Abstract
A fast and reliable range monitoring method is required to take full advantage of the high linear energy transfer provided by therapeutic ion beams like carbon and oxygen while minimizing ...damage to healthy tissue due to range uncertainties. Quasi-real-time range monitoring using in-beam positron emission tomography (PET) with therapeutic beams of positron-emitters of carbon and oxygen is a promising approach. The number of implanted ions and the time required for an unambiguous range verification are decisive factors for choosing a candidate isotope. An experimental study was performed at the FRS fragment-separator of GSI Helmholtzzentrum für Schwerionenforschung GmbH, Germany, to investigate the evolution of positron annihilation activity profiles during the implantation of
$$^{14}$$
14
O and
$$^{15}$$
15
O ion beams in a PMMA phantom. The positron activity profile was imaged by a dual-panel version of a Siemens Biograph mCT PET scanner. Results from a similar experiment using ion beams of carbon positron-emitters
$$^{11}$$
11
C and
$$^{10}$$
10
C performed at the same experimental setup were used for comparison. Owing to their shorter half-lives, the number of implanted ions required for a precise positron annihilation activity peak determination is lower for
$$^{10}$$
10
C compared to
$$^{11}$$
11
C and likewise for
$$^{14}$$
14
O compared to
$$^{15}$$
15
O, but their lower production cross-sections make it difficult to produce them at therapeutically relevant intensities. With a similar production cross-section and a 10 times shorter half-life than
$$^{11}$$
11
C,
$$^{15}$$
15
O provides a faster conclusive positron annihilation activity peak position determination for a lower number of implanted ions compared to
$$^{11}$$
11
C. A figure of merit formulation was developed for the quantitative comparison of therapy-relevant positron-emitting beams in the context of quasi-real-time beam monitoring. In conclusion, this study demonstrates that among the positron emitters of carbon and oxygen,
$$^{15}$$
15
O is the most feasible candidate for quasi-real-time range monitoring by in-beam PET that can be produced at therapeutically relevant intensities. Additionally, this study demonstrated that the in-flight production and separation method can produce beams of therapeutic quality, in terms of purity, energy, and energy spread.
Here we report the isolation and characterization of three metagenome-derived clones that interfere with bacterial quorum sensing and degrade N-(3-oxooctanoyl)-L-homoserine lactone (3-oxo-C₈-HSL). By ...using a traI-lacZ gene fusion, the metagenome-derived clones were identified from a soil DNA library and analyzed. The open reading frames linked to the 3-oxo-C₈-HSL-degrading activities were designated bpiB01, bpiB04, and bpiB07. While the BpiB07 protein was similar to a known lactonase, no significant similarities were observed for the BpiB01 and BpiB04 proteins or the deduced amino acid sequences. High-performance liquid chromatography-mass spectrometry analyses confirmed that the identified genes encode novel lactone-hydrolyzing enzymes. The original metagenome-derived clones were expressed in Pseudomonas aeruginosa and employed in motility and biofilm assays. All clones were able to reproducibly inhibit motility in P. aeruginosa. Furthermore, these genes clearly inhibited biofilm formation in P. aeruginosa when expressed in P. aeruginosa PAO1. Thus, this is the first study in which metagenome-derived proteins have been expressed in P. aeruginosa to successfully inhibit biofilm formation.
Summary
Background
Despite numerous guidelines recommending prophylactic antibiotics prior to percutaneous endoscopic gastrostomy, their use remains controversial.
Aim
To conduct a systematic ...literature review and performed meta‐analyses to determine the benefit of antibiotic prophylaxis for percutaneous endoscopic gastrostomy placement.
Methods
We performed a systematic literature review by searching healthcare databases and grey literature for randomized‐controlled trials of antibiotic prophylaxis against wound infection after percutaneous endoscopic gastrostomy. Relative risks were calculated for individual trials and data pooled using fixed‐effects model. Relative risk reduction, absolute risk reduction and number needed to treat were calculated and are reported with 95% confidence intervals.
Results
Ten randomized‐controlled trials met the inclusion criteria and 1059 cases were pooled. Overall findings indicated that antibiotic prophylaxis resulted in a relative risk reduction of 64% and an absolute risk reduction of 15%. Number needed to treat to prevent one wound infection was 8. Cephalosporin prophylaxis was associated with a relative risk reduction of 64%, absolute risk reduction of 10% and number needed to treat of 10, whereas penicillin‐based prophylaxis was associated with a relative risk reduction of 62%, absolute risk reduction of 13% and number needed to treat of 8.
Conclusions
Antibiotic prophylaxis prior to percutaneous endoscopic gastrostomy is effective in reducing the incidence of percutaneous endoscopic gastrostomy site wound infection. Based on sensitivity analyses, penicillin‐based prophylaxis should be the prophylaxis of choice.
In deep inelastic multinucleon transfer reactions of 48Ca + 248Cm we observed about 100 residual nuclei with proton numbers between Z=82 and Z=100. Among them, there are five new neutron-deficient ...isotopes: 216U, 219Np, 223Am, 229Am and 233Bk. As separator for the transfer products we used the velocity filter SHIP of GSI while the isotope identification was performed via the α decay chains of the nuclei. These first results reveal that multinucleon transfer reactions together with here applied fast and sensitive separation and detection techniques are promising for the synthesis of new isotopes in the region of heaviest nuclei.
Abstract Background and aims To investigate if frequency of outdoor recreational activity (ORA) predicts cardiovascular disease (CVD) mortality, independent of serum 25(OH)D concentration. Methods ...and results Baseline data on ORA and serum 25(OH)D, collected from 11,746 participants aged 30–90 years in the Third National Health and Nutrition Examination Survey during 1988–1994, were linked to the National Death Index for assessment of CVD deaths from baseline through December 2006. CVD mortality as a primary cause of death was assessed during a mean follow up of 12.9 (SD, 4.2) years. There were 1519 CVD deaths during follow up. A strong positive association was observed between frequency of ORA in the last month and serum 25(OH)D (p < 0.001). Compared to participants who did no ORA in the last month, the hazard ratio (HR) of CVD mortality was 0.72 (95% confidence interval 0.58–0.90) for those doing ORA 1–4 times, 0.64 (0.47–0.89) for 5–12 times, 0.70 (0.56–0.89) for 13–30 times and 0.63 (0.47–0.84) for ≥30 times (p-trend < 0.001), in a Cox proportional hazards regression model which included 25(OH)D and CVD risk factors. Serum 25(OH)D was inversely associated with CVD mortality (p-trend, 0.01) in this same model. Conclusions An inverse association between ORA and CVD mortality was observed independent of 25(OH)D. The underlying mechanism for this association may not involve 25(OH)D hence, further studies are warranted to confirm and investigate the underlying mechanism.
Display omitted
•A new versatile probability distribution function called “hyper-EMG” is presented.•Modeling of asymmetric MR-TOF mass spectra using the hyper-EMG is demonstrated.•Peak shape is ...precisely modeled over 5 orders of magnitude in abundance.•Hyper-EMG outperforms the common peak shape models in case of overlapping peaks.•Improved mass and abundance values are obtained for overlapping peaks in MR-TOF-MS.
A new probability distribution function (PDF) called hyper-Exponentially Modified Gaussian (hyper-EMG) is introduced for the analysis of high-resolution spectra from multiple-reflection time-of-flight mass spectrometers. The hyper-EMG consists of a central Gaussian distribution modified by multiple exponential tails with different strengths at one or both sides. The basic statistical properties of the new PDF are given and the analysis of mass spectra containing separated and overlapping peaks is presented. The main requirement is to accurately determine the positions and areas of the individual mass peaks. From the distances of positions the mass values can be determined, from the areas the population of different ground and isomeric states can be obtained. The hyper-EMG has been applied to high-resolution time and mass spectra characterized by mass resolving powers of 140,000 and 520,000 obtained with Cs+133 and K+39 ions, respectively. From the measured mass distribution of K+39 ions, an overlapping distribution of two peaks with an area ratio of 1:10 and a mass difference of 2.6ppm (parts-per-million) is generated and analyzed. The results reveal significant advantages of the new PDF for the evaluation of overlapping distributions for accurate mass and area determinations compared with commonly used PDFs which are more than one order of magnitude less accurate. It is obvious that the hyper-EMG can be favorably applied also to other fields.
Novel device to study double-alpha decay at the FRS Ion Catcher Varga, L.; Wilsenach, H.; Hall, O. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/2024, Letnik:
1063
Journal Article
Recenzirano
Odprti dostop
A novel system has been developed to detect simultaneous double-alpha emission from purified and weightless sources. The system includes the collection of 224Ra low-energy recoils in purified helium ...buffer gas from the decay of 228Th. The recoil products are thermalized and collected in a cryogenic buffer gas cell and extracted into an RF-ion guide for mass selection. The mass-separated ions are implanted at low kinetic energy into a thin carbon foil placed between two large-area double-sided silicon strip detectors to observe correlated alpha-particle emission. The apparatus is described in detail, including insights into its experimental performance.
The FRagment Separator FRS at GSI is a versatile spectrometer and separator for experiments with relativistic in-flight separated short-lived exotic beams. One branch of the FRS is connected to the ...target hall where the bio-medical cave (Cave M) is located. Recently a joint activity between the experimental groups of the FRS and the biophysics at the GSI and Department of physics at LMU was started to perform biomedical experiments relevant for hadron therapy with positron emitting carbon and oxygen beams. This paper presents the new ion-optical mode and commissioning results of the FRS-Cave M branch where positron emitting 15O-ions were provided to the medical cave for the first time. An overall conversion efficiency of 2.9±0.2×10−415O fragments per primary 16O ion accelerated in the synchrotron SIS18 was reached.
211Po ions in the ground and isomeric states were produced via 238U projectile fragmentation at 1000 MeV/u. The 211Po ions were spatially separated in flight from the primary beam and other reaction ...products by the fragment separator FRS. The ions were energy-bunched, slowed-down and thermalized in a gas-filled cryogenic stopping cell (CSC). They were then extracted from the CSC and injected into a high-resolution multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS). The excitation energy of the isomer and, for the first time, the isomeric-to-ground state ratio were determined from the measured mass spectrum. In the subsequent experimental step, the isomers were spatially separated from the ions in the ground state by an ion deflector and finally collected with a silicon detector for decay spectroscopy. This pioneering experimental result opens up unique perspectives for isomer-resolved studies. With this versatile experimental method new isomers with half-lives longer than a few milliseconds can be discovered and their decay properties can be measured with highest sensitivity and selectivity. These experiments can be extended to studies with isomeric beams in nuclear reactions.
PDF
