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1.
World J Pediatr Congenit Heart Surg ; : 21501351241237091, 2024 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-38715391

RESUMO

Background: Pulmonary autograft failure remains a cause of reoperation following the Ross procedure. The aim of this study is to describe our evolving approach to autograft reoperations. Methods: Retrospective study of all patients who underwent a pulmonary autograft reoperation following a Ross procedure between June 1997 and July 2022. Results: Two-hundred and thirty-five Ross procedures were performed. Thirty-six patients (15%) plus one referral underwent an autograft reoperation at a median of 7.8 years (IQR 4.6-13.6). The main indication was: neoaortic root dilatation associated with mild/moderate (n = 12) or severe (n = 8) aortic regurgitation; isolated severe aortic regurgitation (n = 6); infective endocarditis (IE) (n = 8); and aortic root pseudoaneurysm with no history of IE (n = 3). The autograft was spared in 29 cases (78%): 9 patients (24%) underwent aortic valve repair or aortic root remodeling, 15 patients (40%) aortic root reimplantation, 5 patients neoaortic root stabilization with a Personalized External Aortic Root Support (PEARS) sleeve. There were no in-hospital deaths. At a median follow up of 37 months (IQR 8-105), all patients were alive, 30 (81%) were asymptomatic. Eight patients (22%) required nine further reoperations. Estimated freedom from further reoperation was 90%, 72%, and 72% at 12-, 36-, and 60-months. Conclusions: Autograft reoperations following the Ross procedure can be safely performed and do not affect overall survival in the early and mid-term. Valve-sparing autograft replacement is technically feasible but remains at risk of further interventions. Alternative strategies, such as the PEARS sleeve, are becoming increasingly available but requires validation in the long term.

2.
J Wound Care ; 32(8): 520-526, 2023 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-37572337

RESUMO

Right ventricular rupture after deep sternal wound infection (DSWI) is a rare but fatal complication, and can occur with or without vacuum assisted closure (VAC) therapy. There is currently no strong evidence to suggest whether or not VAC therapy is a contributing factor to this complication. In total, 30 articles were retrieved and assessed through a systematic review strategy from 1953 to 2022. The keywords: 'vacuum assisted closure'; 'VAC'; 'negative pressure wound therapy'; 'deep sternal wound infection'; 'DSWI'; 'right ventricular rupture'; and 'cardiac rupture' were used in the search. Overall, 15 of the included articles satisfied the predefined eligibility criteria. Fatal right ventricular ruptures were reported in 18 (36%) out of 50 cases. In this article, the risk factors, mechanisms and management of right ventricular rupture are discussed. A novel view of the mechanism of VAC-associated right ventricular rupture is highlighted, with a focus on both pre- and intraoperative management.

3.
Eur J Cardiothorac Surg ; 63(1)2022 12 02.
Artigo em Inglês | MEDLINE | ID: mdl-36165691

RESUMO

OBJECTIVES: Contemporarily modified Ross procedure continues to deliver excellent outcomes and remains part of the treatment strategy for aortic valve disease in the young adult population. The aim of this study was to assess whether Ross procedure carried out as a second or subsequent intervention for aortic valve disease carries similar risk and long-term benefit, when compared to Ross procedure for the first-time aortic valve replacement. METHODS: A total of 158 patients aged 16-60 years from a single congenital cardiac centre between 1997 and 2020 were included. The sample was split into 2 subgroups, based on the history of previous aortic valve interventions prior to the Ross procedure. Primary outcomes were defined as survival and pulmonary autograft failure. Coarsened exact matching was used to balance for covariates. RESULTS: A total of 103 patients underwent primary Ross and 55 underwent secondary Ross with a mean follow-up of 7.8 years. Twenty-two patients underwent 28 reoperations during follow-up. Forty-nine well-matched pairs were obtained through matching. Freedom from pulmonary autograft failure at 10 years was 84.5% in the primary group vs 100% in the secondary group (P = 0.021). Five- and ten-year survival were identical, 97.5% in the primary group vs 95.6% in the secondary group (P = 0.53). Male sex and era were found to be predictors of neoaortic root dilatation. CONCLUSIONS: The lower incidence of graft failure seen in secondary Ross could justify a stepwise approach to aortic valve intervention. Ross procedure delivers excellent outcomes in the adult population with no difference in survival for primary or secondary Ross.


Assuntos
Insuficiência da Valva Aórtica , Estenose da Valva Aórtica , Valva Pulmonar , Adulto Jovem , Humanos , Masculino , Valva Aórtica/cirurgia , Autoenxertos , Transplante Autólogo/efeitos adversos , Insuficiência da Valva Aórtica/cirurgia , Estenose da Valva Aórtica/cirurgia , Reoperação/efeitos adversos , Valva Pulmonar/transplante , Resultado do Tratamento , Seguimentos , Estudos Retrospectivos
4.
Surgeon ; 20(5): 321-327, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34600827

RESUMO

BACKGROUND: Chest drains are placed after surgery to enable lung re-expansion. However, there remains little guidance on optimal placement. This study aims to identify the ideal size and position for chest drain insertion with regards to post-operative outcomes. METHODS: 383 patients undergoing lobectomy in 1-year had their chest drain size and x-ray position noted (1 (apical), 2 (mid-zone) or 3 (basal)). Primary outcome was residual air space on immediate post-operative x-ray. Secondary outcomes were length of drain in situ (<72 versus ≥72 h), persisting pleural effusion, surgical emphysema, post-operative pneumonia (POP), and length of hospital stay (<5 versus ≥5 days). Fisher's exact analysis for the primary outcome and binary logistic regression analysis for all outcomes were used. Results presented as odds ratios (OR±95%CI). RESULTS: Univariate analysis for residual air space showed increased risk in area 2 (OR = 1.61, p = 0.041) and 3 (OR = 2.59, p = 0.0043) compared with area 1. Multivariate analysis for residual air space showed increased risk in area 2 (OR = 2.39, p < 0.001) and 3 (OR = 2.86, p < 0.001) compared with area 1. Drain size had no impact on residual air space in univariate or multivariate analysis. Multivariate analysis showed area 2 drains remained in situ for >72 h (OR = 1.49, p = 0.017), had persisting effusions (OR = 2.03, p = 0.004) and POP (OR = 2.10, p = 0.023) compared with area 1. This risk is magnified further for drains in area 3. Drains ≥28F had reduced risk of surgical emphysema (OR = 0.23, p = 0.027) in multivariate analysis. CONCLUSION: A ≥28F, apical chest drain reduces the risk of post-operative complications, allowing early removal and discharge.


Assuntos
Tubos Torácicos , Enfisema , Drenagem/métodos , Humanos , Tempo de Internação , Pulmão , Complicações Pós-Operatórias/epidemiologia , Complicações Pós-Operatórias/etiologia , Complicações Pós-Operatórias/prevenção & controle
5.
Aorta (Stamford) ; 9(5): 190-192, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34879401

RESUMO

With both stenosis and aneurysm, repairing a severely tortuous and coarcted aorta can present certain difficulties. The advent of hybrid arch frozen elephant trunk techniques, as well as other endovascular solutions, has produced safer surgical repair methods for such cases. We present the reconstruction and repair of a Type-1 thoracoabdominal aortic aneurysm using a staged approach in less-than-optimal anatomy. Interventions included hybrid frozen elephant trunk, balloon dilation, and thoracic endovascular repair.

6.
JTCVS Open ; 5: 17-25, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-34172983

RESUMO

OBJECTIVE: The coronavirus disease 2019 (COVID-19) pandemic has posed challenges to health care services across the world. There has been a significant restructuring of health care resources to protect services for patients with COVID-19-related illness and to maintain emergency and urgent medical and surgical activity. This study assessed access to emergency treatment, logistical challenges, and outcomes of patients with acute aortic syndrome during the early months of the COVID-19 pandemic in the United Kingdom. METHODS: This was a multicenter study, from March 1 to May 20, 2020 that included 19 cardiac centers, was a retrospective analysis of prospectively collected data obtained from individual centers' national cardiac surgical databases. Demographic details, choice of treatment, operative details, and outcomes were collected. COVID-19 screening, timing of surgery, and outcomes of COVID-19-positive and -negative patients were also analyzed. RESULTS: In total, 88 patients presented with acute aortic syndrome to participating centers from March 1 to May 20, 2020. There were 79 aortic dissections (89.8%), 7 intramural hematomas (7.9%), and 2 penetrating aortic ulcers (2.3%). Seventy-nine patients (89.8%) underwent surgery. In-hospital mortality was 25.3% (n = 20). Postoperative complications included 13.9% postoperative stroke (11.4% permanent and 2.3% temporary), 16.5% rate of hemofiltration, and 10.1% rate of tracheostomy. Nine patients were treated conservatively with a mortality of 60%. Seven patients were diagnosed with COVID-19, and there was no associated mortality. CONCLUSIONS: Despite extensive restructuring of health care resources, access to emergency and urgent treatment for patients with acute aortic syndrome was maintained in the early months of the COVID-19 pandemic in the United Kingdom. Clinical outcomes were similar to the prepandemic period.

7.
J Card Surg ; 36(8): 2692-2696, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33982333

RESUMO

OBJECTIVE: The coronavirus disease (COVID-19) increases the respiratory complications and carries a higher mortality in the immediate postoperative period. The aim of this study was to analyze the outcomes of patients with type A acute aortic syndromes (AAS) diagnosed with COVID-19 in the perioperative period. METHODS: Retrospective analysis of prospectively collected data between March and August 2020 from 20 participating cardiac surgery centers in the United Kingdom. RESULTS: Among 122 patients who underwent emergency surgical repair for type A AAS at the participating centers, 3 patients (2.5%) tested positive for COVID-19 in the preoperative screeing, and 4 cases turned to be positive in the postoperative period having been operated on an unknown COVID-19 status. Another patient was diagnosed of COVID-19 disease based on radiological features. These eight patients had increased postoperative complications, including respiratory failure, longer ventilation times, and Intensive Therapy Unit (ITU) stay and increased mortality when compared with COVID-19 negative patients. CONCLUSION: COVID-19 disease in the perioperative period of type A AAS poses a challenge. Despite the increasing morbidity and mortality associated with the virus, the prognosis of the aortic disease is poorer and emergency surgery should not be contraindicated based on the COVID-19 diagnosis alone.


Assuntos
Teste para COVID-19 , COVID-19 , Humanos , Complicações Pós-Operatórias/epidemiologia , Estudos Retrospectivos , SARS-CoV-2 , Síndrome , Reino Unido/epidemiologia
8.
Ann Vasc Surg ; 75: 120-127, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33905848

RESUMO

OBJECTIVE: The COVID-19 pandemic has forced the cancellation of planned surgery and led to significant surgical service reductions. Early intervention in aortovascular disease is often critical and cannot be deferred despite these reductions. There is urgent need to evaluate the provision and outcomes of thoracic aortovascular intervention during the peak of the pandemic. METHODS: Prospective data was collected for patients receiving open and endovascular thoracic aortovascular intervention over two-time points; January-May 2020 and January-May 2019 at three tertiary cardiovascular centres. Baseline demographics, cardiovascular risk and COVID-19 screening results were noted. Primary outcomes were median length of intensive care unit and hospital stay, intra-operative mortality, 30-day mortality, post-operative stroke, and spinal cord injury. RESULTS: Patients operated in 2020 (41) had significantly higher median EuroSCORE II than 2019 (53) (7.44 vs. 5.86, P = 0.032) and rates of previous cardiac (19.5% vs. 3.8%, P = 0.019), aortic (14.6% vs. 1.9%, P = 0.041), and endovascular (22.0% vs. 3.8%, P = 0.009) intervention. There was an increase in proportion of urgent cases in 2020 (31.7% vs. 18.9%). There were no intra-operative deaths in 2020 and 1 in 2019 (P = 1.00). There were no significant differences (P ≥ 0.05) in 30-day mortality (4.9% vs. 13.2%), median intensive care unit length of stay (72 vs. 70 hr), median hospital length of stay (8 vs. 9 days), post-operative stroke (3 vs. 6), or spinal cord injury (2 vs. 1) between 2020 and 2019 respectively. CONCLUSIONS: Despite the increased mortality risk of patients and urgency of cases during COVID-19, complicated by the introduction of cohorting and screening regimens, thoracic aortovascular intervention remained safe with comparable in outcomes to pre-COVID-19.


Assuntos
Aorta Torácica/cirurgia , Doenças da Aorta/cirurgia , COVID-19 , Procedimentos Cirúrgicos Vasculares , Idoso , Idoso de 80 Anos ou mais , Aorta Torácica/diagnóstico por imagem , Doenças da Aorta/diagnóstico por imagem , Doenças da Aorta/mortalidade , COVID-19/diagnóstico , COVID-19/mortalidade , COVID-19/prevenção & controle , COVID-19/transmissão , Teste para COVID-19 , Bases de Dados Factuais , Inglaterra , Feminino , Mortalidade Hospitalar , Humanos , Tempo de Internação , Masculino , Pessoa de Meia-Idade , Segurança do Paciente , Complicações Pós-Operatórias/etiologia , Estudos Prospectivos , Medição de Risco , Fatores de Risco , Fatores de Tempo , Resultado do Tratamento , Procedimentos Cirúrgicos Vasculares/efeitos adversos , Procedimentos Cirúrgicos Vasculares/mortalidade
9.
J Card Surg ; 36(3): 848-856, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33442890

RESUMO

BACKGROUND: A significant restructuring of the healthcare services has taken place since the declaration of the coronavirus disease 2019 (COVID-19) pandemic, with elective surgery put on hold to concentrate intensive care resources to treat COVID-19 as well as to protect patients who are waiting for relatively low risk surgery from exposure to potentially infected hospital environment. METHODS: Multicentre study, with 19 participating centers, to define the impact of the pandemic on the provision of aortovascular services and patients' outcomes after having adapted the thresholds for intervention to guarantee access to treatment for emergency and urgent conditions. Retrospective analysis of prospectively collected data, including all patients with aortovascular conditions admitted for surgical or conservative treatment from the 1st March to the 20th May 2020. RESULTS: A total of 189 patients were analyzed, and 182 underwent surgery. Diagnosis included: aneurysm (45%), acute aortic syndrome (44%), pseudoaneurysm (4%), aortic valve endocarditis (4%), and other (3%). Timing for surgery was: emergency (40%), urgent (34%), or elective (26%). In-hospital mortality was 12%. Thirteen patients were diagnosed with COVID-19 during the peri-operative period, and this subgroup was not associated with a higher mortality. CONCLUSIONS: There was a significant change in service provision for aortovascular patients in the UK. Although the emergency and urgent surgical activity were maintained, elective treatment was minimal during early months of the pandemic. The preoperative COVID-19 screening protocol, combined with self-isolation and shielding, contributed to the low incidence of COVID-19 in our series and a mortality similar to that of pre-pandemic outcomes.


Assuntos
Doenças da Aorta/cirurgia , COVID-19/epidemiologia , Emergências , Pandemias , SARS-CoV-2 , Procedimentos Cirúrgicos Vasculares/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Doenças da Aorta/epidemiologia , Comorbidade , Serviço Hospitalar de Emergência , Feminino , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Reino Unido/epidemiologia
10.
Ann Thorac Surg ; 112(1): e37-e39, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33412138

RESUMO

The use of continuous-flow mechanical circulatory support in preschool children remains anecdotal. This case report describes the sequel to the implantation with a HeartWare HVAD system (Medtronic, Minneapolis, MN) in a 3-year old child. A 3-year-old boy with myocarditis-related cardiomyopathy underwent implantation with a HeartWare device. After an uncomplicated postoperative course, the patient was discharged home. Serial echocardiography showed progressive left ventricular recovery. After 6 months, the device was decommissioned, and the outflow graft was tied off. Six years after insertion, the device was explanted uneventfully. The HeartWare ventricular assist device offers viable long-term mechanical circulatory support in selected children that results in sustainable care and good quality of life.


Assuntos
Remoção de Dispositivo/métodos , Previsões , Insuficiência Cardíaca/cirurgia , Ventrículos do Coração/cirurgia , Coração Auxiliar/efeitos adversos , Qualidade de Vida , Recuperação de Função Fisiológica , Pré-Escolar , Ecocardiografia , Seguimentos , Insuficiência Cardíaca/diagnóstico , Ventrículos do Coração/diagnóstico por imagem , Ventrículos do Coração/fisiopatologia , Humanos , Masculino
11.
Eur J Surg Oncol ; 46(10 Pt A): 1882-1887, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32847696

RESUMO

OBJECTIVES: The IASLC 8th TNM Staging 8th differentiates between a greater number of T-stages. Resection remains the mainstay of curative treatment with often significant waiting times. This study aims to quantify the T-stage progression and growth of non-small cell lung cancers (NSCLCs) between radiological diagnosis and resection, and its impact on disease recurrence and survival. MATERIALS AND METHODS: A retrospective analysis of NSCLC resections (289) in a high-volume centre between July 01, 2015 and June 30, 2016. Baseline demographics, time from diagnostic CT to surgery, tumour size (cm) and T-stage from diagnostic CT, PET-CT and post-operative histopathology reports were recorded. The primary outcome was increase in T-stage from diagnostic CT to resection. Kaplan-Meier and cox proportional hazard analyses were used to determine recurrence-free survival and survival. RESULTS: Median increase in tumour size between diagnosis and resection was 0.3 cm (p < 0.0001). Median percentage increase in size was 13%. T-stage increased in 133 (46.0%) patients. N stage increased in 51 patients (17.7%), 32 (11.1%) to N2 disease. Mean survival in those upstaged was 43.5 (39.9-47.1) months versus 53.4 (50.0-56.8) months in patients not upstaged (p = 0.025). Mean recurrence-free survival in those upstaged was 39.1 (35.2-43.0) months versus 47.7 (43.9-51.4) months in patients not upstaged (p = 0.117). Upstaging was independently associated with inferior survival (HR 1.674, p = 0.006) and inferior recurrence-free survival (HR 1.423, p = 0.038). CONCLUSIONS: A significant number of patients are upstaged between diagnostic and resection resulting in reduced survival and recurrence-free survival. A change in management pathways are required to improve outcomes in NSCLC.


Assuntos
Adenocarcinoma de Pulmão/patologia , Carcinoma Pulmonar de Células não Pequenas/patologia , Carcinoma de Células Escamosas/patologia , Neoplasias Pulmonares/patologia , Linfonodos/patologia , Tempo para o Tratamento , Adenocarcinoma de Pulmão/cirurgia , Idoso , Idoso de 80 Anos ou mais , Carcinoma Pulmonar de Células não Pequenas/diagnóstico por imagem , Carcinoma Pulmonar de Células não Pequenas/cirurgia , Carcinoma de Células Escamosas/diagnóstico por imagem , Carcinoma de Células Escamosas/cirurgia , Quimioterapia Adjuvante , Progressão da Doença , Intervalo Livre de Doença , Feminino , Humanos , Neoplasias Pulmonares/diagnóstico por imagem , Neoplasias Pulmonares/cirurgia , Excisão de Linfonodo , Linfonodos/diagnóstico por imagem , Linfonodos/cirurgia , Masculino , Margens de Excisão , Pessoa de Meia-Idade , Invasividade Neoplásica , Estadiamento de Neoplasias , Pneumonectomia , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Estudos Retrospectivos , Taxa de Sobrevida , Tomografia Computadorizada por Raios X , Carga Tumoral
12.
Scott Med J ; 64(2): 67-70, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30373501

RESUMO

INTRODUCTION: Dropped gallstones are gallstones lost in the abdominal cavity during cholecystectomy. They are a rare occurrence and often cause minimal long-term issues. However, it is recognised that dropped stones can cause intra- or extra-abdominal sepsis. We present three cases below which highlight this. CASES: All three cases describe patients presenting for laparoscopic cholecystectomy, Cases 1 and 2 post-gallstone pancreatitis and Case 3 for gallbladder stones. Cases 1 and 3 presented nine months and five years post-operatively, respectively, with flank abscess. Both received CT scans, with incision and drainage performed to remove gallstone. Case 2 presented six weeks post-operatively with cough and breathlessness. CT scan showed pleural effusion with communication to subphrenic collection. Pus and gallstone fragments were drained. CONCLUSION: The above cases highlight that despite the majority of patients remaining asymptomatic, dropped gallstones should be considered amongst the differential in patients presenting with intra- or extra-abdominal abscess post-cholecystectomy, with timely intervention key to management.


Assuntos
Parede Abdominal , Abscesso/etiologia , Colecistectomia Laparoscópica/efeitos adversos , Empiema Pleural/etiologia , Corpos Estranhos/complicações , Cálculos Biliares/complicações , Idoso , Idoso de 80 Anos ou mais , Feminino , Cálculos Biliares/cirurgia , Humanos , Masculino , Pessoa de Meia-Idade
13.
Scott Med J ; 63(1): 3-10, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29073846

RESUMO

Background Immunosuppression helps prevent acute rejection post-cardiac transplant but has been linked to malignancy development. This may be due to a reduction in T-lymphocyte function, a direct oncogenic effect or the increased impact of environmental carcinogens. There has been shown to be significant increases in non-melanoma skin cancers and post-transplant lympho-proliferative disorders, particularly in those treated with OKT3. Aim To investigate the survival and incidence of malignancy in the Scottish cardiac transplant population and whether rates of non-melanoma skin cancers justify the provision of specialist dermatological follow-up. Methods and results Retrospective case note analysis of patients transplanted (363) or followed up (2) in Scotland from 1992 to 2016. Kaplan-Meier survival analysis generated a survival curve. Patients had a 1-year survival of 82% and a median survival of 10.9 years. There were 60 (95% CI 47.5, 75.2) NMSCs and 8 (3.7, 12.4) post-transplant lympho-proliferative disorders diagnosed in the cohort (3110 person years follow-up). Fisher's exact test was employed to analyse the association between induction therapy (via OKT3 or rabbit antithymocyte globulin) and post-transplant lympho-proliferative disorder development. Patients treated with OKT3 had a 6.7 times greater risk ( P = 0.014) and a shorter experience of patients treated with rabbit antithymocyte globulin has so far shown no significantly altered risk ( P = 1.00) of developing a post-transplant lympho-proliferative disorder. Conclusion Incidences of non-melanoma skin cancers and post-transplant lympho-proliferative disorders were increased in the Scottish cardiac transplant population and there was a significant association between post-transplant lympho-proliferative disorder development and OKT3 therapy but not rabbit antithymocyte globulin therapy. These findings in Scottish patients reflect what is published in wider literature and support the provision of a dedicated post-transplant dermatology clinic.


Assuntos
Rejeição de Enxerto/prevenção & controle , Transplante de Coração , Terapia de Imunossupressão , Imunossupressores/efeitos adversos , Transtornos Linfoproliferativos/induzido quimicamente , Neoplasias Cutâneas/induzido quimicamente , Seguimentos , Rejeição de Enxerto/imunologia , Humanos , Terapia de Imunossupressão/efeitos adversos , Incidência , Estimativa de Kaplan-Meier , Transtornos Linfoproliferativos/imunologia , Transtornos Linfoproliferativos/mortalidade , Transtornos Linfoproliferativos/patologia , Complicações Pós-Operatórias/imunologia , Complicações Pós-Operatórias/mortalidade , Estudos Retrospectivos , Escócia/epidemiologia , Neoplasias Cutâneas/imunologia , Neoplasias Cutâneas/mortalidade , Neoplasias Cutâneas/patologia , Linfócitos T/imunologia
14.
Ecol Evol ; 5(15): 3103-13, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26357539

RESUMO

Toxicity and the utilization of venom are essential features in the ecology of many animal species and have been hypothesized to be important factors contributing to the assembly of communities through competitive interactions. Ants of the genus Monomorium utilize a variety of venom compositions, which have been reported to give them a competitive advantage. Here, we investigate two pairs of Monomorium species, which differ in the structural compositions of their venom and their co-occurrence patterns with the invasive Argentine ant. We looked at the effects of Monomorium venom toxicity, venom utilization, and aggressive physical interactions on Monomorium and Argentine ant survival rates during arena trials. The venom toxicity of the two species co-occurring with the invasive Argentine ants was found to be significantly higher than the toxicity of the two species which do not. There was no correlation between venom toxicity and Monomorium survival; however, three of the four Monomorium species displayed significant variability in their venom usage which was associated with the number of Argentine ant workers encountered during trials. Average Monomorium mortality varied significantly between species, and in Monomorium smithii and Monomorium antipodum, aggressive interactions with Argentine ants had a significant negative effect on their mortality. Our study demonstrates that different factors and strategies can contribute to the ability of a species to withstand the pressure of a dominant invader at high abundance, and venom chemistry appears to be only one of several strategies utilized.

15.
J Am Chem Soc ; 137(7): 2452-5, 2015 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-25668687

RESUMO

We report the highly enantioselective addition of photogenerated α-amino radicals to Michael acceptors. This method features a dual-catalyst protocol that combines transition metal photoredox catalysis with chiral Lewis acid catalysis. The combination of these two powerful modes of catalysis provides an effective, general strategy to generate and control the reactivity of photogenerated reactive intermediates.


Assuntos
Aminas/química , Ácidos de Lewis/química , Processos Fotoquímicos , Catálise , Radicais Livres/química , Oxirredução , Estereoisomerismo
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