Cardiac pseudoaneurysms: a clinical case series.

Background: Cardiac pseudoaneurysms are a potentially life-threatening pathology with a variety of non-specific clinical manifestations. This case series uniquely shares a collection of rare pathologies with differing preceding risk factors and presentations, with an emphasis on the utility of multi-modality imaging in diagnosis and management. Case summary: We present three cases of cardiac pseudoaneurysms. Case 1 is a 27-year-old woman with delayed presentation of a traumatic left ventricular pseudoaneurysm (LVP). Case 2 is a 73-year-old man with post-myocardial infarction LVP. Case 3 is a 38-year-old man with left ventricular outflow tract pseudoaneurysm after aortic valve replacement. Discussion: Cardiac pseudoaneurysms are rare and important to diagnose in a timely manner. Advances in non-invasive imaging modalities have improved our ability to distinguish pseudoaneurysms from other pathologies, leading to more timely management.

Better Late Than Never.

Symptomatic bradycardia may be iatrogenic or from a conduction system abnormality. Here we show an interesting case of iatrogenic symptomatic bradycardia that may be confused with a conduction system abnormality. (Level of Difficulty: Advanced.).

Ultrafast non-radiative decay of gas-phase nucleosides.

The ultrafast photo-physical properties of DNA are crucial in providing a stable basis for life. Although the DNA bases efficiently absorb ultraviolet (UV) radiation, this energy can be dissipated to the surrounding environment by the rapid conversion of electronic energy to vibrational energy within about a picosecond. The intrinsic nature of this internal conversion process has previously been demonstrated through gas phase experiments on the bases, supported by theoretical calculations. De-excitation rates appear to be accelerated when individual bases are hydrogen bonded to solvent molecules or their complementary Watson-Crick pair. In this paper, the first gas-phase measurements of electronic relaxation in DNA nucleosides following UV excitation are reported. Using a pump-probe ionization scheme, the lifetimes for internal conversion to the ground state following excitation at 267 nm are found to be reduced by around a factor of two for adenosine, cytidine and thymidine compared with the isolated bases. These results are discussed in terms of a recent proposition that a charge transfer state provides an additional internal conversion pathway mediated by proton transfer through a sugar to base hydrogen bond.

Detection limits of organic compounds achievable with intense, short-pulse lasers.

Many organic molecules have strong absorption bands which can be accessed by ultraviolet short pulse lasers to produce efficient ionization. This resonant multiphoton ionization scheme has already been exploited as an ionization source in time-of-flight mass spectrometers used for environmental trace analysis. In the present work we quantify the ultimate potential of this technique by measuring absolute ion yields produced from the interaction of 267 nm femtosecond laser pulses with the organic molecules indole and toluene, and gases Xe, N2 and O2. Using multiphoton ionization cross sections extracted from these results, we show that the laser pulse parameters required for real-time detection of aromatic molecules at concentrations of one part per trillion in air and a limit of detection of a few attomoles are achievable with presently available commercial laser systems. The potential applications for the analysis of human breath, blood and tissue samples are discussed.

A novel experimental approach to investigate radiolysis processes in liquid samples using collimated radiation sources.

Here is detailed a novel and low-cost experimental method for high-throughput automated fluid sample irradiation. The sample is delivered via syringe pump to a nozzle, where it is expressed in the form of a hanging droplet into the path of a beam of ionising radiation. The dose delivery is controlled by an upstream lead shutter, which allows the beam to reach the droplet for a user defined period of time. The droplet is then further expressed after irradiation until it falls into one well of a standard microplate. The entire system is automated and can be operated remotely using software designed in-house, allowing for use in environments deemed unsafe for the user (synchrotron beamlines, for example). Depending on the number of wells in the microplate, several droplets can be irradiated before any human interaction is necessary, and the user may choose up to 10 samples per microplate using an array of identical syringe pumps, the design of which is described here. The nozzles consistently produce droplets of 25.1 ± 0.5 µl.