Which way in? The necessity of multiple approaches to transcatheter valve therapy

TAVI (transcatheter aortic valve implantation) is a less invasive treatment of the stenotic aortic valve while avoiding midline sternotomy and cardiopulmonary bypass. A crimped biological valve on a self-expanding or balloonexpandable stent is inserted antegradely or retrogradely under fluoroscopy, and deployed on the beating heart. Among the worldwide TAVI programs, many different concepts have been established for the choice of the access site. Whether retrograde or antegrade TAVI should be considered the superior approach is matter of an ongoing debate. The published literature demonstrates safety of all techniques if performed within a dedicated multidisciplinary team. Since there is no data providing evidence if one approach is superior to another, we conclude that an individualized patient-centered decision making process is most beneficial, taking advantage of the complementarity of the different access options. The aim of this article is to give an overview of the current practice of access techniques for transcatheter based valve treatment and to outline the respective special characteristics.

Pressure shift freezing as potential alternative for generation of decellularized scaffolds

Background. Protocols using chemical reagents for scaffold decellularization can cause changes in the properties of the matrix, depending on the type of tissue and the chemical reagent. Technologies using physical techniques may be possible alternatives for the production grafts with potential superior matrix characteristics. Material and Methods. We tested four different technologies for scaffold decellularization. Group 1: high hydrostatic pressure (HHP), 1 GPa; Group 2: pressure shift freezing (PSF); Group 3: pulsed electric fields (PEF); Group 4: control group: detergent (SDS). The degree of decellularization was assessed by histological analysis and the measurement of residual DNA. Results. Tissue treated with PSF showed a decellularization with a penetration depth (PD) of 1.5 mm and residual DNA content of 24% ± 3%. HHD treatment caused a PD of 0.2 mm with a residual DNA content of 28% ± .4%. PD in PEF was 0.5 mm, and the residual DNA content was 49% ± 7%. In the SDS group, PD was found to be 5 mm, and the DNA content was determined at 5% ± 2%. Conclusion. PSF showed promising results as a possible technique for scaffold decellularization. The penetration depth of PSF has to be optimized, and the mechanical as well as the biological characteristics of decellularized grafts have to be evaluated.

Automation of an extracorporeal support system with adaptive fuzzy controllers

For patients suffering from cardiogenic shock cardiopulmonary resuscitation may not be sufficient to restore normal heart function. However, their chances of survival may be increased with the use of an extracorporeal support system. With this system the patient's organs are perfused while being transported to the nearest hospital for proper treatment. In the automation of an extracorporeal support system the patient's vital signals are constantly monitored and proper adjustments are performed to improve organ perfusion. In this paper, an adaptive fuzzy controller is proposed that uses the knowledge and expertise of a perfusionist as a starting point and reference for regulation. Furthermore it is able to adapt to the patient's specific reactions by manipulating the rule base of the fuzzy controller. The performance of the adaptive fuzzy controller is tested with a simulation model of the cardiovascular system.

Design of a fuzzy controller for the automation of an extracorporeal support system with the use of a simulation environment

The automation of a portable extracorporeal support system may greatly help people who suffer from cardiogenic shock by providing them with an optimal oxygen perfusion and avoid mult-organ failure while being transported to a hospital. This however requires the creation of tools that help in the design of the ideal controller. In this paper a simulation environment is described were a cardiovascular model from the ISR Physiome database was used together with a model of a portable extracorporeal support system. Additionally a model of an oxygenator/blender model is introduced to allow the simulation of oxygen perfusion. Fuzzy controlling was used for automation since it allows a straightforward implementation of expert knowledge. Through the simulation environment different scenarios may be created where intensive testing is possible and constant repetition for control optimization. Initial simulation results are given of the fuzzy controller adjusting the extracorporeal flow rate and oxygen administration for a case of low cardiac output.

Right ventricular fibroma in a 61-year-old man

We report on a 61-year-old man who presented with new negative T-waves in V3 to V5. Coronary heart disease with a nonsignificant stenosis of the anterior interventricular artery was known for three years without any symptoms of heart failure. Harvested endomyocardial biopsies of the left ventricle during catheterization showed a chronic parvovirus B19-associated myocarditis. A magnetic resonance imaging was carried out and showed a 6 x 3 x 3-cm mass in the right ventricle extending from the apex. The tumor could be completely resected using cardiopulmonary bypass. Histopathological diagnosis was consistent with a benign fibroma.

Measurement and modeling of pulsed microchannel plate operation (invited)

Microchannel plates (MCPs) are a standard detector for fast-framing x-ray imaging and spectroscopy of high-temperature plasmas. The MCP is coated with conductive striplines that carry short duration voltage pulses to control the timing and amplitude of the signal gain. This gain depends on the voltage to a large exponent so that small reflections or impedance losses along the striplines can have a significant impact on the position-dependent amplitude and pulse width of the gain. Understanding the pulsed gain response therefore requires careful measurements of the position- and time-dependent surface voltage coupled with detailed modeling of the resulting electron cascade. We present measurements and modeling of the time- and space-dependent gain response of MCP detectors designed for use at Sandia National Laboratories' Z facility. The pulsed gain response is understood through measurements using a high impedence probe to determine the voltage pulse propagating along the stripline surface. Coupling the surface voltage measurements with Monte Carlo calculations of the electron cascade in the MCP provides a prediction of the time- and position-dependent gain that agrees with measurements made on a subpicosecond UV laser source to within the 25% uncertainty in the simulations.

Surfactant protein D in serum from patients with allergic bronchopulmonary aspergillosis

Surfactant protein D (SP-D) interacts with Aspergillus fumigatus and is strongly increased in the lavage from animals with acute allergic reactions to the fungus, suggesting a central role for SP-D. As the course of cystic fibrosis (CF) is often complicated by an allergic bronchopulmonary aspergillosis (ABPA), the authors hypothesised that SP-D may also be increased in serum during an ABPA, potentially assisting in its diagnosis and follow-up. In 22 patients with CF (11 with ABPA, 11 matched without ABPA) and 19 control patients without a pulmonary disease, SP-D concentrations in serum were assessed by an enzyme immunoassay. Serum SP-D in CF patients (130 +/- 16 ng x mL(-1) (mean +/- SEM)) was significantly higher than in the controls without lung disease (66 +/- 8 ng x mL(-1)). During the whole ABPA-episode, SP-D level did not change significantly, despite large changes of total serum immunoglobulin E. There was a clear negative correlation between SP-D concentration and overall lung function, i.e. forced expiratory volume in one second and forced vital capacity. Serum level of surfactant protein D may be of value to follow pulmonary function and lung injury in cystic fibrosis patients. Surfactant protein D serum levels are not helpful for the diagnosis and follow-up of an allergic bronchopulmonary aspergillosis episode, contrary to what was expected from animal experiments.

Study on the surface of resins that burn without residues in the lost-wax procedure

STATEMENT OF PROBLEM

When compared with waxes and prefabricated components made of dental alloys, processing resins is difficult and often results in a less accurate fit. The exact linear dimension is hard to realize, as the materials required for a dental casting are adjusted to dental waxes, and usually there are no special processing instructions for these resins.

PURPOSE

The surface structure of 16 residue-free burning resins was determined to find which could enlarge the range of application for waxes in the dental casting technique.

MATERIAL AND METHODS

A total of 480 specimens (30 castings for each of 16 resins) were marked with an individually cut pyramid, which left an impression in the resin. This was distinctly visible in the metal after casting in "the lost form." The surfaces of these 480 specimens were measured in three dimensions with a positioning aid "before casting in resin" and "after casting in metal" by the Perthometer micrometer. All specimens were treated identically by the lost-wax process by using the rotation symmetry of the muffle. The differences in the surface data before casting in resin and after casting in metal characterize the quality of the particular resin.

RESULTS

Surface roughness differed between the 16 resins in the range of micrometer.

CONCLUSIONS

With the dental casting technique, it is recommended that some resins replace waxes or wax-resin compositions.

In vitro production of monoclonal antibodies in high concentration in a new and easy to handle modular minifermenter

This paper describes a new and easy to handle reusable minifermenter for high-density culture of hybridoma and other cells. The culture apparatus is composed of two modules: a 40 ml disposable cell culture and antibody production chamber (the 'production module') and a 550 ml medium reservoir (the 'supply module'). The two modules are separated from each other by a dialysis membrane allowing passage of low molecular mass nutrients and metabolites. The monoclonal antibodies are produced and enriched in the production module. The outer part of this module is made from a thin gas-permeable silicone rubber membrane allowing exchange of gases (oxygen and carbon dioxide). To start the culture, the cells are injected into the production module through ports in the silicone rubber which are equipped with Luer Lock connectors. Samples can be removed in the same way. For culturing, the minifermenter is rolled on a roller apparatus in a carbon dioxide-supplied incubator. Depending on the individual properties of the hybridoma cells cultured, cell densities of more than 10 x 10(6) (in some cases up to 35 x 10(6)) cells per ml and monoclonal antibody concentrations of several mg per ml can be obtained in the new minifermenter. On average, 61 mg (range: 9-159 mg) could be produced within 1-4 weeks. In terms of their properties the monoclonal antibodies produced in the new modular minifermenter were indistinguishable from antibodies prepared from ascitic fluid or from the supernatant of conventional stationary culture. The culture method is a useful alternative to the in vivo production method in mice. In addition, it represents a completely new, inexpensive and easy to handle general solution to the problem of culturing cells in high density and obtaining cellular products in high concentrations.