Projecto Vénus - Redefinir a máquina antropológica na era da reprodutibilidade. Técnica do corpo

Desenhado por Jacque Fresco, o Projecto Vénus é uma proposta de reconfiguração social, tendo como ferramenta de trabalho a cidade. A cidade projectada por Jacque Fresco responde de alguma forma a necessidade de encontrar programas de hibridização que ultrapassem os receios do determinismo em relação ao papel da tecnologia, e conferindo um cariz mais aproximado dos conceitos antropológicos de Leroi-Gourhan quando este apelida a técnica de utensílio colocado fora do corpo e que permitiu ao homem sobreviver num mundo hostil. A diferença é que a técnica já assumiu uma condição que transcende o mero instrumento, para ser já ela própria configuradora da realidade, como Kittler dizia em acerca dos media. Fresco coloca a cidade como paradigma de uma revolução cibernética, uma tecnotopia, em que a tecnologia servirá para libertar o humano de condições políticas, económicas e sociais que o autor considera obsoletas. Uma nova configuração multidimensional que se apoia numa nova esfera pública, ambicionando um ethos global com uma estrutura digital para comunicações em rede. Fresco atribui uma dimensão de extrema importância aos factos de a tecnologia, no Projecto Vénus, ficar paredes meias com a natureza sem que tenha uma relação intrusiva, mas antes uma relação de responsabilidade pela gestão eficaz dos sistemas circundantes que preconizam muitas das “expectativas messiânicas” de que Walter Benjamin nos falava acerca da tecnologia. O objectivo da presente dissertação será a partir da definição de técnica e da tecnologia e, mais tarde discutindo esta cidade cibernética chamada Projecto Vénus, tentar responder às seguintes perguntas: como Gourhan nos diz, a técnica foi colocada fora do corpo para permitir aos seres humanos sobreviver, podemos supor que, neste momento, com a emergência de novas áreas, como a biotecnologia, nanotecnologia e robótica, a tecnologia retorna ao corpo humano para resolver a falha que, de acordo com o mito de Epimeteu, lhe deu origem? Se assim for, este processo de incorporação dos aparelhos protéticos, pode significar que estamos a entrar na era de reprodutibilidade do corpo humano como um objecto? Além disso, será a crescente visibilidade do Projecto Vénus um sintoma de uma crescente sociedade tecnológica, uma tecnotopia cujo fim último é a reconfiguração da máquina antropológica tal como Agamben colocou em «The Open»?

The use of bone bridges in transtibial amputations

We sought to describe the bone bridge technique in adults, and present a variation for use in children, as well as to present its applicability as an option in elective transtibial amputations. This paper presents a prospective study of 15 transtibial amputations performed between 1992 and 1995 in which the bone bridge technique was employed. The patients' ages ranged from 8 to 48 years, with an average of 22.5 years. This technique consisted of the preparation of a cylinder of periosteum extracted from the tibia and with cortical bone fragments attached to it to promote a tibiofibular synostosis on the distal extremity of the amputation stump. We noted that the cortical bone fragments were dispensable when the technique was employed in children, due to the increased osteogenic capacity of the periosteum. This led to a variation of the original technique, a bone bridge without the use of the cortical bone fragments. RESULTS: The average time spent with this procedure, without any significant variation between adults and children, was 171 minutes. The adaptation to the definitive prosthesis was accomplished between 20 and 576 days, with an average of 180 days. Revision of the procedure was necessary in 3 amputations. CONCLUSIONS: This technique may be employed in transtibial amputations in which the final length of the stump lies next to the musculotendinous transition of the gastrocnemius muscle, as well as in the revision of amputation stumps in children, where the procedure has been shown to be effective in the prevention of lesions due to excessive bone growth.

The Stoppa procedure in inguinal hernia repair: to drain or not to drain

OBJECTIVE: The objective of this study is to evaluate the benefits of drainage in the Stoppa procedure for inguinal repair. PATIENTS AND METHODS: The use of a suction drain was randomized at the end of the surgical intervention in 26 male patients undergoing inguinal hernia repair, divided into 2 groups: Group A, 12 patients undergoing drainage, and group B, 14 patients not undergoing drainage. On the second postoperative day, all patients underwent abdominal pelvic computed tomography scan examination to detect the presence of abdominal fluid collection. RESULTS: In group A, no patient developed fluid collection in the preperitoneal space, and 1 patient presented with an abscess in the preperitoneal space on the 15th postoperative day. In group B, 12 patients presented with fluid collections in the preperitoneal space on computed tomography scan evaluation. However, only 3 patients presented minor complications. None of the patients developed a major complication. CONCLUSION: The use of suction drainage with the Stoppa procedure does not provide any benefit.

Ag-TiNx electrodes deposited on piezoelectric poly(vinylidene fluoride) for biomedical sensor applications

Electroactive polymers are one of the most interesting class of polymers used as smart materials in various applications, such as the development of sensors and actuators for biomedical applications in areas such as smart prosthesis, implantable biosensors and biomechanical signal monitoring, among others. For acquiring or applying the electrical signal from/to the piezoelectric material, suitable electrodes can be produced from Ti based coatings with tailored multifunctional properties, conductivity and antibacterial characteristics, through Ag inclusions. This work reports on Ag-TiNx electrodes, deposited by d. c. and pulsed magnetron sputtering at room temperature on poly(vinylidene fluoride), PVDF, the all-round best piezoelectric polymer.. Composition of the electrodes was assessed by microanalysis X-ray system (EDS - energy dispersive spectrometer). The XRD results revealed that the deposition conditions preserve the polymer structure and suggested the presence of crystalline fcc-TiN phase and fcc-Ag phase in samples with N2 flow above 3 sccm. According to the results obtained from SEM analysis, the coatings are homogeneous and Ag clusters were found for samples with nitrogen flow above 3 sccm. With increasing nitrogen flow, the sheet resistivity tend to be lower than the samples without nitrogen, leading also to a decrease of the piezoelectric response. It is concluded that the deposition conditions do significantly affect the piezoelectric polymer, which maintain its characteristics for sensor/actuator applications.

Influence of saliva and mucin on the adhesion of Candida oral clinical isolates

Objectives: This research work intends to clarify the role of artificial saliva, in particularly the role of mucin, a salivary protein, on the surface properties and adhesion ability of Candida spp. oral clinical isolates to abiotic surfaces. Methods: Four oral clinical isolates of Candida spp. were used: two Candida albicans strains (AC; AM) and two Candida parapsilosis strains (AD; AM2). The strains were isolated from patients using oral prosthesis. The microorganisms were cultured in the absence or presence of mucin and artificial saliva, and their adhesion to an abiotic surface (coated with mucin and artificial saliva) was evaluated. Results: The presence of mucin per se onto the abiotic surface decreased the adhesion of all strains, although the combination of mucin with artificial saliva had reduced this effect. No direct correlation between adhesion and the surface free energies of adhesion of the microorganisms was found. Significance: Candida spp. were human commensal microorganisms that became pathogenic when the host immune defenses were compromised. Medical devices were colonized by Candida spp. particularly, oral prostheses, which might lead to the degradation of the prostheses and systemic infections. The salivary secretions that constantly cover the oral cavity influenced Candida spp. adhesion process. Therefore, it was important to understand the interactions between Candida spp., salivary proteins and the characteristic of oral prosthesis when developing materials for oral prostheses.

Accuracy comparison of implant impression techniques: A systematic review

Background Several studies link the seamless fit of implant-supported prosthesis with the accuracy of the dental impression technique obtained during acquisition. In addition, factors such as implant angulation and coping shape contribute to implant misfit. Purpose To identify the most accurate impression technique and factors affecting the impression accuracy. Material and Methods A systematic review of peer-reviewed literature was conducted analyzing articles published between 2009 and 2013. The following search terms were used: implant impression, impression accuracy, and implant misfit. A total of 417 articles was identified, 32 were selected for review. Results All 32 selected studies refer to in vitro studies. Fourteen articles compare open and closed impression technique, 8 advocate the open technique and 6 report similar results. Other 14 articles evaluate splinted and non-splinted techniques; all advocating the splinted technique. Polyether material usage was reported in 9; 6 studies tested vinyl polysiloane and 1 study used irreversible hydrocolloid. Eight studies evaluated different copings designs. Intra-oral optical devices were compared in 4 studies. Conclusions The most accurate results were achieved with two configurations: (1) the optical intra-oral system with powder; and (2) the open technique with splinted squared transfer copings, using polyether as impression material.

Biomimetic strategies to engineer mineralised human tissues

In the last few years, many reports have been describing promising biocompatible and biodegradable materials that can mimic in a certain extent the multidimensional hierarchical structure of bone, while are also capable of releasing bioactive agents or drugs in a controlled manner. Despite these great advances, new developments in the design and fabrication technologies are required to address the need to engineer suitable biomimetic materials in order tune cells functions, i.e. enhance cell-biomaterial interactions, and promote cell adhesion, proliferation, and differentiation ability. Scaffolds, hydrogels, fibres and composite materials are the most commonly used as biomimetics for bone tissue engineering. Dynamic systems such as bioreactors have also been attracting great deal of attention as it allows developing a wide range of novel in vitro strategies for the homogeneous coating of scaffolds and prosthesis with ceramics, and production of biomimetic constructs, prior its implantation in the body. Herein, it is overviewed the biomimetic strategies for bone tissue engineering, recent developments and future trends. Conventional and more recent processing methodologies are also described.

Estudo e conceção de um sistema de encaixe rápido e simples para próteses de membros inferiores

Dissertação de mestrado integrado em Engenharia Biomédica

Development of multifunctional coatings deposited on polymers based sensors for biomedical applications

Tese de Doutoramento (Programa Doutoral em Engenharia de Materiais)

Percutaneous closure of atrial septal defects. The role of transesophageal echocardiography

PURPOSE: Evaluation of the role of transesophageal echocardiography in percutaneous closure of atrial septal defects (ASD) with the Amplatzer septal occluder. METHODS: Patients were selected for percutaneous closure of ASD by transesophageal echocardiography (TEE), which was also used to monitor the procedure, helping to select the appropriate size of the Amplatzer device, to verify its position, and to access the immediate results of the procedure. During the follow-up, TEE was used to evaluate the presence and magnitude of residual shunt (RS), device position, and right cardiac chamber diameters. RESULTS: Twenty-two (40%) of a total of 55 studied patients were selected. Thirteen underwent Amplatzer device implantation, eight are still waiting for it, and one preferred the conventional surgical treatment. All procedures were successful, which was mainly due to proper patient selection. Six (23%) patients acutely developed RS, which spontaneously disapeared at the three-month follow-up examination in three patients. There was a significant reduction in the right ventricle diastolic diameter, from 27mm (average) to 24mm and 20mm, one and three months after the procedure, respectively (p<0.0076). CONCLUSION: With the aid of TEE, percutaneous closure of ASD can be successfully, safely, and effectively performed.

A new surgical approach for treating dilated cardiomyopathy with mitral regurgitation

OBJECTIVE: To evaluate the early outcome of mitral valve prostheses implantation and left ventricular remodeling in 23 patients with end-stage cardiomyopathy and secondary mitral regurgitation (NYHA class III and IV). METHODS: Mitral valvular prosthesis implantation with preservation of papillary muscles and chordae tendinae, and plasty of anteriun cuspid for remodeling of the left ventricle. RESULTS: The surgery was performed in 23 patients, preoperative ejection fraction (echocardiography) varied from 13% to 44% (median: 30%). In 13 patients associated procedures were performed: myocardial revascularization (9), left ventricle plicature repair (3) and aortic prosthese implantation (1). Early deaths (2) occurred on the 4th PO day (cardiogenic shock) and on the 20th PO day (upper gastrointestinal bleeding), and a late death in the second month PO (ventricular arrhythmia). Improvement occurred in NYHA class in 82.6% of the patients (P<0.0001), with a survival rate of 86.9% (mean of 8.9 months of follow-up). CONCLUSION: This technique offers a promising therapeutic alternative for the treatment of patients in refractory heart failure with cardiomyopathy and secondary mitral regurgitation.

Mitral valve repair with a malleable bovine pericardium ring

OBJECTIVE: To describe a surgical procedure utilizing a malleable bovine pericardium ring in mitral valve repair and clinical and echodopplercadiographic results. METHODS: Thirty-two (25 female and 7 male) patients, aged between 9 and 66 (M=36.4±17.2) years, were studied over a 16-month period, with 100% follow-up. In 23 (72%) of the patients, the mitral approach was the only one applied; 9 patients underwent associated operations. The technique applied consisted of measuring the perimeter of the anterior leaflet and implanting, according to this measurement, a flexible bovine pericardium prosthesis for reinforcement and conformation of the posterior mitral annulus, reducing it to the perimeter of the anterior leaflet with adjustment of the valve apparatus. RESULTS: The patient survival ratio was 93.8%, with 2 (6.2%) fatal outcomes, one from unknown causes, the other due to left ventricular failure. Only one reoperation was performed. On echodopplercardiography, 88% of the patients had functional recovery of the mitral valve (50% without and 38% with mild insufficiency and no hemodynamic repercussions). Of four (12%) of the remaining patients, 6% had moderate and 6% had seigre insufficiency. Twenty-eight percent of class II patients and 72% of class III patients passed into classes I (65%), II (32%), and III (3%), according to NYHA classification criteria. CONCLUSION: Being flexible, the bovine pericardium ring fit perfectly into the valve annulus, taking into account its geometry and contractility. Valve repair was shown to be reproducible, demonstrating significant advantages during patient evolution, which did not require anticoagulation measures.

Mechanical versus biological aortic valve implants in the elderly. A comparison of early and mid-term results

OBJECTIVE: Our aim was to compare, in a non randomized study, the surgical outcome in elderly patients with mechanical (Group 1; n=83) and bioprosthetic valve implants (Group 2; n=136). METHODS: During a three year period, 219 patients >75 years underwent Aortic Valve Replacement. The groups matched according to age, sex, comorbidity, valve pathology and concomitant Coronary Artery Bypass Surgery. Follow-up was a total of 469 patient-years (mean follow-up 2.1 years, maximum 4,4 years). RESULTS: Operative mortality was zero and the overall early mortality was 2.3 % (within 30 days). Actuarial survival was 87.5 ± 4.0% and 66.1 ± 7.7% (NS) at 4 years in Group 1 and Group 2, respectively. Freedom from valve-related death was 88.9 ± 3.8% in Group 1 and 69.9±7.9% (NS) in Group 2 at 4 years. CONCLUSION: Aortic Valve Replacement in the elderly (>75 years) is a safe procedure even in cases where concomitant coronary artery revascularization is performed. Only a few anticoagulant-related complications were reported and this may indicate that selected groups of elderly patients with significant life expectancy may benefit from mechanical implants .

Mitral Valve Replacement and Remodeling of the Left Ventricle in Dilated Cardiomyopathy with Mitral Regurgitation: Initial Results

OBJECTIVE: This study evaluated the effects of a new method of mitral valve replacement on left ventricular (LV) remodeling and heart failure functional class. METHODS: Eight patients (6 men) with severe mitral regurgitation from end-stage dilated cardiomyopathy underwent surgery. Five patients were in functional class (FC) IV, 2 were in FC III and 1 was in FC III/IV. Age ranged from 33 to 63 years. Both the anterior and posterior leaflets of the mitral valve were divided into hemileaflets. The resultant 4 pedicles were displaced under traction toward the left atrium and anchored between the mitral annulus and an implanted valvular prosthesis. The beating heart facilitated ideal chordae tendineae positioning. RESULTS: All patients survived and were discharged from the hospital. After a mean follow-up period of 6.5 months (1-12 m), 5 patients were in FC I; 2 in FC I/II; and 1 in FC II. The preoperative ejection fraction ranged from 19% to 30% (mean: 25.7±3.4 %), and the postoperative ejection fraction ranged from 21% to 40% (mean: 31.1± 5.8%). Doppler echocardiography showed evidence of LV remodeling in 4 patients, including lateral wall changes and a tendency of the LV cavity to return to its elliptical shape. CONCLUSION: This technique of mitral valve replacement, involving new positioning of the chordae tendineae, allowed LV remodeling and improvement in FC during this brief follow-up period.

Assessment of Thromboembolism After the Cox-Maze Procedure for Chronic Atrial Fibrillation Secondary to Mitral Valve Lesion

OBJECTIVE: To assess the occurrence of late thromboembolism after surgical repair of chronic atrial fibrillation (AF) simultaneously with repair of mitral valve using the Cox-Maze procedure. METHODS: 69 patients underwent Cox 3 procedure, with no cryoablation simultaneously with mitral valvuloplasty or prosthesis. Mean age was 49.9±13.2 years. Mean follow-up was of 31.7±19 months. Types of lesion were as follows: 33 (48%) stenoses, 23 (33%) insufficiencies, and 13 (19%) double lesions. Procedures were: 64 (93%) valvuloplasties, 3 (4%) biological and 2 (3%) mechanical prosthesis placement. There were 9 (13%) patients with previous systemic embolism and 2 (3%) had left atrial thrombi. RESULTS: Early mortality was 7% and late 1%. 2 patients (3%) were reoperated for mitral placement. At last evaluation, 10 patients (15%), were in AF. The remaining 59 (85%) were either in sinus / atrial rythm (74%) or under pacing (12%). There were no occurrence of early or late, systemic or pulmonary embolism. Permanent anticoagulation was employed in 16 cases, 10 in regular rythm and 6 in AF. The remaining 47 (75%), 2 in AF and 45 in regular rythm, did not receive anticoagulants. CONCLUSIONS: These results are in accordance with others series, where the occurrence of embolism was rare after maze procedure. Permanent systemic anticoagulation seems to be unnecessary in those cases.