We present a study of the application of the Jagiellonian positron emission tomograph (J-PET) for the registration of gamma quanta from decays of ortho-positronium (o-Ps). The J-PET is the first ...positron emission tomography scanner based on organic scintillators in contrast to all current PET scanners based on inorganic crystals. Monte Carlo simulations show that the J-PET as an axially symmetric and high acceptance scanner can be used as a multi-purpose detector well suited to pursue research including e.g. tests of discrete symmetries in decays of ortho-positronium in addition to the medical imaging. The gamma quanta originating from o-Ps decay interact in the plastic scintillators predominantly via the Compton effect, making the direct measurement of their energy impossible. Nevertheless, it is shown in this paper that the J-PET scanner will enable studies of the
o-Ps
→
3
γ
decays with angular and energy resolution equal to
σ
(
θ
)
≈
0
.
4
∘
and
σ
(
E
)
≈
4.1
keV
, respectively. An order of magnitude shorter decay time of signals from plastic scintillators with respect to the inorganic crystals results not only in better timing properties crucial for the reduction of physical and instrumental background, but also suppresses significantly the pile-ups, thus enabling compensation of the lower efficiency of the plastic scintillators by performing measurements with higher positron source activities.
Recent tests of a single module of the Jagiellonian Positron Emission Tomography system (J-PET) consisting of 30 cm long plastic scintillator strips have proven its applicability for the detection of ...annihilation quanta (0.511 MeV) with a coincidence resolving time (CRT) of 0.266 ns. The achieved resolution is almost by a factor of two better with respect to the current TOF-PET detectors and it can still be improved since, as it is shown in this article, the intrinsic limit of time resolution for the determination of time of the interaction of 0.511 MeV gamma quanta in plastic scintillators is much lower. As the major point of the article, a method allowing to record timestamps of several photons, at two ends of the scintillator strip, by means of matrix of silicon photomultipliers (SiPM) is introduced. As a result of simulations, conducted with the number of SiPM varying from 4 to 42, it is shown that the improvement of timing resolution saturates with the growing number of photomultipliers, and that the Formula: see text configuration at two ends allowing to read twenty timestamps, constitutes an optimal solution. The conducted simulations accounted for the emission time distribution, photon transport and absorption inside the scintillator, as well as quantum efficiency and transit time spread of photosensors, and were checked based on the experimental results. Application of the Formula: see text matrix of SiPM allows for achieving the coincidence resolving time in positron emission tomography of Formula: see text0.170 ns for 15 cm axial field-of-view (AFOV) and Formula: see text0.365 ns for 100 cm AFOV. The results open perspectives for construction of a cost-effective TOF-PET scanner with significantly better TOF resolution and larger AFOV with respect to the current TOF-PET modalities.
A novel method of hit time and hit position reconstruction in scintillator detectors is described. The method is based on comparison of detector signals with results stored in a library of ...synchronized model signals registered for a set of well-defined positions of scintillation points. The hit position is reconstructed as the one corresponding to the signal from the library which is most similar to the measurement signal. The time of the interaction is determined as a relative time between the measured signal and the most similar one in the library. A degree of similarity of measured and model signals is defined as the distance between points representing the measurement- and model-signal in the multi-dimensional measurement space. Novelty of the method lies also in the proposed way of synchronization of model signals enabling direct determination of the difference between time-of-flights (TOF) of annihilation quanta from the annihilation point to the detectors. The introduced method was validated using experimental data obtained by means of the double strip prototype of the J-PET detector and 22Na sodium isotope as a source of annihilation gamma quanta. The detector was built out from plastic scintillator strips with dimensions of 5mm×19mm×300mm, optically connected at both sides to photomultipliers, from which signals were sampled by means of the Serial Data Analyzer. Using the introduced method, the spatial and TOF resolution of about 1.3cm (σ) and 125ps (σ) were established, respectively.
An issue that is currently undergoing extensive study is the influence of human vaginal microbiota (VMB) on the health status of women and their neonates. Healthy women are mainly colonised with ...lactobacilli such as Lactobacillus crispatus, Lactobacillus jensenii, and Lactobacillus iners; however, other bacteria may be elements of the VMB, particularly in women with bacterial vaginosis. The implementation of culture-independent molecular methods in VMB characterisation, especially next-generation sequencing, have provided new information regarding bacterial diversity in the vagina, revealing a large number of novel, fastidious, and/or uncultivated bacterial species. These molecular studies have contributed new insights regarding the role of bacterial community composition. In this study, we discuss recent findings regarding the reproductive tract microbiome. Not only bacteria but also viruses and fungi constitute important components of the reproductive tract microbiome. We focus on aspects related to the impact of the maternal microbiome on foetal development, as well as the establishment of the neonatal microbiomes, including the placenta microbiome, and the haematogenous source of intrauterine infection. We also discuss whether the role of the vaginal microbiome is currently understood and appreciated.
Abstract Introduction Non-HLA antibodies specific for angiotensin II type 1 receptor (anti-AT1R) and endothelin-1 type A receptor (anti-ETAR) of vascular cells activate signaling pathways leading to ...cell proliferation and vascular injury. The aim of this study was to evaluate the impact of non-HLA antibodies on kidney allograft morphology and function in patients who underwent a kidney biopsy due to renal function impairment. Patients and Methods The study included 65 consecutive renal transplant patients who were evaluated for the presence of non-HLA and anti-HLA antibodies at the time of transplant biopsy. Results of pre-transplant CDC cross-match were negative. A kidney allograft biopsy was performed between 6 days and 13 years (42 ± 49 months) after transplantation, and the diagnosis was made on the basis of the Banff criteria. The level >9 U/L of anti-AT1R and anti-ETAR antibodies was considered high. Results A high level of non-HLA antibodies (anti-AT1R and/or anti-ETAR) was found in 7 (10.7%) of 65 patients at the time of biopsy. Graft loss in the non–HLA-positive patients was significantly higher (71% in non–HLA-positive cases after 7.8 ± 2.6 months vs 11% after 6 months in non-HLA–negative cases P = .00099). In these non–HLA-positive patients, the mean anti-AT1R level was 15.3 ± 9.4 U/L and the mean anti-ETAR level was 13.8 ± 8.6 U/L. In only 2 of these patients were anti-HLA antibodies additionally detected: anti-class I in 1 and anti-class II in both patients. The mean serum creatinine level was 2.34 ± 0.6 mg/dL at the time of biopsy. Results of an early biopsy revealed acute vascular rejection (Banff grade IIB). Chronic allograft injury was found (grading cg1-3, cv1-2, ci1-2, ct1-2) in the remaining 6 patients. C4d was present in 3 of 7 patients. Conclusions High levels of anti-AT1R and/or anti-ETAR antibodies were associated with morphological and functional allograft injury and graft loss in these study patients. Non-HLA antibodies can be helpful in assessing the risk of graft failure.
Introduction
The emergence of SARS-CoV-2 has enormously impacted healthcare systems around the world. Both patients and health care professionals have been subjected to a novel stressor which affects ...their everyday life and functioning. This issue is especially important to patients suffering from chronic diseases which had already been exposed to a psychological strain related to their primary diagnosis. As chronically ill patients are depending on the availability of a specific treatment i.e. in need of specific healthcare facilities and have more reasons to worry about their future and hence be more prone to suffer adverse psychological consequences than the general population.
Objectives
In this study we aimed to examine whether the psychological results of the pandemic affect chronically ill and whether the specific illness and other demographic factors account for any changes in perceived stress levels.
Methods
An online questionnaire has been distributed to 4 groups (n=369): 92 psoriasis patients, 73 dialysis patients, 100 patients after kidney transplantation and 104 multiple sclerosis patients. The study was conducted during the pandemic in Poland (June-July 2020). Perceived stress levels were measured by the Perceived Stress Scale (PSS).
Results
The preliminary results suggest elevated perceived stress levels among the studied groups. As the data are currently under statistical evaluation specific statistical conclusions are to be expected in November 2020.
Conclusions
As the described study was conducted during the SARS-CoV-2 pandemic in Poland, it stands to reason that the epidemiological situation affected the levels of perceived stress among chronically ill patients.
In this paper we estimate the time resolution of the J-PET scanner built from plastic scintillators. We incorporate the method of signal processing using the Tikhonov regularization framework and the ...kernel density estimation method. We obtain simple, closed-form analytical formulae for time resolution. The proposed method is validated using signals registered by means of the single detection unit of the J-PET tomograph built from a 30 cm long plastic scintillator strip. It is shown that the experimental and theoretical results obtained for the J-PET scanner equipped with vacuum tube photomultipliers are consistent.
After living kidney donation, a decrease of kidney function (described as estimated glomerular filtration rate eGFR) is observed in majority of donors. However, the loss is more significant in some ...patients without an explicable reason. The aim of this study was to identify quantitative parameters in computed tomography (CT) of the abdomen that would predict greater eGFR reduction after kidney removal.
One hundred and ten preoperative multiphase CT examinations of the abdomen of kidney donors were analyzed for the following renal parameters: cortex, parenchyma and pyramids volume, scarring thickness (low grade: <1 cm, high grade: >1 cm), cortical gaps, vascularisation, and cortex-to-aorta enhancement index (CAEI). The radiologic and biometric (eg, donor weight) parameters were correlated with eGFR (CKD-EPI formula) change between baseline and at discharge.
Donor weight was correlated with a loss of eGFR (P < .001). Kidney volumetric parameters including renal cortex and parenchyma volume, as well as renal artery cross-section area were associated with donor weight (r = 0.50 P < .001 and r = 0.39 P < .001). CAEI was correlated with a loss of eGFR (P = .003) and was related to the donor's sex in favor of men. Forty-one (37%) donors had an additional renal artery, which did not influence kidney function. No influence of cortical gaps or scarring on eGFR was observed.
CAEI may be a helpful tool in predicting greater short-term kidney function decrease after living kidney donation.
Male sex is the strongest risk factor of greater eGFR loss after kidney donation.
•Quantitative CT parameters are proposed for predonation evaluation of kidneys.•Cortex-to-aorta enhancement index positively correlated with eGFR decrease.•Renal quantitative CT parameters are correlated with donor's sex.
In microbiological terms, pharmaceutical products can be divided into two groups: sterile and non-sterile. Non-sterile drugs must satisfy the appropriate microbiological purity criteria which are ...included in pharmacopoeial monographs. Pharmacopoeial studies are prepared specifically with a view to ensuring that the medicinal product is therapeutically effective and safe for the patient. The analysis comprised the results of microbiological purity tests performed before the products are marketed. Total of 1285 samples of non-sterile drugs manufactured by different pharmaceutical plants in Polish were taken into study. The microbiological quality of drugs was assessed in accordance with the criteria included in the European Pharmacopoeia (EP). An analysis of test results demonstrated that the percentage of non-compliant samples was 1.87%. The groups of drugs, which the most often did not satisfy EPs’ requirements, were drugs containing raw materials of natural origin (5.7%). The samples of studied drugs that did not meet the criteria contained in EP, exceed the maximum allowable microbiological count limits and contained microbes whose presence is prohibited. The most common non-compliance was the excessive levels of the maximum acceptable fungal count (n=12) and the excessive the maximum acceptable aerobic microbial count (n=10).
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