on an interesting rATAD case and will review the literature, regarding the true incidence, mortality, causes, diagnosis, complications and management of rATAD. Until the development of a specific device for TAD, efforts must be made for better patient and device selection, careful and precise instrumentation, and life-long surveillance to minimize this lethal complication.

Temporal approach: a good way to provide cerebral protection for proximal carotid stenosis, the last chance for trackability in CAS

AIM

The aim of this study was to evaluate the usefulness of the temporal approach during coronary artery stenosis (CAS) to overcome tortuosity in case of difficult arch anatomy or tortuous common carotid artery, and to provide cerebral protection of proximal lesions of the supra-aortic trunks during stenting.

METHODS

The superficial temporal artery is exposed through a small incision right in front of the ear and is cannulated. A guidewire is used to descend in the external and common carotid artery and in the arch if needed. Between the end of March 2007 and May 2008 9 patients were treated with the temporal approach: in 5 cases of stenosis of the internal carotid artery with difficult arch anatomy to obtain a through and through guide from the temporal to the femoral artery, in 3 of the supra-aortic trunks to obtain cerebral protection during the procedure and in one case of tandem lesion of the left common and internal carotid artery.

RESULTS

The procedure was successful in all 9 cases and there were no complications.

CONCLUSIONS

The temporal approach proved to be feasible and at low risk; it represents a new possibility to increase the feasibility of carotid artery stenting in patients with difficult anatomy but, above all, it is a good way to obtain cerebral protection during endovascular treatment of proximal lesions of the supra-aortic vessels.

Setting up of a multicentric European registry dealing with type B dissections in chronic and acute phases with thoracic EndoFit devices

AIM

This registry aims at evaluating the use and efficacy of the EndoFit stent graft (LeMaitre Vascular, Burlington MA, USA) for the treatment of acute and chronic aortic type B dissections.

METHODS

Indications for treatment are: recurrent pain, persistent hypertension, serious organ malperfusion in patients with acute or subacute type B aortic dissection and progression of aneurysm size despite maximal medical therapy in patient with chronic type B dissection. Exclusion criteria are: age under 18 years old, pregnancy, coagulopathy or bleeding disorders, connective tissue disease. Straight or tapered EndoFit stent graft will be used in acute or chronical dissection respectively.

RESULTS

The primary endpoint is the assessment of the safety and the efficacy of the EndoFit Thoracic Endoluminal Stent Graft in the exclusion of the thoracic aortic false lumen in acute and chronic type B aortic dissections. The assessment includes: technical success, thrombosis of the thoracic false lumen at 6 months, rate of aorto-enteric, aorto-esophageal and aorto-bronchial fistula, serious adverse events including death, stroke, paraplegia, myocardial infarction, multi-organ failure and renal insufficiency. Secondary endpoints are: the technical feasibility of device implantation in 2 different shapes (straight for acute dissection and tapered for chronic dissection), the technical feasibility of endovascular placement of tapered grafts in vessels of different size and shape, the integrity of the device fabric and wire structure, the occurrence of device migration, the patient's neurological, cardiac and cardiovascular status, the blood flow supply to abdominal and visceral organs arteries and any secondary intervention including stentgraft extension, coiling or surgical conversion. One hundred patients enrolled have been defined to allow reliable findings and results.

CONCLUSION

The DEDICATED is the first prospective data collection registry focusing on the role of tapered stentgrafts in chronic aortic dissection and their efficacy in excluding the dissected thoracic false lumen.

Identification of proximal landing zone limit for proper deployment of aortic arch stentgraft after supra-aortic great vessels transposition

The proper identification of the proximal landing zone prior to aortic stentgraft deployment is a key step that impacts the global outcome of the procedure. We report an intraoperative technique during total aortic arch transposition that facilitates subsequent endovascular arch exclusion thanks to a reliable radio-opaque marker. In patients who require an endovascular exclusion of the aortic arch, a total arch transposition can be performed through a median sternotomy prior to stentgraft deployment. During the surgical stage, a radio-opaque thread is pull out of a surgical sponge pad, looped around the ascending aorta just distal to the ostium of the aorto-innominate bypass and fixed in place by means of metal clips. The technique we describe increases the accuracy of stentgraft deployment in the ascending aorta after total arch transposition. It will potentially improve the outcome.

Novel technique: staged hybrid surgical and endovascular treatment of acute Type A aortic dissections with aortic arch involvement

AIM

The standard approach for treating acute Type A aortic dissections (TAD) is replacement of the ascending aorta utilizing hypothermic circulatory arrest (HCA), which is associated with significant morbidity and frequently leaves a residual aortic arch dissection. We describe a staged surgical and endovascular technique of ascending aorta replacement and simultaneous aorto-innominate artery bypass without HCA, followed 4 weeks later by carotid-carotid bypass and endovascular exclusion of the remaining arch dissection with a thoracic endograft.

METHODS

From December 2004 to December 2005, 5 consecutive patients (mean age 58 +/- 6.9 years) with TADs underwent the staged procedure. All patients underwent replacement of the ascending aorta and aorto-innominate bypass. Two patients subsequently underwent the second endovascular stage. In one patient the aortic false lumen completely thrombosed following the first surgical stage and two patients are currently awaiting the endovascular stage.

RESULTS

There were no major adverse events (death, cerebrovascular accident or paraplegia) following the first surgical stage. One patient suffered a transient minor stroke. The 2 patients who underwent the second endovascular stage showed no immediate adverse events. Postoperative CT scans have demonstrated that the false channel was excluded from the aortic arch down to the distal end of the endograft in the descending aorta in each case, but became patent further downstream.

CONCLUSIONS

This procedure appears safe and feasible. It may allow for a more definitive treatment of TADs than the standard surgical approach. It can be adapted by low volume centers, surgeons untrained in aortic arch repair, and in high risk patients.

Great Vessel Management for Endovascular Exclusion of Aortic Arch Aneurysms and Dissections

OBJECTIVES

To evaluate a recent approach for the endovascular repair of thoracic aortic aneurysms and dissections involving the aortic arch in high risk patients (HRP).

METHODS

Amongst 102 thoracic aortic aneurysms and dissections, we treated 25 patients for aortic arch endovascular exclusion after transposition of the great vessels, of which 14 (56%) had thoracic aortic arch aneurysms and 11 type A and B chronic aortic dissections. Total transpositions were done in 15 cases (60%) and hemi-arch transpositions in 10. We then used Talent, Excluder and Zenith endografts in 12, seven and six cases, respectively.

RESULTS

Surgical transpositions were complicated by one minor stroke, which worsened to a major stroke (4%) after endovascular exclusion. After endovascular exclusions, two patients (8%) died from catheterization related complications. One patient had a delayed minor stroke (4%). The successful exclusion rate was 92%. During follow-up (15+/-5.8 months), one patient (4%) developed unilateral limb palsy, successfully treated by CSF drainage. The late exclusion rate remained 92%. No stent-related complications were seen.

CONCLUSIONS

Transposition of supra-aortic vessels allows the endovascular exclusion of the aortic arch in HRP. Aortic endografting after surgical transposition proved to be feasible and offers good mid-term results. Specialized surgical centers with both endovascular and surgical expertise are required to treat these patients.

Can carotid stenting registries help in determining predictors of neurological outcome?

AIM

Carotid stenting (CS) has proved to be a safe alternative to carotid endarterectomy, and subsets of patients who may benefit from carotid stents rather than surgery still need to be defined. Randomized trials and individual series are looking at predicting factors of early outcome after carotid angioplasty and stenting (CAS) that can hardly be applied to all series. We analyzed early results of the Eurocast registry and discussed the potential role of multicentric registries in determining such outcome predictors.

METHODS

The Eurocast registry is an online prospective registry on CAS that collected 897 procedures from February 2000 to December 2005 across 20 centers. Statistical analyses were performed with the univariate Fisher's exact test on CS procedures, excluding sole balloon angioplasty. Risk factors reported were hypertension, hyperlipidemia, past or current history of smoking, diabetes mellitus, obesity, cardiac disease, other vascular disease, pulmonary disease, hostile neck and renal failure. Half of patients (50.2%) had symptomatic carotid lesions. Local anesthesia (91.8%) and retrograde femoral access (95.6%) were the preferred method. Overall procedures were achieved in 98.2%, of which 84.5% were performed under cerebral protection.

RESULTS

Intraoperative neurological complications occurred in 26 (3.1%) of 824 procedures achieved. No immediate deaths were reported. The intraoperative ipsilateral stroke/death rate was 1.7%. The overall in-hospital stroke/death rate was 3.5%. Significant predictors of early neurological complications were infarctions on preoperative cerebral CT scanning, a deficient circle of Willis, a too short preoperative length of medication (7 days or less), any additional intervention (stenting and/or balloon dilatation), bradycardia and hypotension. Less reliable predictors were: age >70 years, renal failure, preoperative speech or motor deficit, postradiation stenosis, lesion on the left carotid axis and lesion on the common carotid artery.

CONCLUSIONS

This analysis confirmed that CS is a feasible and secure technique to treat carotid stenosis. However, the determination of neurological outcome predictors remains subject to further confirmation. Other patient subgroups identified in other studies (female sex, diabetics, coronary disease) should be investigated more precisely. Finally, the Eurocast analysis showed that the setting up of risk scores would be dependent on local practices, physicians' experience and would not be reproducible.

Synchronous endovascular treatment for serial tandem proximal common carotid artery and internal carotid lesions

PURPOSE

To report simultaneous endovascular repair of tandem proximal common carotid artery and internal carotid artery in a patient with complex post-radiotherapy lesions.

CASE REPORT

A 67-year-old woman with a medical history of cervical and thoracic radiotherapy and claudication, was admitted with the diagnosis of critical inferior limb ischaemia (stage III-Fontaine) and two recents episodes of amaurosis fugax of the left eye. Duplex Scan and M.R. Angiography revealed high grade stenosis of the proximal left common and internal carotid artery and a complete bilateral iliac artery occlusion. A synchronous ante- and retro-grade carotid endovascular treatment was performed in the first stage of the treatment, allowed by an open minimal cervical access under cerebral filter protection (Angio-Guard system, Cordis corp.). The post-operative period was uneventful. The patient underwent a succesful aortobifemoral reconstruction soon afterwards. At 26 months, the patient was asymptomatic. Duplex Scan confirmed a good patency of the carotid stents with normal cerebral CT Scan.

CONCLUSIONS

Serial common and internal carotid lesions appear amenable to concomitant ante- and retro-grade endovascular repair in selected patients.

Great vessels transposition and aortic arch exclusion

AIM

We describe our experience in endovascular repair of Thoracic Aortic Aneurysms and Dissections (TAAD) involving the aortic arch in high risk patients (HRP).

METHODS

Twenty-nine patients presented with TAAD involving the aortic arch and were treated by endovascular exclusion. Pathologies were as follows: atherosclerotic aneurysms of the descending thoracic aorta in 15 cases, acute Stanford type A dissections in 6 cases, Stanford type B dissections in 7 cases (1 acute), and 1 false aneurysm of the ascending aorta. Total-arch transpositions of all supra-aortic vessels (aortic debranching) to the ascending aorta were done in 11 cases throught median sternotomy. We performed carotido-carotid bypass (hemi-arch transposition) in 16 patients by cervicotomy. Secondary to surgical transpositions, we placed endovascular stentgrafts in all but 2 patients for final exclusion, the 2 remaining being planned for later exclusion. The Talent, Excluder, TAG and Zenith endografts were used in 12, 3, 1 and 4 cases respectively. Banding technique was associated in some cases.

RESULTS

All surgical transpositions were successful although 1 led to a minor stroke (1/29=3.5%), which worsened to major stroke after endovascular exclusion. Endovascular procedures were performed in all but one case (26/27=96.3%). Two patients (2/26=7.7%) died from catheterization related complications after endovascular exclusion (iliac rupture and left ventricle perforation). One patient had a delayed minor stroke (1/26=3.8%). Recirculation was found in 13.3% (2/15) of aneurysms and 27.3% of thoracic false channels. During a mean follow-up of 15.7 months (13 days to 45.5 months), 1 patient (1/26=3.8%) who had preoperative chronic pulmonary failure died at 6 months from respiratory worsening. We observed one case (3.8%) of unilateral limb palsy unrelated to cerebral ischemia, which we successfully treated by cerebrospinal fluid (CSF) drainage. No stent-related complication was seen. One new type 1 endoleak appeared at 12 months on an aneurysm, which resolved after stentgraft extension. Three thoracic dissection false channels remained patent during follow-up, of which one was retrograde originating distally in the descending aorta.

CONCLUSIONS

Secondary endovascular exclusion of thoracic aortic diseases involving the arch in HRP is made feasible thanks to the preliminary aortic debranching. Total-arch transposition may be of greater interest in case of proximal neck length uncertainty and potential embolization from the aortic arch. Mid-term results are good although patients must be followed carefully to detect aortic recirculation and enlargement.

Endovascular treatment of thoracic aortic aneurysms

Descending thoracic aortic aneurysms (TAA) and chronic dissections have high morbidity and mortality rates. For 10 years, the evolution of both imaging techniques and aortic stent-graft design has brought a new therapeutic hope for patients at high risk for surgery presenting non-ruptured or emergency cases of TAA. Our goal is to describe the endovascular technique, review its state of the art and compare its mid-term results to those of conventional surgery. We also describe surgical ways to manage complex TAA, involving the aortic arch and/or the celiac aorta, as therapeutic solutions for high risk patients for surgery with unfitted anatomy for endovascular repair. After a review of the literature dealing with the natural history, the etiology, and the surgical treatment, we describe the endovascular devices, the conventional stent-grafting technique and we detail the adjunctive procedures we used to manage complex cases. We then retrospectively report our personal 38-patient experience from October 1999 to February 2003. Thirty-three patients presented with TAA and the average age was 70 years old (35-88), while the male/female ratio was 5.3. All of them were at high risk for surgery, of which 27% required adjunctive procedures to achieve proximal and/or distal neck management. The in-hospital death rate was 9%. We reported no case of paraplegia and only 1 patient with post-operative regressive stroke (3%). All the aneurysmal sacs were successfully excluded without early endoleak. During follow-up period (mean: 2 years; 1-40 months), we observed a late death rate of 10%. All aneurysmal sac remained excluded by the endografts and no stent-graft migration was observed. No late endoleak appeared during the follow-up course, but 1 patient presented a proximal aortic enlargement, which required total transposition of the supra-aortic vessels and stent-graft extension. The endovascular repair of TAA and chronic dissections proved to be feasible and offers hopeful mid-term

RESULTS

With a very low morbidity-mortality rate, compared to surgery, the endovascular technique may represent an unquestionable therapeutic options, especially for patients at high risk for surgery. However, long-term results are needed to point out the durability of descending thoracic aortic stent-grafting. Neck management must be encouraged in order to avoid type 1 endoleaks in cases with short landing zones.

Current status of carotid bifurcation angioplasty and stenting based on a consensus of opinion leaders

OBJECTIVE

Carotid bifurcation angioplasty and stenting (CBAS) has generated controversy and widely divergent opinions about its current therapeutic role. To resolve differences and establish a unified view of CBAS' present role, a consensus conference of 17 experts, world opinion leaders from five countries, was held on November 21, 1999.

METHODS

These 17 participants had previously answered 18 key questions on current CBAS issues. At the conference these 18 questions and participants' answers were discussed and in some cases modified to determine points of agreement (consensus), near consensus, (prevailing opinion), or divided opinion (disagreement).

RESULTS

Conference discussion added two modified questions, placing a total of 20 key questions before the participants, representing four specialties (interventional radiology, seven; vascular surgery, six; interventional cardiology, three; neurosurgery, one). It is interesting that consensus was reached on the answers to 11 (55%) of 20 of the questions, and near consensus was reached on answers to 6 (30%) of 20 of the questions. Only with the answers to three (15%) of the questions was there persisting controversy. Moreover, both these differences and areas of agreement crossed specialty lines. Consensus Conclusions: CBAS should not currently undergo widespread practice, which should await results of randomized trials. CBAS is currently appropriate treatment for patients at high risk in experienced centers. CBAS is not generally appropriate for patients at low risk. Neurorescue skills should be available if CBAS is performed. When cerebral protection devices are available, they should be used for CBAS. Adequate stents and technology for performing CBAS currently exist. There were divergent opinions regarding the proportions of patients presently acceptable for CBAS treatment (<5% to 100%, mean 44%) and best treated by CBAS (<3% to 100%, mean 34%). These and other consensus conclusions will help physicians in all specialties deal with CBAS in a rational way rather than by being guided by unsubstantiated claims.

Combined minimaly invasive surgery for coronary bypass and abdominal aortic occlusion

Association of extracorporal assisted coronary bypass with peripheral vascular surgery is already commonplace in the therapeutic arsenal. This case report presents a combined cardiac and vascular surgery in a high risk patient, with unstable angina following myocardial infarction and critical ischemia of a single lower limb. Synchronous minimally invasive direct coronary bypass graft and extra-anatomic aorto-profundal bypass in one single sitting were performed. The procedure was successful at 6 months follow up. We believe that this type of synchronous procedure, minimising surgical aggression, could be effective in selected high risk patients.

Global experience in cervical carotid artery stent placement

The purpose of this article is to review and update the current status of carotid artery stent placement in the world. Surveys to major interventional centers in Europe, North and South America, and Asia were initially completed in June 1997. Subsequent information from these 24 centers in addition to 12 new centers has been obtained to update the information. The survey asked the various questions regarding the patients enrolled, procedure techniques, and results of carotid stenting, including complications and restenosis. The total number of endovascular carotid stent procedures that have been performed worldwide to date included 5,210 procedures involving 4,757 patients. There was a technical success of 98.4% with 5,129 carotid arteries treated. Complications that occurred during the carotid stent placement or within a 30-day period following placement were recorded. Overall, there were 134 transient ischemic attacks (TIAs) for a rate of 2.82%. Based on the total patient population, there were 129 minor strokes with a rate of occurrence of 2.72%. The total number of major strokes was 71 for a rate of 1.49%. There were 41 deaths within a 30-day postprocedure period resulting in a mortality rate of 0.86%. The combined minor and major strokes and procedure-related death rate was 5.07%. Restenosis rates of carotid stenting have been 1.99% and 3.46% at 6 and 12 months, respectively. The rate of neurologic events after stent placement has been 1.42% at 6-12-month follow-up. Endovascular stent treatment of carotid artery atherosclerotic disease is growing as an alternative for vascular surgery, especially for patients that are high risk for standard carotid endarterectomy. The periprocedure risks for major and minor strokes and death are generally acceptable at this early stage of development and have not changed significantly since the first survey results. Cathet. Cardiovasc. Intervent. 50:160-167, 2000.

First-generation aortic endografts: analysis of explanted Stentor devices from the EUROSTAR Registry

PURPOSE

To examine the structure and healing characteristics of chronically implanted Stentor endografts that were explanted due to migration, endoleak, thrombosis, or aneurysm expansion.

METHODS

The devices were harvested following reoperation (n = 5) or autopsy (n = 1) with implantation times ranging from 13 to 53 months. Structural modifications to the metal components were examined using radiography, endoscopy, and magnetic resonance imaging (MRI). Specimens taken from components of the modular stent-grafts were examined histologically and with scanning electron microscopy (SEM) to assess healing behavior. Physical and chemical stability of the nitinol wires and woven polyester graft material was evaluated using SEM and electron spectroscopy for chemical analysis.

RESULTS

Although the endografts were retrieved for a variety of reasons, they exhibited similar healing and structural modifications. The woven polyester sleeve showed evidence of yarn shifting and distortion, yarn damage, and filament breakage leading to the formation of openings in the fabric. The luminal surface endografts showed incomplete healing characterized by a poorly organized, nonadherent thrombotic matrix of variable thickness. Radiographic and endoscopic observations indicated that structural failure of the grafts, particularly in the main aortic component, was related to severe compaction and dislocation of the metallic frame due to suture breaks. Corrosion marks were observed on some nitinol wires in all devices. Chemical analysis and ion bombardment of the nitinol wires revealed that the surface concentrations of titanium and nickel were not homogenous. The first layer was composed of carbon or organic elements, followed by a stratum of highly oxidized titanium with a low nickel concentration; the titanium-nickel alloy lay beneath these layers.

CONCLUSIONS

Although the materials selected for construction of endovascular grafts appears judicious, the assembly of these biomaterials into various interrelated structures within the device requires further improvement.

First-generation aortic endografts: analysis of explanted Stentor devices from the EUROSTAR Registry

PURPOSE

To examine the structure and healing characteristics of chronically implanted Stentor endografts that were explanted due to migration, endoleak, thrombosis, or aneurysm expansion.

METHODS

The devices were harvested following reoperation (n = 5) or autopsy (n = 1) with implantation times ranging from 13 to 53 months. Structural modifications to the metal components were examined using radiography, endoscopy, and magnetic resonance imaging (MRI). Specimens taken from components of the modular stent-grafts were examined histologically and with scanning electron microscopy (SEM) to assess healing behavior. Physical and chemical stability of the nitinol wires and woven polyester graft material was evaluated using SEM and electron spectroscopy for chemical analysis.

RESULTS

Although the endografts were retrieved for a variety of reasons, they exhibited similar healing and structural modifications. The woven polyester sleeve showed evidence of yarn shifting and distortion, yarn damage, and filament breakage leading to the formation of openings in the fabric. The luminal surface endografts showed incomplete healing characterized by a poorly organized, nonadherent thrombotic matrix of variable thickness. Radiographic and endoscopic observations indicated that structural failure of the grafts, particularly in the main aortic component, was related to severe compaction and dislocation of the metallic frame due to suture breaks. Corrosion marks were observed on some nitinol wires in all devices. Chemical analysis and ion bombardment of the nitinol wires revealed that the surface concentrations of titanium and nickel were not homogenous. The first layer was composed of carbon or organic elements, followed by a stratum of highly oxidized titanium with a low nickel concentration; the titanium-nickel alloy lay beneath these layers.

CONCLUSIONS

Although the materials selected for construction of endovascular grafts appears judicious, the assembly of these biomaterials into various interrelated structures within the device requires further improvement.

Percutaneous stenting of the internal carotid artery: the European CAST I Study. Carotid Artery Stent Trial

PURPOSE

To report the results of a multicenter safety trial of percutaneous carotid stenting performed by vascular surgeons.

METHODS

Symptomatic or asymptomatic patients > or = 65 years of age with internal carotid artery (ICA) stenoses > or = 70% and < or = 2-cm long were eligible for enrollment. The procedures were performed in an operating room with the choice of anesthesia and the percutaneous access site at the discretion of the surgeon. Only Palmaz stents were used.

RESULTS

From January 1, 1996 to December 31, 1997, 99 patients (74 men, mean age 70 years, range 51 to 94) were enrolled in the study. More than half (57 of 99 patients) were asymptomatic. The direct cervical approach was used predominantly (97%). Three (3%) cases were converted to surgery for inability to access the artery or deploy the stent (technical success 97%). No perioperative death or myocardial infarction was reported. Six (6%) procedural complications included 1 reversible arterial spasm, 2 dissections, 1 cervical hematoma, and 2 residual stenoses. One neurological event reversed within 7 days (1% minor stroke rate) and 4 (4%) transient ischemic attacks resolved within 24 hours. One (1%) asymptomatic early occlusion occurred 2 days postoperatively. No neurological event was observed in the 1- to 24-month follow-up (mean 13 months). Two (2%) patients died of nonprocedurally related causes. No stent compression was seen, but 1 asymptomatic occlusion and 3 asymptomatic, non-flow-limiting restenoses (2 < 40%, 1 at 60%) were found within 1 year (3% restenosis rate on an intention-to-treat basis). Patency was 98% at 1 year.

CONCLUSIONS

The results of this trial support the contention that carotid stenting of short ICA lesions can be performed with a low neurological complication rate.

Current global status of carotid artery stent placement

Our purpose was to review the current status of carotid artery stent placement throughout the world. Surveys were sent to major interventional centers in Europe, North and South America, and Asia. Information from peer-reviewed journals was also included and supplemented the survey. The survey asked various questions regarding the patients enrolled, procedure techniques, and results of carotid stenting, including complications and restenosis. Of the centers which were sent surveys, 24 responded. The total number of endovascular carotid stent procedures that have been performed worldwide to date included 2,048 cases, with a technical success of 98.6%. Complications that occurred during carotid stent placement or within a 30-day period following placement were recorded. Overall, there were 63 minor strokes, with a rate of occurrence of 3.08%. The total number of major strokes was 27, for a rate of 1.32%. There were 28 deaths within a 30-day postprocedure period, resulting in a mortality rate of 1.37%. Restenosis rates of carotid stenting have been 4.80% at 6 mo. Endovascular stent treatment of carotid artery atherosclerotic disease is growing as an alternative to vascular surgery, especially for patients that are at high risk for standard carotid endarterectomy. The periprocedural risks for major and minor strokes and death are generally acceptable at this early stage of development.

Hemodynamics of endovascular prostheses

A surgical study (Bergeron et al., 1991, International Angiology 10(3), 182-186) picked out that re-endothelialization of implanted expandable stents, frequently used to reduce the recurrent stenosis rate after balloon angioplasty, was correct and more rapid in femoro-popliteal arteries (quasi-straight vessels) than in iliac arteries (bifurcated vessels). Since it is now well known that local hemodynamics are considered to be an important atherogenic factor, we decided to compare and optimize the shape of the existing equipment, in order to further give some informations to surgeons about the optimal stenting at the site of bifurcation. Therefore, we studied in vitro (1) the influence of the protruding part of a stent on the flow patterns in the branches of an aorto-iliac bifurcation model, and (2) the possibility of reducing or preventing this impact. Qualitative information was obtained from visualizations in the horizontal median plane of the bifurcation model, while Doppler ultrasonic velocimetry provided quantitative data, at different points of the cardiac cycle. Results showed that a standard stent implanted in a daughter branch of the bifurcation may have a considerable influence on flow behaviour when it is sticking out of the daughter branch. A new design of stent, with a bevelled shape, showed a significant reduction of flow disturbance.

Endoluminal repair of large abdominal aortic aneurysms using PTFE: a feasibility study

PURPOSE

To investigate the feasibility of using predilated thin-wall polytetrafluoroethylene (PTFE) secured by extra-large Palmaz stents for endoluminal repair of abdominal aortic aneurysms (AAA).

METHODS

Thirty-two patients (26 males; aged 69 to 83 years) from three centers (two in Europe, one in Australia) were selected for endoluminal stent-grafting using predilated B-mm PTFE graft material fitted with extra-large Palmaz stents at the terminal ends. Aortoaortic tube grafts were implanted in 12 patients, while the remainder received aortomonoiliac endografts and femorofemoral bypass. Follow-up at 5 days and then biannually was by contrast-enhanced computed tomography (CT) or duplex scanning.

RESULTS

There were 13 conversions to open surgery; these patients died within 30 days. Nineteen patients were discharged with functioning endografts within 5 days of treatment. Of these, two have had their grafts removed owing to infection in one and distal stent migration in the other. Two endoleaks have been detected in follow-up; one has been sealed by covered stenting. One twisted graft was repaired by Wallstent implantation. Seventeen patients remain well, one with persistent distal endoleak, but none shows an increase in AAA diameter on imaging over the 6- to 26-month (median 13) follow-up.

CONCLUSIONS

These results represent the learning curves of three separate centers. Technical failure and complications were more common early in the study. Advantages of the technique include relative low cost and the ability to tailor the stent-graft to the individual aneurysm.

Women physicians in Quebec

This article presents the results of a qualitative study on women physicians in Quebec which aimed to go beyond a mere statistical description of the tendencies observed in their practices. It proposes an interpretation of their discourses on their practice and its context bringing to light the interdependence of individual strategies and structural constraints. We met 30 women physicians and eight men physicians asking them to talk freely about their personal and professional experience. The data reveal how the individual characteristics and interests of women physicians prevail in their decisions at key moments in their lives which have repercussions on the shaping of their practice. These moments include admission into the faculty of medicine, training, professional orientation and the choice of a specialized field, organization of professional practice and personal life. The medical practice of women is constructed through these choices and the gender variable plays a more or less significant role at each stage of this construction. Their distinctive choices reflect how gender relations are reproduced in the private sphere and the interactions between their private and professional lives. According to our participants, a difference lies in the place occupied by their profession in women and men physicians' lives. The private life of women physicians appears to be closely linked to their decisions regarding the organization of their professional life and as a result to the health services they provide, suggesting they have their own way of "being a physician". The individual nature of the strategies they adopt can have, at a collective level, consequences on the planning and the distribution of medical resources in the publicly managed health care system in Quebec while raising the global issue of gendered division of labor.

Evaluation of endovascular abdominal aortic aneurysm repair: anatomical classification, procedural success, clinical assessment, and data collection

PURPOSE

To detail a methodology for evaluation of endovascular abdominal aortic aneurysm (AAA) repair that has been achieved through consensus of an international multidisciplinary team of investigators.

METHODS

This schema features an anatomical classification for AAAs, a definition of procedural success, and a procedure for clinical assessment, as well as the necessary data collection forms. Patient data include demographics, procedural and clinical success, complications, and follow-up. Procedural details can be related to anatomic situations, comorbid processes, devices, and effective aneurysmal exclusion.

RESULTS

These data would allow assessment of the procedures, physician learning curves, procedural indications, techniques, methodologies, the relationship of indications to success and complications, devices and subsequent graft patency, and aneurysmal exclusion.

CONCLUSIONS

The use of this standardized data collection system could enable physicians and industry to better understand endovascular AAA repair and ultimately improve patient care.