High dielectric material in MRI: Numerical assessment of the reduction of the induced local power on implanted cardiac leads

High dielectric materials (HDM) have been proposed in magnetic resonance imaging (MRI) to increase the signal-to-noise ratio (SNR) of the images acquired while reducing the radiofrequency (RF) absorption in tissue. The aim of this study is to assess the potential merit of using HDM to reduce power induced at the tip of an endocardial lead in patients undergoing MRI. Numerical simulations were performed using a commercial finite-differences time-domain (FDTD) software to model the RF field generated by a birdcage body coil at 64 MHz on a human body model. Two HDM pads were placed between the coil and the body model, and their effect was evaluated in terms of local induced power at the tip of a pacemaker lead. Two different patient imaging positions inside the coil (i.e., head & thorax) were studied. In both cases, the use of HDM allowed reducing the induced power (i.e., 57% reduction with head landmark, 68% with thorax landmark), while maintaining the same magnitude of B1 RMS at the isocenter of the coil. Additionally, when the HDM pads were placed at the head landmark, there was a significant decrease in the local-induced power at the tip of the implant path (58%). Conversely, there was only a 9% decrease when pads were placed at the thorax landmark. In conclusion, the study shows that when the implant is not included in the volume surrounded by the HDM, pads placed between the RF coil and the patient allow obtaining the same magnitude of B1-field with a lower input power of the RF coil, reducing significantly the local induced power around the implant. Conversely, if the implant is included in the volume surrounded by the HDM, the use of HDM can still reduce the input power necessary to obtain the same magnitude of B1-field, but the effect on the local induce power at the implant is lower in magnitude. © 2016 IEEE

Neutron Flux Measurement at TAPIRO Fast Reactor for APD's Irradiation Fluence Evaluation

The Avalanche Photodiodes ( APD) were chosen as photon sensors for the region of the CMS electromagnetic calorimeter. The LHC will be a hard environment for what concerns the radiation levels in the detectors. The most relevant damage on APDs is caused by neutrons that produce an increase in the dark current of these devices. In the CMS-ECAL collaboration a big effort was indeed done to understand this damage, but the evaluation of the absolute effect was limited by the knowledge of the neutron flux calibration of the various irradiation facilities. This investigation describes the calibration of the neutron flux of the Tapiro reactor in Rome and the calculation of the Non-Ionizing-Energy-Loss on Silicon for this reactor. The damage parameter alpha for the APDs is evaluated to be about 10-11*10^-17 A/cm/neutron at 18C and 2 days after the irradiation. Some cross-checks with other irradiation facilities are also presented

Demography reveals populational expansion of a recently extinct Iberian ungulate

Reconstructing the demographic history of endangered taxa is paramount to predict future fluctuations and disentangle the contributing factors. Extinct taxa or populations might also provide key insights in this respect by means of the DNA extracted from museum specimens. Nevertheless, the degraded status of biological material and the limited number of records may pose some constraints. For this reason, identifying all available sources, including private and public biological collections, is a crucial step forward. In this study, we reconstructed the demographic history based on cytochrome-b sequence data of the Pyrenean ibex (Capra pyrenaica pyrenaica), a charismatic taxon of the European wildlife that became extinct in the year 2000. Moreover, we built a database of the museum specimens available in public biological collections worldwide and genotyped a privately owned 140-year-old trophy from the Spanish Pyrenees to confirm its origin. We found that the population of the Pyrenean ibex underwent a recent expansion approximately 20,000 years ago, after which trophy hunting and epizootics triggered a relentless population decline. Our interpretations, based on the genetic information currently available in public repositories, provide a solid basis for more exhaustive analyses relying on all the new sources identified. In particular, the adoption of a genome-wide approach appears a fundamental prerequisite to disentangle the multiple contributing factors associated with low genetic diversity, including inbreeding depression, acting as extinction drivers

Characterization of ANGPT2 mutations associated with primary lymphedema

Lymphedema can occur when tissue fluid cannot enter or leaks from the lymphatic system into surrounding tissues. Some genetic causes of primary lymphedema are known, but these currently explain a minority of cases. Previous studies have shown that dominant-negative mutations in angiopoietin 2 (ANGPT2), which is involved in lymphatic vessel formation and maturation, promote lymphangiogenesis in mice. Leppänen et al. now show that inactivating mutations in angiopoietin 2 associate with primary lymphedema in humans.Primary lymphedema is caused by developmental and functional defects of the lymphatic vascular system that result in accumulation of protein-rich fluid in tissues, resulting in edema. The 28 currently known genes causing primary lymphedema can explain <30% of cases. Angiopoietin 1 (ANGPT1) and ANGPT2 function via the TIE1-TIE2 (tyrosine kinase with immunoglobulin-like and epidermal growth factor–like domains 1 and 2) receptor complex and α5β1 integrin to form an endothelial cell signaling pathway that is critical for blood and lymphatic vessel formation and remodeling during embryonic development, as well as for homeostasis of the mature vasculature. By screening a cohort of 543 individuals affected by primary lymphedema, we identified one heterozygous de novo ANGPT2 whole-gene deletion and four heterozygous ANGPT2 missense mutations. Functional analyses revealed three missense mutations that resulted in decreased ANGPT2 secretion and inhibited the secretion of wild-type (WT)–ANGPT2, suggesting that they have a dominant-negative effect on ANGPT2 signaling. WT-ANGPT2 and soluble mutants T299M and N304K activated TIE1 and TIE2 in an autocrine assay in human lymphatic endothelial cells. Molecular modeling and biophysical studies showed that amino-terminally truncated ANGPT subunits formed asymmetrical homodimers that bound TIE2 in a 2:1 ratio. The T299M mutant, located in the dimerization interphase, showed reduced integrin α5 binding, and its expression in mouse skin promoted hyperplasia and dilation of cutaneous lymphatic vessels. These results demonstrate that primary lymphedema can be associated with ANGPT2 mutations and provide insights into TIE1 and TIE2 activation mechanisms.Peer reviewe

SICE national survey: current status on the adoption of laparoscopic approach to the treatment of colorectal disease in italy

The real di usion of laparoscopy for the treatment of colorectal diseases in Italy is largely unknown. The main purpose of the present study is to investigate among surgeons dedicated to minimally invasive surgery, the volume of laparoscopic colorectal procedures, the type of operation performed in comparison to traditional approach, the indication for surgery (benign and malignant) and to evaluate the di erent types of technologies used. A structured questionnaire was developed in collaboration with an international market research institute and the survey was published online; invitation to participate to the survey was issued among the members of the Italian Society of Endoscopic Surgery (SICE). 211 surgeons working in 57 surgical departments in Italy ful lled and answered the online survey. A total of 6357 colorectal procedures were recorded during the year 2015 of which 4104 (64.1%) were performed using a minimally invasive approach. Colon and rectal cancer were the most common indications for laparoscopic approach (83.1%). Left colectomy was the operation most commonly performed (41.8%), while rectal resection accounted for 23.5% of the cases. Overall conversion rate was 5.9% (242/4104). Full HD standard technology was available and routinely used in all the responders’ centers. The proportion of colorectal resec- tions that are carried out laparoscopically in dedicated centers has now reached valuable levels with a low conversion ra