Ventricular fibrillation occurring after atrioventricular node ablation despite minimal difference between pre- and post-ablation heart rates

We report the case of an 82-year-old man presenting with ventricular fibrillation (VF) occurring acutely after atrioventricular node (AVN) ablation. This patient had severe valvular cardiomyopathy, chronic atrial fibrillation (AF), and underwent prior to the AVN ablation a biventricular implantable cardiac defibrillator positioning. The VF was successfully cardioverted with one external electrical shock. What makes this presentation original is that the pre-ablation spontaneous heart rate in AF was slow (84 bpm), and that VF occurred after ablation despite a minimal heart rate drop of only 14 bpm. VF is the most feared complication of AVN ablation, but it had previously only been described in case of acute heart rate drop after ablation of at least 30 bpm (and more frequently>50 bpm). This case report highlights the fact that VF may occur after AVN ablation regardless of the heart rate drop, rendering temporary fast ventricular pacing mandatory whatever the pre-ablation heart rate.

Assessing the Risk of Sarcopenia in the Elderly: The Mini Sarcopenia Risk Assessment (MSRA) Questionnaire

OBJECTIVES

to validate the MSRA questionnaire proposed as prescreening tool for sarcopenia, in a population of community-dwelling elderly subjects.

DESIGN

observational study.

SETTING

community dwelling elderly subjects.

PARTICIPANTS

274 community dwelling elderly subjects, 177 women and 97 men, aged 66-78 years.

MEASUREMENTS

Based on EWGSOP diagnostic criteria subjects were classified as sarcopenic and non-sarcopenic. The Mini Sarcopenia Risk Assessment (MSRA) questionnaire, is composed of seven questions and investigates anamnestic and nutritional characteristics related to risk of sarcopenia onset (age, protein and dairy products consumption, number of meals per day, physical activity level, number of hospitalizations and weight loss in the last year).

RESULTS

33.5% of the study population, were classified as sarcopenic. With the 7-item MSRA score, subjects with a score of 30 or less, had a 4-fold greater risk of being sarcopenic than subjects with a score higher than 30 (OR:4.20;95% CI:2.26-8.06); area under the ROC curve was 0.786 (95% CI:0.725-0.847). In a logistic regression, considering as dependent variable the probability of being sarcopenic, and as independent variables the 7 items of the questionnaire, two items (number of meals and milk and dairy products consumption) showed non-significant diagnostic power. A 5-item score was then derived and the area under the ROC curve was 0.789 (95% IC:0.728-0.851). Taking into account the cost of false positive and false negative costs and the prevalence of sarcopenia, the "optimal" threshold of the original MSRA score (based on 7 items) is 30, with a sensitivity of 0.804 and a specificity of 0.505, while the "optimal" threshold of the MSRA score based on 5 items, is 45, with a sensitivity of 0.804 and a specificity of 0.604.

CONCLUSION

this preliminary study shows that the MSRA questionnaire is predictive of sarcopenia and can be suggested as prescreening instrument to detect this condition. The use of a short form of the MSRA questionnaire improves the capacity to identify sarcopenic subjects.

Slow Interatomic Coulombic Decay of Multiply Excited Neon Clusters

Ne clusters (∼5000  atoms) were resonantly excited (2p→3s) by intense free electron laser (FEL) radiation at FERMI. Such multiply excited clusters can decay nonradiatively via energy exchange between at least two neighboring excited atoms. Benefiting from the precise tunability and narrow bandwidth of seeded FEL radiation, specific sites of the Ne clusters were probed. We found that the relaxation of cluster surface atoms proceeds via a sequence of interatomic or intermolecular Coulombic decay (ICD) processes while ICD of bulk atoms is additionally affected by the surrounding excited medium via inelastic electron scattering. For both cases, cluster excitations relax to atomic states prior to ICD, showing that this kind of ICD is rather slow (picosecond range). Controlling the average number of excitations per cluster via the FEL intensity allows a coarse tuning of the ICD rate.

A novel treatment of cystic fibrosis acting on-target: cysteamine plus epigallocatechin gallate for the autophagy-dependent rescue of class II-mutated CFTR

This corrects the article DOI: 10.1038/cdd.2016.22.

A novel treatment of cystic fibrosis acting on-target: cysteamine plus epigallocatechin gallate for the autophagy-dependent rescue of class II-mutated CFTR

We previously reported that the combination of two safe proteostasis regulators, cysteamine and epigallocatechin gallate (EGCG), can be used to improve deficient expression of the cystic fibrosis transmembrane conductance regulator (CFTR) in patients homozygous for the CFTR Phe508del mutation. Here we provide the proof-of-concept that this combination treatment restored CFTR function and reduced lung inflammation (P<0.001) in Phe508del/Phe508del or Phe508del/null-Cftr (but not in Cftr-null mice), provided that such mice were autophagy-competent. Primary nasal cells from patients bearing different class II CFTR mutations, either in homozygous or compound heterozygous form, responded to the treatment in vitro. We assessed individual responses to cysteamine plus EGCG in a single-centre, open-label phase-2 trial. The combination treatment decreased sweat chloride from baseline, increased both CFTR protein and function in nasal cells, restored autophagy in such cells, decreased CXCL8 and TNF-α in the sputum, and tended to improve respiratory function. These positive effects were particularly strong in patients carrying Phe508del CFTR mutations in homozygosity or heterozygosity. However, a fraction of patients bearing other CFTR mutations failed to respond to therapy. Importantly, the same patients whose primary nasal brushed cells did not respond to cysteamine plus EGCG in vitro also exhibited deficient therapeutic responses in vivo. Altogether, these results suggest that the combination treatment of cysteamine plus EGCG acts 'on-target' because it can only rescue CFTR function when autophagy is functional (in mice) and improves CFTR function when a rescuable protein is expressed (in mice and men). These results should spur the further clinical development of the combination treatment.

Investigation into local cell mechanics by atomic force microscopy mapping and optical tweezer vertical indentation

Investigating the mechanical properties of cells could reveal a potential source of label-free markers of cancer progression, based on measurable viscoelastic parameters. The Young's modulus has proved to be the most thoroughly studied so far, however, even for the same cell type, the elastic modulus reported in different studies spans a wide range of values, mainly due to the application of different experimental conditions. This complicates the reliable use of elasticity for the mechanical phenotyping of cells. Here we combine two complementary techniques, atomic force microscopy (AFM) and optical tweezer microscopy (OTM), providing a comprehensive mechanical comparison of three human breast cell lines: normal myoepithelial (HBL-100), luminal breast cancer (MCF-7) and basal breast cancer (MDA-MB-231) cells. The elastic modulus was measured locally by AFM and OTM on single cells, using similar indentation approaches but different measurement parameters. Peak force tapping AFM was employed at nanonewton forces and high loading rates to draw a viscoelastic map of each cell and the results indicated that the region on top of the nucleus provided the most meaningful results. OTM was employed at those locations at piconewton forces and low loading rates, to measure the elastic modulus in a real elastic regime and rule out the contribution of viscous forces typical of AFM. When measured by either AFM or OTM, the cell lines' elasticity trend was similar for the aggressive MDA-MB-231 cells, which were found to be significantly softer than the other two cell types in both measurements. However, when comparing HBL-100 and MCF-7 cells, we found significant differences only when using OTM.

Multicolor High-Gain Free-Electron Laser Driven by Seeded Microbunching Instability

Laser-heater systems are essential tools to control and optimize high-gain free-electron lasers (FELs) working in the x-ray wavelength range. Indeed, these systems induce a controllable increase of the energy spread of the electron bunch. The heating suppresses longitudinal microbunching instability which otherwise would limit the FEL performance. Here, we demonstrate that, through the action of the microbunching instability, a long-wavelength modulation of the electron beam induced by the laser heater at low energy can persist until the beam entrance into the undulators. This coherent longitudinal modulation is exploited to control the FEL spectral properties, in particular, multicolor extreme-ultraviolet FEL pulses can be generated through a frequency mixing of the modulations produced by the laser heater and the seed laser in the electron beam. We present an experimental demonstration of this novel configuration carried out at the FERMI FEL.

Single Shot Polarization Characterization of XUV FEL Pulses from Crossed Polarized Undulators

Polarization control is a key feature of light generated by short-wavelength free-electron lasers. In this work, we report the first experimental characterization of the polarization properties of an extreme ultraviolet high gain free-electron laser operated with crossed polarized undulators. We investigate the average degree of polarization and the shot-to-shot stability and we analyze aspects such as existing possibilities for controlling and switching the polarization state of the emitted light. The results are in agreement with predictions based on Gaussian beams propagation.

Long-term outcome on kidney retransplantation: a review of 100 cases from a single center

Renal transplantation has become an effective form of treatment for end-stage renal failure. Unfortunately, as a consequence of immunological and nonimmunological pathogenic mechanisms, chronic allograft nephropathy is responsible for the loss of a large proportion of kidney grafts after several years and return to dialysis. We have reported herein our 24 years of experience with second kidney transplantations. Of 1,302 kidney transplantations between January 1983 and June 2007 performed in our transplantation center, 100 were second transplantations. Kidney retransplantation was performed in 74 men and 26 women of overall mean age of 35.4 +/- 12.6 years. Cadaveric donor grafts were transplanted in 92 patients, whereas the remaining 8 were living-related donor kidneys. At 1, 5, and 10 years after kidney transplantation, patient survival rates were 100%, 96%, and 92%, respectively, whereas graft survival rates were 85%, 72%, and 53%, respectively. Immunosuppressive therapy included induction therapy with polyclonal anti-lymphocyte antibodies (ALG/ATG) or (starting from 1999) monoclonal anti CD 25 antibody. Our results demonstrated good outcomes for kidney retransplantations with allocation based on anti- HLA antibody identification together with induction immunosuppression.

The FERMI free-electron lasers

FERMI is a seeded free-electron laser (FEL) facility located at the Elettra laboratory in Trieste, Italy, and is now in user operation with its first FEL line, FEL-1, covering the wavelength range between 100 and 20 nm. The second FEL line, FEL-2, a high-gain harmonic generation double-stage cascade covering the wavelength range 20-4 nm, has also completed commissioning and the first user call has been recently opened. An overview of the typical operating modes of the facility is presented.

Experimental demonstration of enhanced self-amplified spontaneous emission by an optical klystron

We report the first experimental evidence of enhancement of self-amplified spontaneous emission, due to the use of an optical klystron. In this free-electron laser scheme, a relativistic electron beam passes through two undulators, separated by a dispersive section. The latter converts the electron-beam energy modulation produced in the first undulator in density modulation, thus enhancing the free-electron laser gain. The experiment has been carried out at the FERMI facility in Trieste. Powerful radiation has been produced in the extreme ultraviolet range, with an intensity a few orders of magnitude larger than in pure self-amplified spontaneous emission mode. Data have been benchmarked with an existing theoretical model.

Magnetization and microstructure dynamics in Fe/MnAs/GaAs(001): Fe magnetization reversal by a femtosecond laser pulse

Thin film magnetization reversal without applying external fields is an attractive perspective for applications in sensors and devices. One way to accomplish it is by fine-tuning the microstructure of a magnetic substrate via temperature control, as in the case of a thin Fe layer deposited on a MnAs/GaAs(001) template. This work reports a time-resolved resonant scattering study exploring the magnetic and structural properties of the Fe/MnAs system, using a 100 fs optical laser pulse to trigger local temperature variations and a 100 fs x-ray free-electron laser pulse to probe the induced magnetic and structural dynamics. The experiment provides direct evidence that a single optical laser pulse can reverse the Fe magnetization locally. It reveals that the time scale of the magnetization reversal is slower than that of the MnAs structural transformations triggered by the optical pulse, which take place after a few picoseconds already.

Listening to speech recruits specific tongue motor synergies as revealed by transcranial magnetic stimulation and tissue-Doppler ultrasound imaging

The activation of listener's motor system during speech processing was first demonstrated by the enhancement of electromyographic tongue potentials as evoked by single-pulse transcranial magnetic stimulation (TMS) over tongue motor cortex. This technique is, however, technically challenging and enables only a rather coarse measurement of this motor mirroring. Here, we applied TMS to listeners' tongue motor area in association with ultrasound tissue Doppler imaging to describe fine-grained tongue kinematic synergies evoked by passive listening to speech. Subjects listened to syllables requiring different patterns of dorso-ventral and antero-posterior movements (/ki/, /ko/, /ti/, /to/). Results show that passive listening to speech sounds evokes a pattern of motor synergies mirroring those occurring during speech production. Moreover, mirror motor synergies were more evident in those subjects showing good performances in discriminating speech in noise demonstrating a role of the speech-related mirror system in feed-forward processing the speaker's ongoing motor plan.

Impact of non-Gaussian electron energy heating upon the performance of a seeded free-electron laser

Laser-heater systems have been demonstrated to be an important component for the accelerators that drive high gain free electron laser (FEL) facilities. These heater systems suppress longitudinal microbunching instabilities by inducing a small and controllable slice energy spread to the electron beam. For transversely uniform heating, the energy spread augmentation is characterized by a non-Gaussian distribution. In this Letter, we demonstrate experimentally that in addition to suppression of the microbunching instability, the laser heater-induced energy distribution can be preserved to the FEL undulator entrance, significantly impacting the performance of high-gain harmonic generation (HGHG) FELs, especially at soft x-ray wavelengths. In particular, we show that the FEL intensity has several local maxima as a function of the induced heating caused by the non-Gaussian energy distribution together with a strong enhancement of the power at high harmonics relative to that expected for an electron beam with an equivalent Gaussian energy spread at an undulator entrance. These results suggest that a single stage HGHG FEL can produce scientifically interesting power levels at harmonic numbers m ≥ 25 and with current seed laser technology could reach output photon energies above 100 eV or greater.

Experimental demonstration of electron longitudinal-phase-space linearization by shaping the photoinjector laser pulse

Control of the electron-beam longitudinal-phase-space distribution is of crucial importance in a number of accelerator applications, such as linac-driven free-electron lasers, colliders and energy recovery linacs. Some longitudinal-phase-space features produced by nonlinear electron beam self- fields, such as a quadratic energy chirp introduced by geometric longitudinal wakefields in radio-frequency (rf) accelerator structures, cannot be compensated by ordinary tuning of the linac rf phases nor corrected by a single high harmonic accelerating cavity. In this Letter we report an experimental demonstration of the removal of the quadratic energy chirp by properly shaping the electron beam current at the photoinjector. Specifically, a longitudinal ramp in the current distribution at the cathode linearizes the longitudinal wakefields in the downstream linac, resulting in a flat electron current and energy distribution. We present longitudinal-phase-space measurements in this novel configuration compared to those typically obtained without longitudinal current shaping at the FERMI linac.