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1.
Int J Low Extrem Wounds ; : 15347346241238458, 2024 Mar 20.
Article in English | MEDLINE | ID: mdl-38504634

ABSTRACT

OBJECTIVE: This study evaluated the toe and flow model (TFM), a limb preservation program led by podiatric surgeons in Alberta, Canada, for its impact on hospitalization rates and length of stay (LOS) in patients with diabetic foot complication (DFC). Diabetes, a leading cause of non-traumatic lower extremity amputations (LEAs) in Canada, often results in diabetic foot ulcers (DFUs), a major cause of infection, amputation, and hospitalization. TFM has reportedly reduced amputation rates by 39% to 56%. METHODS: The study analyzed Alberta's health database from 2007 to 2017, focusing on diabetes patients aged 20 and above. It included patients with various DFCs and compared outcomes in regions using TFM and standard of care (SOC). The study also examined data from two major cities, one with TFM and the other without, including rural referrals to Calgary and Edmonton. The data were normalized for the diabetic population and analyzed using a standard Student's t-test. RESULTS: TFM regions showed significantly lower hospitalization rates (p = 1.22E-12) than SOC regions. Over 11 years, TFM maintained lower average and median LOS by 0.13 and 0.26 days, respectively. TFM access reduced hospitalization risk by up to 30%, and patients in TFM regions had a 21% shorter LOS compared to SOC regions. CONCLUSION: Despite similar demographics and healthcare systems, the TFM region benefited from a dedicated multidisciplinary program and comprehensive limb preservation services. The study shows that TFM effectively reduces hospitalizations and LOS for DFCs, with significantly better outcomes in the TFM region than in SOC regions.

2.
J Vasc Surg Cases Innov Tech ; 10(2): 101410, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38379612

ABSTRACT

A case of a young patient with incidental bilateral internal iliac artery aneurysms and common iliac artery aneurysms is described. A staged hybrid surgical approach was performed to preserve pelvic perfusion, with bilateral stent grafts deployed into an ipsilateral anterior division branch and contralateral posterior division branch of the internal iliac arteries. One week later, an open infrarenal aorto-bi-iliac graft was performed with distal anastomoses to the previously deployed stent grafts. The findings from the present case add to the growing number of reported cases of hybrid repair of bilateral internal iliac and common iliac artery aneurysms with preservation of pelvic perfusion.

3.
NEJM Evid ; 3(3): EVIDmr2300300, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38411448

ABSTRACT

A 52-Year-Old Woman with Weakness and ConfusionA 52-year-old woman presented for evaluation of abdominal pain, weakness, and confusion. How do you approach the evaluation, and what is the diagnosis?


Subject(s)
Abdominal Pain , Confusion , Female , Humans , Middle Aged , Confusion/diagnosis , Abdominal Pain/diagnosis
4.
Can J Cardiol ; 39(11): 1484-1498, 2023 11.
Article in English | MEDLINE | ID: mdl-37949520

ABSTRACT

Disease of the aortic arch, descending thoracic, or thoracoabdominal aorta necessitates dedicated expertise across medical, endovascular, and surgical specialties. Cardiologists, cardiac surgeons, vascular surgeons, interventional radiologists, and others have expertise and skills that aid in the management of patients with complex aortic disease. No specialty is uniformly expert in all aspects of required care. Because of this dispersion of expertise across specialties, an aortic team model approach to decision-making and treatment is advocated. A nonhierarchical partnership across specialties within an interdisciplinary aortic clinic ensures that all treatment options are considered and promotes shared decision-making between the patient and all aortic experts. Furthermore, regionalization of care for aortic disease of increased complexity assures that the breadth of treatment options is available and that favourable volume-outcome ratios for high-risk procedures are maintained. An awareness of best practice care pathways for patient referrals for preventative management, acute care scenarios, chronic care scenarios, and pregnancy might facilitate a more organized management schema for aortic disease across Canada and improve lifelong surveillance initiatives.


Subject(s)
Aortic Diseases , Specialties, Surgical , Surgeons , Humans , Radiology, Interventional , Canada , Aortic Diseases/diagnosis , Aortic Diseases/surgery , Aorta , Vascular Surgical Procedures
5.
J Vasc Surg Cases Innov Tech ; 9(4): 101274, 2023 Dec.
Article in English | MEDLINE | ID: mdl-37822947

ABSTRACT

Objective: The objective is to describe the initial Canadian experience using novel aortic arch branched endograft technologies. Methods: We performed a retrospective consecutive case series of all patients undergoing aortic arch branched repair with newly available endograft technology since 2020 at our site. We describe the patient characteristics, treatment characteristics, and postoperative outcomes. Results: Eleven patients received arch branched endografts, indicated for penetrating aortic ulcer in seven patients (64%), arch degeneration after prior aortic dissection repair in three (27%), and acute aortobronchial fistula in one patient (9%). Their average age was 72 ± 7 years. Complete arch repair from zone 0 to 4 was performed in six cases (55%); the remaining repairs landed proximally in zones 1 or 2. Seven repairs used a single retrograde facing inner branch (thoracic branch endoprosthesis; W.L. Gore & Associates), three used double antegrade inner branch (Bolton Relay; Terumo Interventional Systems), and one emergent case used double in situ fenestrations. Seven repairs (64%) used an adjunctive extra-anatomic bypass to complete great vessel perfusion, two of which were created during a prior aortic repair. Inferior vena cava balloon inflow occlusion during deployment was used in all cases. No mortalities, transient or permanent spinal cord paralysis, myocardial infarction, dialysis dependence, venous thromboembolism, or bleeding requiring reintervention occurred. No patient undergoing elective arch branch repair experienced a stroke. The one patient undergoing emergent repair did suffer a stroke. The median length of stay was 5 days (interquartile range, 2-8 days). Two endoleaks developed: a type Ia endoleak successfully treated with a Palmaz stent (Cordis) during the index admission, and a type II endoleak with ongoing sac regression on postoperative follow-up. Postoperatively, one patient suffered a suspected aortic graft infection that was treated with lifelong antibiotics. During a mean radiographic follow-up of 7.2 months, no cases of branch vessel instability (ie, no migration, reintervention, arterial rupture, intraluminal thrombus, occlusion, stenosis, or kinking of the branch grafts) developed. Three patients experienced sac regression of >5 mm, and no patient experienced continued postoperative dilation. Conclusions: To the best of our knowledge, this is the largest reported Canadian volume of aortic arch repair using novel branched or fenestrated technology. The series demonstrates that a multidisciplinary program and properly selected patients can yield excellent results using endovascular repair for complex aortic arch pathology.

6.
J Vasc Surg Cases Innov Tech ; 9(2): 101141, 2023 Jun.
Article in English | MEDLINE | ID: mdl-37152911

ABSTRACT

In the present report, we describe the case of a patient with an infrarenal abdominal aortic aneurysm that had been incidentally noted on an imaging study. Treatment decisions for this case were complicated by the presence of a hostile infrarenal aortic neck and significant bilateral iliac artery circumferential calcification, precluding iliac artery clamping and standard distal anastomotic techniques. We performed a hybrid surgical procedure, deploying bilateral iliac stent grafts into the distal aneurysmal aorta and sewing our aortic graft to the proximal extent of these stents. The findings from the present case add to the previously reported techniques of hybrid surgical management of abdominal aortic aneurysms with iliac disease and expand the technique to a larger application.

7.
Can J Cardiol ; 39(1): 49-56, 2023 01.
Article in English | MEDLINE | ID: mdl-36395997

ABSTRACT

BACKGROUND: Total endovascular aortic arch repair (TEAAR) represents an emerging alternative for the treatment of aortic arch disease in patients at prohibitive risk for open surgery. A systematic review of TEAAR was performed to delineate early outcomes with this new technology. METHODS: All studies (excluding single-patient case reports) of CE-certified "custom made" or "off-the-shelf" zone 0 stent graft deployments were included. The primary search of Medline, Embase, CINAHL, and the Cochrane CENTRAL registry was supplemented with searches of Web of Science, ClinicalTrials.gov, and conference abstracts (within last 3 years), and a hand search of citations within relevant articles. Articles underwent 2-stage screening by 2 independent reviewers before inclusion. RESULTS: Fifteen relevant investigations were identified. Indications for TEAAR were chronic arch dissection with degenerative aneurysmal disease (54%, 148/273), pure arch aneurysm (41%, 112/273), penetrating atherosclerotic ulcer (2%, 5/273), and type IA endoleak from a zone 2 thoracic endograft (1%, 3/273). Double-branch (70%, 192/273), triple-branch (19%, 53/273), and single-branch (into innominate artery; 10%, 28/273) devices were used. Adjunct left carotid-subclavian bypass occurred in 90% of double- and single-branch procedures. Procedural success with TEAAR was 93% (95% CI 85.8%-96.3%). The proportion of all-cause mortality was 16% (95% CI 8%-26%), stroke 14% (8%-24%), peripheral vascular events 7% (1%-33%), and myocardial infarction 4% (2%-7%). Endoleaks were identified in 13% (7%-25%) of the study population. CONCLUSIONS: TEAAR represents an emerging option for the management of aortic arch disease wth high procedural success rates and acceptable early outcomes in a high-risk patient population.


Subject(s)
Aortic Aneurysm, Thoracic , Aortic Dissection , Blood Vessel Prosthesis Implantation , Endovascular Procedures , Humans , Aorta, Thoracic/diagnostic imaging , Aorta, Thoracic/surgery , Blood Vessel Prosthesis , Aortic Aneurysm, Thoracic/diagnosis , Aortic Aneurysm, Thoracic/surgery , Aortic Aneurysm, Thoracic/etiology , Blood Vessel Prosthesis Implantation/methods , Treatment Outcome , Stents , Retrospective Studies
8.
Aorta (Stamford) ; 11(6): 165-173, 2023 Dec.
Article in English | MEDLINE | ID: mdl-38698622

ABSTRACT

BACKGROUND: This study aimed to assess feasibility, logistical challenges, and clinical outcomes associated with the implementation of an Aortic Team model for the management of distal arch, descending thoracic and thoracoabdominal aortic disease. METHODS: An Aortic Team care pathway was implemented in November 2019. Working as a unit, two cardiac surgeons, two vascular surgeons, an interventional radiologist, a cardiologist, and an anesthesiologist collectively determined care decisions via multispecialty presence at an Aortic Clinic. Cardiac and vascular surgeons operated in tandem for open procedures. Interventional radiology participated alongside cardiac and vascular for endovascular procedures. Cardiology aided in medical therapies for heritable and degenerative disease, and had a lead role for genetics and high-risk pregnancy referrals. The model spanned three hospitals. Clinical outcomes at 3 years were assessed. RESULTS: There were 35 descending thoracic and thoracoabdominal surgeries and 77 thoracic endovascular aortic repairs. Endoarch devices were used in 7 cases (Gore Thoracic Branch Endoprosthesis, 4, Terumo RelayBranch, 3) and an endothoracoabdominal device in 4 cases (Cook Zenith t-branch). The Aortic Clinic acquired 456 patients, with yearly increases (54 patients [year 1], 181 patients [year 2], 221 patients [year 3]). For surgery, mortality was 8.6% (3/35), permanent paralysis 5.7% (2/35), stroke 8.6% (3/35), permanent dialysis 0%, and reinterventions 8.6% (3/35). For endovascular cases, mortality was 3.9% (3/77), permanent paralysis 3.9% (3/77), stroke 5.2% (4/77), permanent dialysis 1.3% (1/77), and reinterventions 16.9% (13/77). CONCLUSION: An Aortic Team model is feasible and ensures all treatment options are considered. Conventional open thoracoabdominal procedures showed acceptable outcomes. Endoarch technology shows early promise.

9.
CJC Open ; 3(10): 1307-1309, 2021 Oct.
Article in English | MEDLINE | ID: mdl-34888511

ABSTRACT

Endovascular therapies have had a considerable impact on contemporary management of thoracic aortic disease. Still, with the anatomic challenges of the aortic arch, endovascular experience with devices that traverse the arch and deploy in the Zone 0 position remains limited. We report the first Canadian experience with the RelayBranch Thoracic Stent Graft (Terumo Aortic, Sunrise, FL) with Zone 0 deployment for total endovascular aortic arch repair in a patient at very high risk for redo open surgery. We demonstrate safe deployment of the device and successful treatment of a type 1A endoleak. Features of the RelayBranch design that mitigate challenges of arch deployment are also discussed.


Les traitements endovasculaires ont eu un impact considérable sur la gestion contemporaine des pathologies de l'aorte thoracique. Pourtant, en raison des contraintes anatomiques de la crosse aortique, l'expérience endovasculaire avec des dispositifs qui traversent la crosse et se déploient dans la zone 0 reste limitée. Nous rapportons la première expérience canadienne de l'endoprothèse thoracique RelayBranch avec déploiement (Terumo Aortic, Sunrise, FL) en zone 0 pour une réparation endovasculaire totale de la crosse aortique chez un patient présentant un risque très élevé de reprise de chirurgie ouverte. Nous décrivons le déploiement en toute sécurité du dispositif et le traitement réussi d'une endofuite de type 1A. Enfin, nous examinons les caractéristiques du système RelayBranch qui limitent les difficultés liées au déploiement du dispositif dans la crosse aortique.

10.
CJC Open ; 3(6): 787-800, 2021 Jun.
Article in English | MEDLINE | ID: mdl-34169258

ABSTRACT

BACKGROUND: Several specialties treat thoracic aortic disease, resulting in multiple patient care pathways. This study aimed to characterize these varied care models to guide health policy. METHODS: A 57-question e-survey was sent to staff cardiac surgeons, cardiologists, interventional radiologists, and vascular surgeons at 7 Canadian medical societies. RESULTS: For 914 physicians, the response rate was 76% (86 of 113) for cardiac surgeons, 40% (58 of 146) for vascular surgeons, 24% (34 of 140) for radiologists, and 14% (70 of 515) for cardiologists. Several services admitted type B dissections (vascular 37%, cardiology 31%, cardiac 18%, other 7%), and care was heterogeneous. Ownership of disease management was overestimated relative to the perspective of the other specialties. Type A dissection admissions and treatment were more uniform, but emergent call coverage varied. A 24/7 aortic specialist on-call schedule was present only 4% of the time. "Aortic" case rounds promoted attendance by a broader aortic specialty contingency relative to rounds that were specialty specific. Although 89% of respondents felt an aortic team was best for patient care, only 54% worked at an institution with an aortic team present, and only 28% utilized an aortic clinic. Questions designed to define an aortic team derived 63 different combinations. CONCLUSIONS: Thoracic aortic disease follows a network of undefined and variable care pathways, despite its high-risk population in need of complex treatment considerations. Multidisciplinary aortic teams and clinics exist in low volume, and the "aortic team" remains an obscure construct. A multispecialty initiative to define the aortic team and outline standardized navigation pathways within the health systems hospitals is advocated.


CONTEXTE: La prise en charge de la maladie de l'aorte thoracique peut faire appel à plusieurs spécialités, ce qui a pour effet de multiplier les trajectoires de soins des patients. Cette étude visait à caractériser ces différents modèles de soins afin d'éclairer l'élaboration des politiques de santé. MÉTHODOLOGIE: Un sondage électronique de 57 questions a été envoyé aux chirurgiens cardiaques, aux cardiologues, aux radiologistes interventionnels et aux chirurgiens vasculaires membres de 7 associations médicales canadiennes. RÉSULTATS: Sur un total de 914 médecins, le taux de réponse a été de 76 % (86 sur 113) chez les chirurgiens cardiaques, de 40 % (58 sur 146) chez les chirurgiens vasculaires, de 24 % (34 sur 140) chez les radiologistes et de 14 % (70 sur 515) chez les cardiologues. Plusieurs services avaient admis des cas de dissection aortique de type B (chirurgie vasculaire 37 %, cardiologie 31 %, chirurgie cardiaque 18 %, autre 7 %) et les soins étaient hétérogènes. Les spécialistes surestimaient leur responsabilité de la prise en charge des cas par rapport à celle des autres spécialistes. Les admissions de cas de dissection de type A et leur traitement étaient plus uniformes, mais la présence de spécialistes de garde pouvant traiter les cas urgents était variable. La présence continue d'un spécialiste de l'aorte de garde n'était observée que pendant 4 % du temps. Les séances de discussion de cas « aortiques ¼ favorisaient la participation par une gamme plus large de spécialistes de l'aorte que les discussions axées sur une spécialité donnée. Si 89 % des répondants estimaient qu'une équipe « aortique ¼ était la meilleure option pour les soins aux patients, ils n'étaient que 54 % à travailler dans un établissement disposant d'une telle équipe et 28 % à utiliser les services d'une clinique de l'aorte. En réponse aux questions portant sur les éléments constitutifs d'une équipe aortique, 63 combinaisons différentes de spécialités ont été proposées. CONCLUSIONS: La prise en charge de la maladie de l'aorte thoracique emprunte un dédale de trajectoires de soins non définies et variables, alors que sa population à haut risque a besoin de traitements complexes. Les équipes multidisciplinaires et les cliniques spécialisées dans le traitement de l'aorte sont rares, et la notion d' « équipe aortique ¼ demeure un concept obscur. Nous préconisons une initiative réunissant des spécialistes de différents domaines pour définir les éléments constitutifs d'une équipe aortique et établir des trajectoires de navigation normalisées au sein des hôpitaux du système de santé.

11.
J Vasc Surg ; 74(4): 1135-1142.e1, 2021 10.
Article in English | MEDLINE | ID: mdl-33864828

ABSTRACT

OBJECTIVE: In the present study, we defined the outcomes and effects of pregnancy in a cohort of women of childbearing age with acute aortic dissection (AAD). METHODS: We reviewed our database of AAD to identify all eligible female patients. Women aged <45 years were included. Data on pregnancy timing with respect to the occurrence of dissection, the demographic data, dissection extent, dissection treatment, dissection-related outcomes, overall maternal and fetal mortality, and genetic testing results were analyzed. RESULTS: A total of 62 women aged <45 years had presented to us with AAD from 1999 to 2017. Of the 62 women, 37 (60%) had had a history of pregnancy at AAD. Of these 37 patients, 10 (27%) had had a peripartum aortic dissection, defined as dissection during pregnancy or within 12 months postpartum. Of the 10 AADs, 5 were type A and 5 were type B. Three patients had presented with AAD during pregnancy (one in the second and two in the third trimester). Five patients (50%) had developed AAD in the immediate postpartum period (within 3 months) and two (20%) in the late postpartum period. For the immediate postpartum AADs (<3 months), four of the five patients delivered via cesarean section. Of these 10 peripartum AADs, 3 (30%) had occurred in patients with known Marfan syndrome. In-hospital mortality for those with peripartum AAD was 10% (1 of 10). Fetal mortality was 20% (2 of 10). CONCLUSIONS: The frequency of aortic dissection in women of childbearing age at our institution was low. However, pregnancy might increase the risk of those young women genetically predisposed to dissection events. From these data, this risk appears to be greatest in the immediate postpartum period, even for those who undergo cesarean section. Close clinical and radiographic surveillance is required for all women with suspected aortopathy, especially in the third trimester and early postpartum period.


Subject(s)
Aortic Aneurysm/epidemiology , Aortic Dissection/epidemiology , Hospitalization , Maternal Age , Pregnancy Complications, Cardiovascular/epidemiology , Reproductive Health , Adult , Aortic Dissection/diagnostic imaging , Aortic Dissection/mortality , Aortic Dissection/therapy , Aortic Aneurysm/diagnostic imaging , Aortic Aneurysm/mortality , Aortic Aneurysm/therapy , Databases, Factual , Female , Hospital Mortality , Humans , Maternal Mortality , Middle Aged , Pregnancy , Pregnancy Complications, Cardiovascular/diagnostic imaging , Pregnancy Complications, Cardiovascular/mortality , Pregnancy Complications, Cardiovascular/therapy , Prognosis , Retrospective Studies , Risk Assessment , Risk Factors , Texas/epidemiology , Time Factors
12.
Ann Thorac Surg ; 109(3): e187-e189, 2020 03.
Article in English | MEDLINE | ID: mdl-31454526

ABSTRACT

Since its approval by the United States Food and Drug Administration in 2011, transcatheter aortic valve replacement has revolutionized the treatment of aortic valvular disease with a rapid increase in use. Potentially fatal aortic complications are rare, occurring in 0.2% to 1.1% of cases-all reported in the early perioperative period. We present a case of a late ascending aortic pseudoaneurysm with rupture secondary to erosion by an embolized transcatheter aortic valve occurring 6 years after implantation. The patient was successfully treated with a commercially available, off-the-shelf aortic endograft.


Subject(s)
Aneurysm, False/etiology , Aneurysm, False/surgery , Aorta/surgery , Aortic Aneurysm/etiology , Aortic Aneurysm/surgery , Aortic Rupture/etiology , Aortic Rupture/surgery , Aortic Valve , Embolism/complications , Endovascular Procedures , Heart Valve Diseases/complications , Postoperative Complications/etiology , Postoperative Complications/surgery , Transcatheter Aortic Valve Replacement , Aged, 80 and over , Female , Humans
13.
Semin Thorac Cardiovasc Surg ; 31(4): 697-702, 2019.
Article in English | MEDLINE | ID: mdl-30980932

ABSTRACT

The management of the aortic arch aneurysm is becoming increasingly complex and multidisciplinary. It has evolved since the first successful repair by DeBakey et al in 1957. After these initial repairs, the improvement in open surgical techniques, cardiopulmonary bypass, anesthesia, and perioperative care were the primary drivers of the decrease in morbidity and mortality associated with repair. The development of endovascular technology has spurred another revolution in the management of aortic arch aneurysms. In this review, we present a current appraisal and description of open surgical, hybrid, and endovascular techniques based on the literature. These techniques are varied and have different advantages and disadvantages, depending on patient anatomy and perioperative surgical risk. We provide an overview of the attributes of each technique and how they may be applied to individual cases. While each technique could not be discussed in detail in this report, it is clear that institutions must be able to proficiently offer the full spectrum of open, hybrid, and endovascular surgical techniques to treat this diverse condition. For low and intermediate risk patients, open surgery remains the gold standard. However, just as improvements in technique, monitoring and perioperative care led to progress in open repair, similar advancements in endograft technology, anatomical customization, and embolic protection will expand the use of endovascular repair. As the management of the condition becomes increasingly nuanced and multidisciplinary, centers must be equipped to offer a variety of techniques with high fidelity and adaptability to each unique patient.


Subject(s)
Aorta, Thoracic/surgery , Aortic Aneurysm, Thoracic/surgery , Blood Vessel Prosthesis Implantation , Endovascular Procedures , Aorta, Thoracic/diagnostic imaging , Aorta, Thoracic/physiopathology , Aortic Aneurysm, Thoracic/diagnostic imaging , Aortic Aneurysm, Thoracic/mortality , Aortic Aneurysm, Thoracic/physiopathology , Blood Vessel Prosthesis , Blood Vessel Prosthesis Implantation/adverse effects , Blood Vessel Prosthesis Implantation/instrumentation , Blood Vessel Prosthesis Implantation/mortality , Endovascular Procedures/adverse effects , Endovascular Procedures/instrumentation , Endovascular Procedures/mortality , Humans , Postoperative Complications/mortality , Prosthesis Design , Risk Assessment , Risk Factors , Stents , Treatment Outcome
14.
Can J Surg ; 55(4): S184-90, 2012 Aug.
Article in English | MEDLINE | ID: mdl-22854146

ABSTRACT

BACKGROUND: Surgery training programs in Canada and the United States have recognized the need to modify current models of training and education. The shifting demographic of surgery trainees, lifestyle issues and an increased trend toward subspecialization are the major influences. To guide these important educational initiatives, a contemporary profile of Canadian general surgery residents and their impressions of training in Canada is required. METHODS: We developed and distributed a questionnaire to residents in each Canadian general surgery training program, and residents responded during dedicated teaching time. RESULTS: In all, 186 surveys were returned for analysis (62% response rate). The average age of Canadian general surgery residents is 30 years, 38% are women, 41% are married, 18% have dependants younger than 18 years and 41% plan to add to or start a family during residency. Most (87%) residents plan to pursue postgraduate education. On completion of training, 74% of residents plan to stay in Canada and 49% want to practice in an academic setting. Almost half (42%) of residents identify a poor balance between work and personal life during residency. Forty-seven percent of respondents have appropriate access to mentorship, whereas 37% describe suitable access to career guidance and 40% identify the availability of appropriate social supports. Just over half (54%) believe the stress level during residency is manageable. CONCLUSION: This survey provides a profile of contemporary Canadian general surgery residents. Important challenges within the residency system are identified. Program directors and chairs of surgery are encouraged to recognize these challenges and intervene where appropriate.


Subject(s)
Career Choice , General Surgery/education , Internship and Residency/organization & administration , Leadership , Adult , Alberta , Clinical Competence , Cross-Sectional Studies , Education, Medical, Graduate/organization & administration , Female , Humans , Job Satisfaction , Male , Personal Satisfaction , Problem-Based Learning , Program Evaluation , Risk Factors , Stress, Psychological/epidemiology , Surveys and Questionnaires
15.
J Bacteriol ; 191(7): 2091-101, 2009 Apr.
Article in English | MEDLINE | ID: mdl-19151138

ABSTRACT

The twin-arginine translocase (Tat) system is used by many bacteria to move proteins across the cytoplasmic membrane. Tat substrates are prefolded and contain a conserved SRRxFLK twin-arginine (RR) motif at their N termini. Many Tat substrates in Escherichia coli are cofactor-containing redox enzymes that have specific chaperones called redox enzyme maturation proteins (REMPs). Here we characterized the interactions between 10 REMPs and 15 RR peptides of known and predicted Tat-specific redox enzyme subunits. A combination of in vitro and in vivo experiments demonstrated that some REMPs were specific to a redox enzyme(s) of similar function, whereas others were less specific and bound peptides of unrelated enzymes. Results from Biacore surface plasmon resonance (SPR) and bacterial two-hybrid experiments identified interactions in addition to those found in far-Western experiments, suggesting that conformational freedom and/or other cellular factors may be required. Furthermore, we show that the interaction of the two prevents both from being proteolytically degraded in vivo, and kinetic data from SPR show up to 10-fold-tighter binding to the expected RR substrate when multiple binding partners existed. Investigations using full-length sequences of the RR proteins showed that the mature portion for some redox enzyme subunits is required for detection of the interactions. Sequence alignments among the REMPs and RR peptides indicated that homology between the REMPs and the hydrophobic regions following the RR motifs in the peptides correlates to cross-recognition.


Subject(s)
Arginine/metabolism , Escherichia coli Proteins/metabolism , Escherichia coli/metabolism , Membrane Transport Proteins/metabolism , Molecular Chaperones/metabolism , Amino Acid Motifs , Amino Acid Sequence , Escherichia coli/chemistry , Escherichia coli/genetics , Escherichia coli Proteins/chemistry , Escherichia coli Proteins/genetics , Membrane Transport Proteins/chemistry , Membrane Transport Proteins/genetics , Molecular Chaperones/chemistry , Molecular Chaperones/genetics , Molecular Sequence Data , Oxidation-Reduction , Protein Binding , Sequence Alignment , Surface Plasmon Resonance
16.
Biochim Biophys Acta ; 1778(9): 1814-38, 2008 Sep.
Article in English | MEDLINE | ID: mdl-17942072

ABSTRACT

The small multidrug resistance (SMR) protein family is a bacterial multidrug transporter family. As suggested by their title, SMR proteins are composed of four transmembrane alpha-helices of approximately 100-140 amino acids in length. Since their designation as a family, many homologues have been identified and characterized both structurally and functionally. In this review the topology, structure, drug resistance, drug binding, and transport mechanisms of the entire SMR protein family are examined. Additionally, updated bioinformatic analysis of predicted and characterized SMR protein family members was also conducted. Based on SMR sequence alignments and phylogenetic analysis of current members, we propose that this small multidrug resistance transporter family should be expanded into three subclasses: (i) the small multidrug pumps (SMP), (ii) suppressor of groEL mutation proteins (SUG), and a third group (iii) paired small multidrug resistance proteins (PSMR). The roles of these three SMR subclasses are examined, and the well-characterized members, such as Escherichia coli EmrE and SugE, are described in terms of their function and structural organization.


Subject(s)
ATP Binding Cassette Transporter, Subfamily B/classification , ATP Binding Cassette Transporter, Subfamily B/physiology , ATP Binding Cassette Transporter, Subfamily B/chemistry , ATP Binding Cassette Transporter, Subfamily B/metabolism , Amino Acid Motifs , Amino Acid Sequence , Antiporters/chemistry , Antiporters/metabolism , Antiporters/physiology , Bacterial Proteins/chemistry , Bacterial Proteins/metabolism , Bacterial Proteins/physiology , Chaperonin 60/chemistry , Chaperonin 60/metabolism , Chaperonin 60/physiology , Dimerization , Models, Biological , Models, Molecular , Molecular Weight , Phylogeny
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