Beware of the B(e)all valve: mistaken valve identity, 30-year survival, and valve replacement

Effective management of patients after the implantation of mechanical cardiac valves includes correct recognition of each valve and its related complications. Herein, we present the case of a patient who had undergone implantation of a floating-disc Beall-Surgitool mitral valve in 1976 and developed multiple valve-related complications. Over 30 years and in multiple medical centers, the device was mistakenly assumed to be a "ball" valve. The correct identification of the prosthesis led to the recognition of valvular failure, and the patient underwent its replacement with an On-X bileaflet carbon valve. Pathologic and microscopic examination of the explanted Beall valve showed massive pannus formation that extended over the sewing cuff on the atrial and ventricular side, preventing complete disc closure; disrupted fabric coating of the sewing ring, with exposure of the underlying metal; and a marked inflammatory reaction. We report one of the longest intervals on record between the implantation and replacement of a Beall-Surgitool valve.

Biomolecular interaction analysis in functional proteomics

To understand the function of highly complex eukaryotic tissues like the human brain, in depth knowledge about cellular protein networks is required. Biomolecular interaction analysis (BIA), as a part of functional proteomics, aims to quantify interaction patterns within a protein network in detail. We used the cAMP dependent protein kinase (PKA) as a model system for the binding analysis between small natural ligands, cAMP and cAMP analogues, with their physiological interaction partner, the regulatory subunit of PKA. BIA comprises a variety of methods based on physics, biochemistry and molecular biology. Here we compared side by side real time SPR (surface plasmon resonance, Biacore), a bead based assay (AlphaScreen), a fluorescence based method (Fluorescence polarisation) and ITC (isothermal titration calorimetry). These in vitro methods were complemented by an in cell reporter assay, BRET(2) (bioluminescence resonance energy transfer), allowing to test the effects of cAMP analogues in living cells.

Advantage of three dimensional animated teaching over traditional surgical videos for teaching ophthalmic surgery: a randomised study

BACKGROUND/AIM

Owing to the complex topographical aspects of ophthalmic surgery, teaching with conventional surgical videos has led to a poor understanding among medical students. A novel multimedia three dimensional (3D) computer animated program, called "Ophthalmic Operation Vienna" has been developed, where surgical videos are accompanied by 3D animated sequences of all surgical steps for five operations. The aim of the study was to assess the effect of 3D animations on the understanding of cataract and glaucoma surgery among medical students.

METHOD

Set in the Medical University of Vienna, Department of Ophthalmology, 172 students were randomised into two groups: a 3D group (n=90), that saw the 3D animations and video sequences, and a control group (n=82), that saw only the surgical videos. The narrated text was identical for both groups. After the presentation, students were questioned and tested using multiple choice questions.

RESULTS

Students in the 3D group found the interactive multimedia teaching methods to be a valuable supplement to the conventional surgical videos. The 3D group outperformed the control group not only in topographical understanding by 16% (p<0.0001), but also in theoretical understanding by 7% (p<0.003). Women in the 3D group gained most by 19% over the control group (p<0.0001).

CONCLUSIONS

The use of 3D animations lead to a better understanding of difficult surgical topics among medical students, especially for female users. Gender related benefits of using multimedia should be further explored.

Benchmark studies of induced radioactivity produced in LHC materials, Part I: Specific activities

Samples of materials which will be used in the LHC machine for shielding and construction components were irradiated in the stray radiation field of the CERN-EU high-energy reference field facility. After irradiation, the specific activities induced in the various samples were analysed with a high-precision gamma spectrometer at various cooling times, allowing identification of isotopes with a wide range of half-lives. Furthermore, the irradiation experiment was simulated in detail with the FLUKA Monte Carlo code. A comparison of measured and calculated specific activities shows good agreement, supporting the use of FLUKA for estimating the level of induced activity in the LHC.

Comparison of synchrotron radiation calculations between analytical codes (STAC8, photon) and Monte Carlo codes (FLUKA, EGS4)

STAC8 is a significant improvement upon its predecessor PHOTON and is a valuable analytical code for quick and conservative beamline shielding designs for synchrotron radiation (SR) facilities. In order to check the applicability, accuracy and limitations of STAC8, studies were conducted to compare the results of STAC8 with those of PHOTON with calculations using the FLUKA and EGS4 Monte Carlo codes. Doses and spectra for scattered SR in a few beam-target-shield geometries were calculated, with and without photon linear polarisation effects. Areas for expanding the STAC8 capabilities, for example, features of the mirror-reflected lights and double-Compton light calculations and the use of monochromatic light have been identified. Some of these features have been implemented and benchmarked against Monte Carlo calculations. Reasonable agreements were found between the STAC8 and Monte Carlo calculations.

Benchmark studies of induced radioactivity produced in LHC materials, Part II: Remanent dose rates

A new method to estimate remanent dose rates, to be used with the Monte Carlo code FLUKA, was benchmarked against measurements from an experiment that was performed at the CERN-EU high-energy reference field facility. An extensive collection of samples of different materials were placed downstream of, and laterally to, a copper target, intercepting a positively charged mixed hadron beam with a momentum of 120 GeV c(-1). Emphasis was put on the reduction of uncertainties by taking measures such as careful monitoring of the irradiation parameters, using different instruments to measure dose rates, adopting detailed elemental analyses of the irradiated materials and making detailed simulations of the irradiation experiment. The measured and calculated dose rates are in good agreement.

Interaction effects in conductivity of Si inversion layers at intermediate temperatures

We compare the temperature dependence of resistivity rho(T) of Si-metal-oxide-semiconductor field-effect transistors with the recent theory by Zala et al. In this comparison, the effective mass m* and g* factor for mobile electrons have been determined from independent measurements. An anomalous increase of rho with temperature, which has been considered as a signature of the "metallic" state, can be described quantitatively by the interaction effects in the ballistic regime. The in-plane magnetoresistance rho(B(axially)) is only qualitatively consistent with the theory; the lack of quantitative agreement indicates that the magnetoresistance is more sensitive to sample-specific effects than rho(T).

Low-density spin susceptibility and effective mass of mobile electrons in Si inversion layers

We studied the Shubnikov-de Haas (SdH) oscillations in high-mobility Si-MOS samples over a wide range of carrier densities n approximately (1-50)x10(11) cm(-2), which includes the vicinity of the apparent metal-insulator transition in two dimensions (2D MIT). Using a novel technique of measuring the SdH oscillations in superimposed and independently controlled parallel and perpendicular magnetic fields, we determined the spin susceptibility chi(*), the effective mass m(*), and the g(*) factor for mobile electrons. These quantities increase gradually with decreasing density; near the 2D MIT, we observed enhancement of chi(*) by a factor of approximately 4.7.

Weak anisotropy and disorder dependence of the in-plane magnetoresistance in high-mobility (100) Si-inversion layers

We report studies of the magnetoresistance (MR) in a two-dimensional electron system in (100) Si-inversion layers, for perpendicular and parallel orientations of the current with respect to the magnetic field in the 2D plane. The magnetoresistance is almost isotropic; this result does not support the suggestion of its orbital origin. In the hopping regime, however, the MR contains a weak anisotropic component that is nonmonotonic in the magnetic field. We found that the field, at which the MR saturates, varies for different samples by a factor of 2 at a given carrier density. Therefore, the saturation of the MR cannot be identified with the complete spin polarization of free carriers.

Exclusion of quantum coherence as the origin of the 2D metallic state in high-mobility silicon inversion layers

The temperature and density dependence of the phase coherence time tau(phi) in high-mobility silicon inversion layers was determined from the magnetoresistivity due to weak localization. The upper temperature limit for single-electron quantum interference effects was delineated by comparing tau(phi) with the momentum relaxation time tau. A comparison between the density dependence of the borders for quantum interference effects and the strong resistivity drop reveals that these effects are not related to each other. As the strong resistivity drop occurs in the Drude regime, the apparent metallic behavior cannot be caused by quantum coherent effects.

Reisethrombose 2001

Anlässlich einer Tagung in Wien im Juni 2001 hat eine Gruppe von Experten aus Deutschland, der Schweiz und aus Österreich ein Dokument ausgearbeitet, in welchem eine Definition der Reisethrombose gegeben und Vorbeugemaßnahmen vorgeschlagen wurden, die an drei Risikogruppen angepasst sind.

CD4(+) T cell frequencies and Th1/Th2 cytokine patterns expressed in the acute and memory response to respiratory syncytial virus I-E(d)-restricted peptides

The respiratory syncytial virus (RSV)-specific frequencies and cytokine expression patterns of acute and memory CD4(+) T cells from RSV strain-A- and strain-B-infected BALB/c mice were determined following restimulation with a panel of 14 predicted RSV I-E(d) peptides from NSP-2, M, SH, F, and L proteins. Ten of fourteen peptides stimulated intracellular Th1 and/or Th2 cytokines in CD4(+) T cells from the mediastinal lymph nodes (MLN) and spleens of RSV strain-A- or strain-B-immune BALB/c mice. Spleen cells exhibited a predominant Th2 cytokine expression pattern after peptide stimulation, whereas MLN cells exhibited a mixed Th1/Th2 cytokine pattern. For a few peptides, there were differences in the Th1/Th2 cytokine response to peptides from the homologous versus heterologous RSV group. None of the 10 peptides induced both Th1 and Th2 cytokines in cells from similarly immunized mice. The frequency and breadth of cytokine expression by I-E(d)-restricted CD4(+) T cells to peptide stimulation was diminished in the memory response.

Sec61p is the main ribosome receptor in the endoplasmic reticulum of Saccharomyces cerevisiae

A characteristic feature of the co-translational protein translocation into the endoplasmic reticulum (ER) is the tight association of the translating ribosomes with the translocation sites in the membrane. Biochemical analyses identified the Sec61 complex as the main ribosome receptor in the ER of mammalian cells. Similar experiments using purified homologues from the yeast Saccharomyces cerevisiae, the Sec61p complex and the Ssh1p complex, respectively, demonstrated that they bind ribosomes with an affinity similar to that of the mammalian Sec61 complex. However, these studies did not exclude the presence of other proteins that may form abundant ribosome binding sites in the yeast ER. We now show here that similar to the situation found in mammals in the yeast Saccharomyces cerevisiae the two Sec61-homologues Sec61p and Ssh1p are essential for the formation of high-affinity ribosome binding sites in the ER membrane. The number of binding sites formed by Ssh1p under standard growth conditions is at least 4 times less than those formed by Sec61p.

Evolutionarily conserved binding of ribosomes to the translocation channel via the large ribosomal RNA

During early stages of cotranslational protein translocation across the endoplasmic reticulum (ER) membrane the ribosome is targeted to the heterotrimeric Sec61p complex, the major component of the protein-conducting channel. We demonstrate that this interaction is mediated by the 28S rRNA of the eukaryotic large ribosomal subunit. Bacterial ribosomes also bind via their 23S rRNA to the bacterial homolog of the Sec61p complex, the SecYEG complex. Eukaryotic ribosomes bind to the SecYEG complex, and prokaryotic ribosomes to the Sec61p complex. These data indicate that rRNA-mediated interaction of ribosomes with the translocation channel occurred early in evolution and has been conserved.

Plant diversity and productivity experiments in european grasslands

At eight European field sites, the impact of loss of plant diversity on primary productivity was simulated by synthesizing grassland communities with different numbers of plant species. Results differed in detail at each location, but there was an overall log-linear reduction of average aboveground biomass with loss of species. For a given number of species, communities with fewer functional groups were less productive. These diversity effects occurred along with differences associated with species composition and geographic location. Niche complementarity and positive species interactions appear to play a role in generating diversity-productivity relationships within sites in addition to sampling from the species pool.

Acquired atrial septal defect as a complication of endocarditis--a case report

Bacterial endocarditis predominantly involves cardiac valves and is associated with many potential complications. Valvular dysfunction resulting from disruption of the structural integrity of valves are not infrequent. This report illustrates a rare case of endocarditis involving the interatrial septum which subsequently produced destruction of the structure resulting in an acquired atrial septal defect.

[Discovery of the cardiac effectiveness of cinchona bark and its alkaloids]

The cardiac side effects of chinchona bark were discovered very soon after its introduction to the materia medica of academic medicine towards the end of the 17th century (Georg Ernst Stahl, 1660-1734). Therapeutically these effects were utilized sporadically as early as in the first half of the 18th century (Gerhard van Swieten, 1700-1772; John Wall, 1708-1776; William Saunders, 1743-1817). Purified quinine became a standard component of cardiac therapy in the 2nd half of the 19th century (Ludwig Traube, 1818-1876; Johann Oppolzer, 1808-1871; Karel Frederik Wenckebach, 1864-1940). In 1918 quinidine was introduced by Walter Frey (1884-1972) as the common alkaloid of chinchona bark and is still used in rhythmology today.

Discrimination between antibodies to HIV-1 and HIV-2 in sera from northern Zaire

136 selected sera from Northern Zaire were screened for antibodies against HIV-1 and HIV-2 using the ELISA method. Reactive sera were confirmed with commercially available Western Blots and additional tests. A data base was used for evaluation of the results. The sera were collected in the town Isiro and in remote rural areas. 36 sera were reactive in the HIV-1 ELISA (ELAVIA-1), 19 of them were confirmed in the HIV-1 Western Blot (Biorad). 21 sera were reactive in the HIV-2 ELISA, but they were not confirmed as HIV-2-specific in three HIV-2 Western Blots (Diagnostics Pasteur, Biorad, Paul-Ehrlich-Institut).