Positive Selection Results in Frequent Reversible Amino Acid Replacements in the G Protein Gene of Human Respiratory Syncytial Virus

Human respiratory syncytial virus (HRSV) is the major cause of lower respiratory tract infections in children under 5 years of age and the elderly, causing annual disease outbreaks during the fall and winter. Multiple lineages of the HRSVA and HRSVB serotypes co-circulate within a single outbreak and display a strongly temporal pattern of genetic variation, with a replacement of dominant genotypes occurring during consecutive years. In the present study we utilized phylogenetic methods to detect and map sites subject to adaptive evolution in the G protein of HRSVA and HRSVB. A total of 29 and 23 amino acid sites were found to be putatively positively selected in HRSVA and HRSVB, respectively. Several of these sites defined genotypes and lineages within genotypes in both groups, and correlated well with epitopes previously described in group A. Remarkably, 18 of these positively selected tended to revert in time to a previous codon state, producing a “flip-flop” phylogenetic pattern. Such frequent evolutionary reversals in HRSV are indicative of a combination of frequent positive selection, reflecting the changing immune status of the human population, and a limited repertoire of functionally viable amino acids at specific amino acid sites

Emprego de sistemas robóticos na cirurgia cardiovascular Robotic systems in cardiovascular surgery

O desenvolvimento de sistemas robóticos para cirurgia teve início na década de 80, por solicitação do exército norte-americano, que antevia a possibilidade de realizar operações em teatros de guerra, distantes do local onde estava o cirurgião. Entretanto, o primeiro uso em humanos só ocorreu anos mais tarde, numa ressecção transuretral de hiperplasia benigna de próstata. Cirurgiões cardíacos foram logo atraídos pela técnica robótica devido a possível aplicação com reduzido caráter invasivo; esperava-se menor trauma cirúrgico e redução da dor, morbidade, tempo de internação e custo do procedimento. Atualmente, de forma restrita e em casos selecionados, robôs são usados para revascularização do miocárdio e implante de marcapasso em cirurgias cardíacas totalmente endoscópicas; podendo também constituir apoio visual na retirada de artéria torácica interna, reconstrução valvar mitral e correção de defeitos congênitos. Utilizando o robô auxiliar AESOP® para controle do videotoracoscópio, com controle vocal por meio do sistema HERMES®, temos realizado dissecção da artéria torácica interna, implante de eletrodo ventricular esquerdo e abordagem de defeitos congênitos na cirurgia de correção. Apesar do entusiasmo científico inicial com a cirurgia robótica, ainda não existe evidência clara de superioridade desta técnica em relação à operação convencional, em termos de resultado. Isto se aplica também ao custo, pois o investimento inicial na aquisição de sistema cirúrgico completo (console, controle de vídeo, instrumental) provavelmente é compensado após muitos procedimentos e longo intervalo. Mas é certo que a cirurgia robótica terá um lugar no futuro, possibilitando aprendizagem, telepresença e realização de procedimentos pouco invasivos, embora complexos.<br>The development of robotic systems for surgery started in the 80's, motivated by the US army's need for surgical procedure in field hospitals with surgeons in a distant location (tele-presence). But the first human application of robotic surgery occurred years later in a transurethral resection for benign prostatic hyperplasia. Cardiac surgeons were attracted to the robotic techniques because of the potential reduction in the invasive character of the procedures. This results in reduced trauma, a reduction of pain and morbidity, a faster recovery and lower cost of surgery. Robotic systems were developed, allowing totally thoracoscopic cardiac surgery for myocardial revascularization and multi-site pacemaker implantation in selected cases. Video-thoracoscopic support systems for internal thoracic artery harvesting, mitral valve reconstruction and correction of congenital heart defects also exist. We used the AESOP® system with HERMES® voice control to harvest the internal thoracic artery, trans-thoracic implantation of the left ventricular electrode and as an approach to congenital heart defects for surgical repair. In spite of scientific enthusiasm related to robotic surgery, there is no clear evidence of superiority of this technique when compared to conventional procedures in terms of results. The same is true with the cost of the procedures, and even if a single robotic surgery is less expensive, the initial investment for a complete robotic system (console, video control, instruments) can be compensated only with many procedures over the long term. But there is no doubt that robotic surgery will have a place in the future of surgery, providing tele-presence of the surgeon, enabling teaching and training and performing less invasive surgical procedures

Bioprótese valvar de pericárdio bovino St Jude Medical-Biocor: sobrevida tardia St Jude Medical-Biocor bovine pericardial bioprosthesis: long-term survival

OBJETIVO: Nosso objetivo é apresentar resultados a longo prazo da subsituição valvar por bioprótese de pericárdio bovino SJM-BiocorTM. MÉTODO: Entre 1992 e 2000, tiveram alta hospitalar, após substituição valvar por bioprótese de pericárdio bovino SJM-BiocorTM 304 pacientes. Idades eram de 15 a 83 anos (média: 60,6&plusmn;14,3), sendo 50,3% do sexo masculino. Pacientes tiveram situação clínica atualizada e análise atuarial foi empregada no cálculo da sobrevida simples e livre de eventos. RESULTADOS: Em um seguimento total de 931,0 pacientes-ano, ocorreram 28 (9,2%) óbitos tardios, sendo cinco (1,6%) relacionados à bioprótese, sete (2,3%) cardíacos, quatro (1,3%) não-cardíacos e 12 (3,9%) de causa desconhecida. Eventos de bioprótese foram: endocardite: 18 (5,9%), degeneração fibrocálcica: 15 (4,9%), tromboembolismo: três (1,0%), hemólise: um (0,3%). Disfunção de bioprótese resultou em 16 (5,2%) reoperações, por degeneração fibrocálcica (nove), endocardite (seis) e tromboembolismo (um). Probabilidade de sobrevida foi 86,3&plusmn;3,4%, no 5º, e 69,3&plusmn;9,0%, no 10º ano pós-operatório. Idade jovem (<40 anos, n= 35) mostrou maior sobrevida em relação à mais idosa (>60 anos, n=187): 82,0&plusmn;13,3% vs 58,8&plusmn;13,6%, no 9º ano. Sobrevida livre de eventos foi 77,5&plusmn;3,7%, no 5º, e 40,2&plusmn;9,0%, no 10º ano. Probabilidade de falência estrutural de bioprótese foi 5%, no 5º ano, e 20%, no 10º; em aórticos, zero e 8%, respectivamente. A classe funcional (NYHA) atual é I para 88,5%, II para 9,1% e III para 2,4% dos pacientes. CONCLUSÃO: Implante de bioprótese de pericárdio bovino SJM-BiocorTM resulta em satisfatória perspectiva de sobrevida dos pacientes com doença valvar e apresenta baixa prevalência de disfunção de prótese.<br>OBJECTIVE: The objective of this work is to present long-term results of valve replacement using SJM-BiocorTM bovine pericardial bioprostheses. METHODS: From 1992 to 2000, 304 patients were discharged from hospital after bioprosthesis implantation. Ages ranged from 15 to 83 years (mean: 60.6 &plusmn; 14.3 years) and 50.3% were male. Patient deaths and events related to bioprosthesis (infection, thromboembolism and structural failure) were considered for estimation of cumulative probability of survival and event-free survival. RESULTS: Total follow-up was 931.0 patients-year. During follow-up there were 28 (9.2%) deaths. Causes were bioprosthesis failure in five (1.6%), cardiac in seven (2.3%), non-cardiac in four (1.3%), and unknown in 12 (3.9%) patients. Events related to bioprosthesis were: endocarditis: 18 (5.9%), fibrocalcic degeneration: 15 (4.9%), thromboembolism: three (1.0%), hemolysis: one (0.3%). Bioprosthesis dysfunctions resulted in 16 (5.2%) reoperations due to fibrocalcic degeneration (nine), endocarditis (six) and thromboembolism (one). Probability of survival was higher in the young population (< 40 years, n=35) when compared to the older group (> 60 year, n=187): 82.0 &plusmn; 13.3% vs. 58.8 &plusmn; 13.6% in the 9th year. Event-free survival was 77.5 &plusmn; 3.7% for 5th year and 40.2 &plusmn; 9.0% for 10th year. Overall estimative of structural failure for a SJM-BiocorTM was 5% in 5th year increasing to 20% in the 10th year. In the aortic position the values were zero and 8%, respectively. Considering current clinical conditions, 88.5% are in NYHA class I, 9.1% in class II and 2.3% in class III. CONCLUSIONS: SJM-BiocorTM bovine pericardial bioprostheses resulted in satisfactory survival of patients, related to low prevalence of bioprosthesis dysfunction

Computer dynamics to evaluate blood flow through the modified Blalock-Taussig shunt

OBJECTIVES: To study the influence of geometric factors upon the function of modified Blalock-Taussig anastomoses (mBT) using a computational dynamic code based upon the method of finite elements. METHODS: The mBT operation, performed in 10 patients, was graphically reconstructed to create a parametric 3-dimensional geometric model. Using Streamline Upwind/Petrov-Galerkin approximations, blood flow and distribution were evaluated in different diameters of subclavian arteries and polytetrafluoroethylene grafts (PTFE) and angles of proximal anastomoses. RESULTS: The percentage of blood flow derived through the PTFE grows as its diameter increases in relation to subclavian artery diameter. Variations in the PTFE diameter do not interfere with pulmonary artery flow distribution. An angle of 110º in proximal anastomoses results in a high percentage of blood derivation to the graft, while angles of 30º, 60ºand 90º present with almost similar flow rates. However, angles of 30º and 110º produce an excessive flow to one of the pulmonary arteries, in detriment of the other. Peak pressure in the PTFE is affected by the proximal angle of anastomosis, with 30º resulting in higher and 110º in lower values. As the angle increases, the region of higher pressure shifts from the PTFE to subclavian artery. CONCLUSION: In the experimental model, percentage of flow derived in the PTFE is directly related to the diameter of the graft. The ratio between the diameters of subclavian artery and graft is an important regulator of flow deviation to the anastomosis. Angles of the anastomosis between the subclavian artery and the PTFE of 60º to 90º result in favorable pulmonary artery flow distribution and the location of the peak pressure