Systemic reactivation of herpesviruses may occur in intensive care unit (ICU) patients and is associated with morbidity and mortality. Data on severe Coronavirus disease-19 (COVID-19) and concomitant ...reactivation of herpesviruses are lacking.
We selected patients admitted to ICU for confirmed COVID-19 who underwent systematic testing for Epstein-Barr virus (EBV), cytomegalovirus (CMV) and human-herpes virus-6 (HHV-6) DNAemia while in the ICU. We retrospectively analysed frequency, timing, duration and co-occurrence of viral DNAemia.
Thirty-four patients were included. Viremia with EBV, CMV, and HHV-6 was detected in 28 (82%), 5 (15%), and 7 (22%) patients, respectively. EBV reactivation occurred early after ICU admission and was associated with longer ICU length-of-stay.
While in the ICU, critically ill patients with COVID-19 are prone to develop reactivations due to various types of herpesviruses.
Hyperpolarized (hp) (129)Xe and hp (83)Kr for magnetic resonance imaging (MRI) are typically obtained through spin-exchange optical pumping (SEOP) in gas mixtures with dilute concentrations of the ...respective noble gas. The usage of dilute noble gases mixtures requires cryogenic gas separation after SEOP, a step that makes clinical and preclinical applications of hp (129)Xe MRI cumbersome. For hp (83)Kr MRI, cryogenic concentration is not practical due to depolarization that is caused by quadrupolar relaxation in the condensed phase. In this work, the concept of stopped flow SEOP with concentrated noble gas mixtures at low pressures was explored using a laser with 23.3 W of output power and 0.25 nm linewidth. For (129)Xe SEOP without cryogenic separation, the highest obtained MR signal intensity from the hp xenon-nitrogen gas mixture was equivalent to that arising from 15.5±1.9% spin polarized (129)Xe in pure xenon gas. The production rate of the hp gas mixture, measured at 298 K, was 1.8 cm(3)/min. For hp (83)Kr, the equivalent of 4.4±0.5% spin polarization in pure krypton at a production rate of 2 cm(3)/min was produced. The general dependency of spin polarization upon gas pressure obtained in stopped flow SEOP is reported for various noble gas concentrations. Aspects of SEOP specific to the two noble gas isotopes are discussed and compared with current theoretical opinions. A non-linear pressure broadening of the Rb D(1) transition was observed and taken into account for the qualitative description of the SEOP process.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Due to low fluorine background signal in vivo, 19F is a good marker to study the fate of exogenous molecules by magnetic resonance imaging (MRI) using equilibrium nuclear spin polarization schemes. ...Since 19F MRI applications require high sensitivity, it can be important to assess experimental feasibility during the design stage already by estimating the minimum detectable fluorine concentration. Here we propose a simple method for the calibration of MRI hardware, providing sensitivity estimates for a given scanner and coil configuration. An experimental "calibration factor" to account for variations in coil configuration and hardware set-up is specified. Once it has been determined in a calibration experiment, the sensitivity of an experiment or, alternatively, the minimum number of required spins or the minimum marker concentration can be estimated without the need for a pilot experiment. The definition of this calibration factor is derived based on standard equations for the sensitivity in magnetic resonance, yet the method is not restricted by the limited validity of these equations, since additional instrument-dependent factors are implicitly included during calibration. The method is demonstrated using MR spectroscopy and imaging experiments with different 19F samples, both paramagnetically and susceptibility broadened, to approximate a range of realistic environments.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Isolation of patients with multidrug resistant (MDR) bacteria is recommended to reduce cross-transmission of these bacteria. However, isolation of critically ill patients has several negative side ...effects. Therefore, we hypothesized that a targeted isolation strategy, based on the presence of at least one risk factor for MDR bacteria, would be not inferior to a systematic isolation strategy at intensive-care unit (ICU) admission.
This prospective before–after study was conducted in a mixed ICU, during two 12-month periods, separated by a 1-month ‘wash-out’ period. During the before period, isolation was systematically performed in all patients at admission. During the after period, isolation was only performed in patients with at least one risk factor for MDR bacteria at admission. During the two periods, routine screening for MDR bacteria was performed at ICU admission, and isolation prescription was modified after receipt of screening result. Primary outcome was the percentage of patients with ICU-acquired infection (ICUAI) related to MDR bacteria, measured from ICU admission until ICU discharge or day 28, whatever happens first.
A total of 1221 patients were included. No significant difference was found in ICUAI related to MDR bacteria (85 of 585 (14.5%) vs. 84 of 636 (13.2%) patients, risk difference, −1.3%, 95% confidence interval −5.2 to 2.6%) between the two periods, confirming the non-inferiority hypothesis.
Our results suggest that targeted isolation of patients at ICU admission is not inferior to systematic isolation, regarding the percentage of patients with ICUAI related to MDR bacteria. Further randomized controlled multicentre studies are needed to confirm our results.
Hyperpolarized (hp) 83Kr is a promising MRI contrast agent for the diagnosis of pulmonary diseases affecting the surface of the respiratory zone. However, the distinct physical properties of 83Kr ...that enable unique MRI contrast also complicate the production of hp 83Kr. This work presents a previously unexplored approach in the generation of hp 83Kr that can likewise be used for the production of hp 129Xe. Molecular nitrogen, typically used as buffer gas in spin-exchange optical pumping (SEOP), was replaced by molecular hydrogen without penalty for the achievable hyperpolarization. In this particular study, the highest obtained nuclear spin polarizations were P = 29% for 83Kr and P = 63% for 129Xe. The results were reproduced over many SEOP cycles despite the laser-induced on-resonance formation of rubidium hydride (RbH). Following SEOP, the H₂ was reactively removed via catalytic combustion without measurable losses in hyperpolarized spin state of either 83Kr or 129Xe. Highly spin-polarized 83Kr can now be purified for the first time, to our knowledge, to provide high signal intensity for the advancement of in vivo hp 83Kr MRI. More generally, a chemical reaction appears as a viable alternative to the cryogenic separation process, the primary purification method of hp 129Xe for the past 2 1/2 decades. The inherent simplicity of the combustion process will facilitate hp 129Xe production and should allow for on-demand continuous flow of purified and highly spin-polarized 129Xe.
Ex vivo rodent lung models are explored for physiological measurements of respiratory function with hyperpolarized (hp) (129)Xe MRI. It is shown that excised lung models allow for simplification of ...the technical challenges involved and provide valuable physiological insights that are not feasible using in vivo MRI protocols. A custom designed breathing apparatus enables MR images of gas distribution on increasing ventilation volumes of actively inhaled hp (129)Xe. Straightforward hp (129)Xe MRI protocols provide residual lung volume (RV) data and permit for spatially resolved tracking of small hp (129)Xe probe volumes during the inhalation cycle. Hp (129)Xe MRI of lung function in the excised organ demonstrates the persistence of post mortem airway responsiveness to intravenous methacholine challenges. The presented methodology enables physiology of lung function in health and disease without additional regulatory approval requirements and reduces the technical and logistical challenges with hp gas MRI experiments. The post mortem lung functional data can augment histological measurements and should be of interest for drug development studies.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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•Production of hyperpolarized (hp) 129Xe and hp 83Kr without cryogenic processing.•Single step extraction, transfer, and compression of hp gas after optical pumping.•Methodology is ...applied to obtain hp 129Xe and hp 83Kr MR images of excised rat lungs.•Precise mixing of hp gases with oxygen after extraction and before compression.•Oxygen dependent T1 relaxation in bulk gas phase and in excised rat lungs.
As an alternative to cryogenic gas handling, hyperpolarized (hp) gas mixtures were extracted directly from the spin exchange optical pumping (SEOP) process through expansion followed by compression to ambient pressure for biomedical MRI applications. The omission of cryogenic gas separation generally requires the usage of high xenon or krypton concentrations at low SEOP gas pressures to generate hp 129Xe or hp 83Kr with sufficient MR signal intensity for imaging applications. Two different extraction schemes for the hp gasses were explored with focus on the preservation of the nuclear spin polarization. It was found that an extraction scheme based on an inflatable, pressure controlled balloon is sufficient for hp 129Xe handling, while 83Kr can efficiently be extracted through a single cycle piston pump. The extraction methods were tested for ex vivo MRI applications with excised rat lungs. Precise mixing of the hp gases with oxygen, which may be of interest for potential in vivo applications, was accomplished during the extraction process using a piston pump. The 83Kr bulk gas phase T1 relaxation in the mixtures containing more than approximately 1% O2 was found to be slower than that of 129Xe in corresponding mixtures. The experimental setup also facilitated 129Xe T1 relaxation measurements as a function of O2 concentration within excised lungs.
Around 70% of the drinking water produced by De Watergroep (a Belgian public water company) is extracted from 83 groundwater pumping sites. To control the risks that endanger the drinking water ...supply and for the groundwater extracted to be as pure as possible, a risk-based approach for the protection of the catchment areas is developed, as part of the water safety plans. The approach consists of three steps: first, the compilation of a site-specific source file, second, the performance of a risk analysis for every catchment area, and third, the development of a monitoring strategy and action plans. The general goals are to lower the level of purification and to enhance the sustainability of groundwater extraction. The listed benefits make it worthwhile to implement this approach, despite the uncertainties.
AlN films, grown by nitrogen or argon ion beam-assisted pulsed laser deposition, exhibit very high stresses at a certain ion energy. These stresses are mainly caused by ion beam-induced defects. The ...magnitude of stress is found to depend not only on the ion energy, but also on the deposition temperature and the ion incidence angle. To explain the relation of the observed film stresses and the appropriate deposition parameters, a simple model was developed. The model takes into account the annealing of a certain fraction of the ion beam-induced point defects by thermal diffusion towards the film surface, which acts like a sink of the defect concentration. This model allows us to predict the ion energy where the point defect concentration in a film reaches a maximum in agreement with the experimental observation of the stress maximum.
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