Electrochemo-dynamical characterization of polypyrrole actuators coated on gold electrodes.

Polypyrrole coated gold wires were subjected to consecutive square current waves in LiClO4 aqueous solutions using the same constant anodic and cathodic charge. Parallel in situ diameter variations were followed using a laser scan micrometer. The procedure was repeated by changing one experimental variable every time: applied current, electrolyte concentration or working temperature to perform electrochemodynamical characterization of the system. On average, the diameter follows a linear variation of the consumed charge, as expected for any faradaic system, although a high dispersion was attained in the data. Such deviations were attributed to the presence of irreversible hydrogen evolution at the gold/polypyrrole interface at cathodic potentials more than 0.0 V vs. Ag/AgCl, detected and quantified from separated coulovoltammetric responses. Despite this parallel hydrogen evolution the consumed energy during reactions is a robust sensor of the working conditions. In conclusion a gold support, the metal most used for technological applications of conducting polymers, should be avoided when a device is driven by current flow in the presence of aqueous solutions, water contamination or moisture: a fraction of the charge will be consumed by hydrogen generation with possible degradation of the device.

Experience with mandibular reconstruction using transport-disc-distraction osteogenesis.

The goal of transport-disc-distraction osteogenesis (TDDO) is to restore bone continuity by using in-situ bone. It may be useful following trauma, gunshot injuries, or tumor ablation, especially when there may be contraindications at the donor site or for prolonged surgery. To the best of the authors' knowledge, this is the first time TDDO has been used for mandibular reconstruction reporting additional procedures, which include osseointegrated dental implants rehabilitation and orthognathic surgery. A retrospective study is performed analyzing all mandibular reconstruction cases that may be suitable for distraction from January 2006 to December 2011. A thorough description of the documented cases includes details about sex, gender, complications, duration of hospitalization, etiology, size, and location of the defect. Eight cases of mandibular reconstruction were included. Six cases correspond to mandibular ameloblastoma. The remaining two cases were mandibular gunshot comminuted fractures. Range of the defects was from 45 to 60 mm. Length of the transport disc was 15 to 20 mm. Protocolized technique consisted of 5 days of latency period, 19 to 45 days of activation term (average 30 days), and 8 to 12 weeks for consolidation. Mean distraction length achieved was 40.45 mm. We can conclude that TDDO is an alternative to conventional and more invasive procedures, when we face severe segmental mandibular defects reconstruction. It shows the potential to restore a better anatomical bone regeneration, also providing soft tissues and reducing donor-site morbidity. Patients' education and awareness about the proper use of the transport-disc-distraction device is important to optimize functional outcomes.

Left main bronchus rupture during video-assisted thoracoscopic surgery resection of a bronchogenic cyst.

Video-assisted thoracoscopic surgery (VATS) is an approach to resection of bronchogenic cysts (BC) which is effective and viable. There may be complications as a result of pericystic adhesions to neighboring structures during dissection. This report describes an unusual case of an operative complication, the rupture of the main left bronchus. The initial VATS approach was converted into a right thoracotomy to remove the cyst and suture the bronchus once adequate exposure was obtained. Bronchus reconstruction failed and a few hours later, it was necessary to perform a left thoracotomy. A left pneumonectomy was required after the attempt to reconstruct the anastomosis was ruled out. The conclusion is that great care should be taken when using VATS approach for BC with adhesions.

Perchlorate interchange during the redox process of PPy/PVS films in an acetonitrile medium. a voltammetric and EDX study.

Polypyrrole/poly(vinyl sulfonate) (PPy/PVS) films in acetonitrile containing 0.1 M LiClO4 were studied by cyclic voltammetry. Consecutive voltammograms pointed to a continuous increase in the charge involved in the process, suggesting a rise in the number of the electroactive participants involved in the redox process. However, voltammograms obtained for the PPy/ClO4 films in analogous conditions pointed to a steady-state behavior from the very early cycles. Theoretical studies based on the Nernst and Butler-Volmer equations indicated that perchlorate ions are involved during the oxidation/reduction process of the PPy/PVS films when the steady state is reached. This result was confirmed by "ex situ" energy-dispersive X-ray analysis of the films. In this regard, the electrochemical behavior of PPy/PVS polymers was similar to that of PPy/ClO4 films when a high number of cycles were carried out. The exchange of ClO4- during the redox reaction of the PPy/PVS films made it necessary to incorporate Li+ cations inside the polymer during the initial voltammetric cycles to compensate for the negative charges of PVS polyanions. Li+ cations are mainly stabilized inside the polymer by the ion pairs formed with the sulfonated groups of the PVS. An increase and shift of the voltammetric cycles indicated a restructuring of the polymeric chains with consecutive scans.

Molecular dynamic simulation of the hydration and diffusion of chloride ions from bulk water to polypyrrole matrix.

A molecular dynamic simulation of wet polypyrrole film was carried out, in both oxidized and reduced state. The system was modeled by two layers of polypyrrole, water and chloride ions (as counterions required for charge balance in the oxidized state) in atomic detail to provide an insight into some dynamic and steady properties of the system. Our simulations pointed to a swelling of the polymer matrix after oxidation due to electrostatic repulsions between charged sites of the oxidized polypyrrole, followed by penetration of the polypyrrole by counterions to maintain the electroneutrality of the system. Associated with this penetration of counterions toward the core of the oxidized polypyrrole, dehydration of the counterions was observed. This dehydration was compensated (in part) by a strong coordination with the charged sites of the polymer. The remaining hydrophobicity inside the polymer also contributed to the dehydration of these counterions. The translational diffusion coefficient of chloride ions was also calculated at different positions of the polypyrrole/water interface, from bulk water to the inner polymer matrix. A value of 4.1 x 10(-5) cm(2) s(-1) was measured in the bulk water compared to 5 x 10(-7) cm(2) s(-1) inside the polymer, representing a diminution of two orders of magnitude for the translational diffusion coefficient from bulk water to the core of a oxidized polypyrrole matrix. These results were in good agreement with experimental data.

Artificial muscle: movement and position control.

The movement of an all polymeric triple-layer artificial muscle based on polypyrrole (PPy) that work in aqueous solution was characterised. The magnitude and direction of the experimental current control both rate and direction of the movement. The described angle is a linear function of the consumed charge.

Nucleotide and amino acid complexity of hepatitis C virus quasispecies in serum and liver.

The quasispecies nature of the hepatitis C virus (HCV) is thought to play a central role in maintaining and modulating viral replication. Several studies have tried to unravel, through the parameters that characterize HCV circulating quasispecies, prognostic markers of the disease. In a previous work we demonstrated that the parameters of circulating viral quasispecies do not always reflect those of the intrahepatic virus. Here, we have analyzed paired serum and liver quasispecies from 39 genotype 1b-infected patients with different degrees of liver damage, ranging from minimal changes to cirrhosis. Viral level was quantified by real-time reverse transcription-PCR, and viral heterogeneity was characterized through the cloning and sequencing of 540 HCV variants of a genomic fragment encompassing the E2-NS2 junction. Although in 95% of patients, serum and liver consensus HCV amino acid sequences were identical, quasispecies complexity varied considerably between the viruses isolated from each compartment. Patients with HCV quasispecies in serum more complex (26%) than, less complex (28%) than, or similarly complex (41%) to those in liver were found. Among the last, a significant correlation between fibrosis and all the parameters that measure the viral amino acid complexity was found. Correlation between fibrosis and serum viral load was found as well (R = 0.7). With regard to the origin of the differences in quasispecies complexity between serum and liver populations, sequence analysis argued against extrahepatic replication as a quantitatively important contributing factor and supported the idea of a differential effect or different selective forces on the virus depending on whether it is circulating in serum or replicating in the liver.

[Perforation and entrapment of an intra-aortic balloon: a complication related to the duration of implantation]. / Perforación y atrapamiento de un balón intraaórtico: una complicación relacionada con el tiempo de inserción.

A 69-year-old man was admitted to the Intensive Care Recovery Unit after heart surgery, carrying an intra balloon counterpulsation (IABCP) device inserted percutaneously days before surgery to provide hemodynamic support and which was still required after surgery. Fifteen days after insertion, blood was observed in the safety chamber. Surgical removal of the catheter was required when attempts to remove it manually failed. The balloon was seen to be perforated and clotted blood was found inside. We believe that long-term maintenance of IABCP carries high risk of perforation and entry of blood, which will clot, as well as of catheter entrapment unless removal is prompt.

Transmission of hepatitis C virus by a cardiac surgeon.

BACKGROUND: In the course of a study conducted in 1992 through 1994 of the efficacy of screening blood donors for antibodies to hepatitis C virus (HCV), we found that two patients had acquired hepatitis C after cardiac surgery, with the transmission apparently unrelated to blood transfusions. Because their surgeon had chronic hepatitis C, we sought to determine whether he was transmitting the virus to his patients. METHODS: Of 222 of the surgeon's patients who participated in studies of post-transfusion hepatitis between 1988 and 1994, 6 contracted postoperative hepatitis C, despite the use of only seronegative blood for transfusions. All six patients had undergone valve-replacement surgery. Analyses were performed to compare nucleotide sequences encompassing the hypervariable region at the junction between the coding regions for envelope glycoproteins E1 and E2 in the surgeon, the patients, and 10 controls infected with the same HCV genotype. RESULTS: The surgeon and five of the six patients with hepatitis C unrelated to transfusion were infected with HCV genotype 3; the sixth patient had genotype 1 and was considered to have been infected from another source. Thirteen other patients of the surgeon had transfusion-associated hepatitis C and were also infected with genotype 1. The average net genetic distance between the sequences from the five patients with HCV genotype 3 and those from the surgeon was 2.1 percent (range, 1.1 to 2.5 percent; P < 0.001), as compared with an average distance of 7.6 percent (range, 6.1 to 8.3 percent) between the sequences from the patients and those from the controls. The results of phylogenetic-tree analysis indicated a common epidemiologic origin of the viruses from the surgeon and the five patients. CONCLUSIONS: Our findings provide evidence that a cardiac surgeon with chronic hepatitis C may have transmitted HCV to five of his patients during open-heart surgery.