Electrochemical characterization and in-vitro bio-assessment of AZ31B and AZ91E alloys as biodegradable implant materials.

The degradation of magnesium alloys, AZ31B and AZ91E, are under review due to a their ability to degrade under physiological conditions and successively yield an oxidized biocompatible by-product which can safely be absorbed by the body. By exploiting the biodegradability of magnesium alloys, the prospects of developing an unprecedented class of implant are at hand. To do so however, the rate of corrosion of the alloys must be modified in order to better suit physiological conditions. Therefore, anodization was carried out on AZ31B and AZ91E specimens to alter the surface chemistry to reduce the corrosion rates and improve biocompatibility. Scanning electron microscopy, energy dispersive spectroscopy, atomic force microscopy and contact angle meter, were used to characterize and compare the surfaces of untreated and anodized magnesium alloys. Corrosion behavior was evaluated by electrochemical tests using potentiodynamic polarization and electrochemical impedance spectroscopy, to verify changes in corrosion rates as a result of anodization. Finally, a bio-assessment using MTS assays and fluorescent microscopy were carried out to ensure that the anodization process had no compromise on the biocompatibility of the magnesium alloys. The study indicated that the anodization process did alter the surface chemistry of the alloys, yielding slower corrosion rates, while causing no adverse effects in regards to biocompatibility.

In vitro evaluation of hyperosmotic canine plasma suitable for infusion.

OBJECTIVE: To determine the characteristics of canine freeze-dried plasma (cFDP) as it is serially diluted with sterile water. DESIGN: In vitro experimental study. SETTING: Government blood and coagulation research laboratory. ANIMALS: cFDP from a commercial manufacturer. INTERVENTIONS: Ten units of cFDP were reconstituted to 100%, 90%, 80%, 70%, 60%, 50%, and 40% of the recommended volume with sterile water. The resultant solutions were analyzed for coagulation factor activity (factors II, V, VII, VIII, IX, X, and XII as well as antithrombin), fibrinogen concentration, prothrombin time, activated partial thromboplastin time, viscosity, osmolality, and kaolin-activated thromboelastography. MEASUREMENTS AND MAIN RESULTS: Viscosity, osmolality, and turbidity properties of plasma were increased in a reconstitution volume-dependent manner, with the 40% suggested volume generating approximately 2-fold increases in each. Similarly, factor activity levels and fibrinogen concentration increased by approximately 2-fold over this range in a concentration-dependent manner. Prothrombin time declined from 11.4 seconds at 100% volume to 10.9 seconds at 70% before increasing to 11.9 seconds at 40%. Activated partial thromboplastin time increased exponentially from 21.8 seconds at 100% rehydration to 100.0 seconds at 40%. R-time on TEG increased from 3.1 to 13.9 minutes at 50% rehydration, while alpha angle declined from 61.3° to 24.7° over the same range, and the maximum amplitude initially increased from 13.2 mm at 100% water to 18.6 mm at 70% water before dropping back down to 14.6 mm at 50% water. No clotting was observed with 40% rehydration. CONCLUSIONS: The creation of hyperosmotic plasma from cFDP appears feasible with preservation of concentrated coagulation factors, although there are some unexplained effects that happen to coagulation functions at the highest concentrations tested using only 40%-50% of recommended rehydration volume. Further studies are needed to evaluate the hyperosmotic product in vivo.

Electrochemical & osteoblast adhesion study of engineered TiO2 nanotubular surfaces on titanium alloys.

TiO2 nanotubes were grafted on the surface of cpTi, Ti6Al4V and Ti6Al4V-ELI with the aim to provide a new podium for human pre-osteoblast cell (MC3T3) adhesion and proliferation. The surface morphology and chemistry of these alloys were examined with scanning electron microscopy and energy dispersive x-ray spectroscopy. TiO2 nanotubes were further characterized by cyclic potentiodynamic polarization tests and electrochemical impedance spectroscopy. The vertically aligned nanotubes were subjected to pre-osteoblast cell proliferation in order to better understand cell-material interaction. The study demonstrated that these cells interact differently with nanotubes of different titanium alloys. The significant acceleration in the growth rate of pre-osteoblast cell adhesion and proliferation is also witnessed. Additionally, the cytotoxicity of the leached metal ions was evaluated by using a tetrazolium-based bio-assay, MTS. Each group of data was operated for p<0.05, concluded one way ANOVA to investigate the significance difference.

[Hemorrhagic pericarditis and cardiac tamponade in systemic lupus erythematosus. A case report]. / Reporte de un caso depericarditis hemorrágica y taponamiento cardíaco asociados a lupus eritematoso sistémico.

Systemic lupus erythematosus is a chronic inflammatory autoimmune disorder that can affect any organ or system. Although pericarditis is the most frequent cardiac manifestation of this entity, usually is not a life threatening situation. Pericardial effusion causing cardiac tamponade is a very rare complication in lupus, with an incidence less than 2%. We report a case of pericardial tamponade due to SLE with severe hemodynamic involvement in a 21-year-old woman associated to rapidly progressive glomerulonephritis, acute pancreatitis, acute acalculous cholecystitis, pleural effusion, hematologic, cutaneous and neurologic lupus activity. Recognition of this rare manifestation of SLE may be life saving.

Surface characterization and cytotoxicity response of biodegradable magnesium alloys.

Magnesium alloys have raised an immense amount of interest to many researchers because of their evolution as a new kind of third generation materials. Due to their biocompatibility, density, and mechanical properties, magnesium alloys are frequently reported as prospective biodegradable implant materials. Moreover, magnesium alloys experience a natural phenomenon to biodegrade in aqueous solutions due to its corrosion activity, which is excellent for orthopedic and cardiovascular applications. However, a major concern with such alloys is fast and non-uniform corrosion degradation. Controlling the degradation rate in the physiological environment determines the success of biodegradable implants. In this investigation, three different grades of magnesium alloys: AZ31B, AZ91E and ZK60A were studied for their corrosion resistance and biocompatibility. Scanning electron microscopy, energy dispersive spectroscopy, atomic force microscopy and contact angle meter are used to study surface morphology, chemistry, roughness and wettability, respectively. Additionally, the cytotoxicity of the leached metal ions was evaluated by using a tetrazolium based bio-assay, MTS.

Pheochromocytoma-induced acute pulmonary edema and reversible catecholamine cardiomyopathy mimicking acute myocardial infarction.

Acute noncardiogenic pulmonary edema and catecholamine-induced cardiomyopathy as the first presentations of pheochromocytoma are uncommon events, but usually rapidly fatal. A 36-year-old man presented acute pulmonary edema in a setting of hypertensive emergency after arthroscopy, later developing catecholamine-induced cardiotoxicity mimicking an acute myocardial infarction, with elevation of cardiac damage markers, normal coronary arteries, and with full recovery from electrical abnormalities. Magnetic resonance imaging revealed a right adrenal mass. Elevated levels of catecholamines and metanephrines, and a positive 131I-metaiodobenzylguanidine scan confirmed a pheochromocytoma. Once the patient had been hemodynamically stabilized, he was successfully operated.

[Care for the cardiopathy patient after percutaneous coronary intervention]. / Cuidados del paciente cardiópata tras una intervención coronaria percutánea.

At present, new indications and frontiers of interventional cardiology led to percutaneous treatment of a wide spectrum of patients who require myocardial revascularization. The physician must understand the potential benefits, procedural characteristics, and risks of percutaneous coronary intervention. In this paper, we review general concepts concerning coronary angioplasty.

Reporte de un caso de pericarditis hemorrágica y taponamiento cardíaco asociados a lupus eritematoso sistémico / Hemorrhagic pericarditis and cardiac tamponade in systemic lupus erythematosus. A case report

El lupus eritematoso sistémico es una enfermedad autoinmune inflamatoria capaz de afectar cualquier aparato y sistema. Aunque la pericarditis es la manifestación cardíaca más frecuentemente observada, usualmente no es una situación que comprometa la vida del paciente. El taponamiento cardíaco ocasionado por derrame pericárdico en el lupus es una situación extremadamente rara, con una incidencia no mayor al 2%. Informamos el caso de una mujer de 21 años de edad con taponamiento cardíaco por lupus eritematoso sistémico, asociado a glomerulonefritis rápidamente progresiva, pancreatitis aguda, colecistitis aguda acalculosa, derrame pleural y actividad lúpica hematológica, cutánea y neurológica. El reconocimiento oportuno de esta rara manifestación del lupus puede salvar la vida de un paciente.

Systemic lupus erythematosus is a chronic inflammatory autoimmune disorder that can affect any organ or system. Although pericarditis is the most frequent cardiac manifestation of this entity, usually is not a life threatening situation. Pericardial effusion causing cardiac tamponade is a very rare complication in lupus, with an incidence less than 2%. We report a case of pericardial tamponade due to SLE with severe hemodynamic involvement in a 21-year-old woman associated to rapidly progressive glomerulonephritis, acute pancreatitis, acute acalculous cholecystitis, pleural effusion, hematologic, cutaneous and neurologic lupus activity. Recognition of this rare manifestation of SLE may be life saving.

Cuidados del paciente cardiópata tras una intervención coronaria percutánea / Care for the Cardiopathy Patient after Percutaneous Coronary Interventions

En la actualidad, las indicaciones y alcances de la cardiología intervencionista permiten que cada vezmás pacientes puedan ser revascularizados mediante intervenciones coronarias percutáneas. Es esencial para los médicos que están en contacto o tienen a su cargo el cuidado de estos pacientes conocer los beneficios, características y riesgos del procedimiento. En este trabajo revisamos los conceptos generales actuales de la angioplastía coronaria.

At present, new indications and frontiers of interventional cardiology led to percutaneous treatment of a wide spectrum of patients who require myocardial revascularization. The physician must understand the potential benefits, procedural characteristics, andrisks of percutaneous coronary intervention. In this paper, we review general concepts concerning coronary angioplasty.