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Proteomes Jan 2016The tapetum is a single layer of secretory cells which encloses the anther locule and sustains pollen development and maturation. Upon apoptosis, the remnants of the... (Review)
Review
The tapetum is a single layer of secretory cells which encloses the anther locule and sustains pollen development and maturation. Upon apoptosis, the remnants of the tapetal cells, consisting mostly of lipids and proteins, fill the pits of the sculpted exine to form the bulk of the pollen coat. This extracellular matrix forms an impermeable barrier that protects the male gametophyte from water loss and UV light. It also aids pollen adhesion and hydration and retains small signaling compounds involved in pollen-stigma communication. In this study, we have updated the list of the pollen coat's protein components and also discussed their functions in the context of sexual reproduction.
PubMed: 28248215
DOI: 10.3390/proteomes4010005 -
Micron (Oxford, England : 1993) May 2022Powder materials are used in all corners of materials science, from additive manufacturing to energy storage. Scanning electron microscopy (SEM) has developed to meet... (Review)
Review
Powder materials are used in all corners of materials science, from additive manufacturing to energy storage. Scanning electron microscopy (SEM) has developed to meet morphological, microstructural and bulk chemical powder characterization requirements. These include nanoscale elemental analysis and high-throughput morphological assays. However, spatially localized powder surface chemical information with similar resolution to secondary electron (SE) imaging is not currently available in the SEM. Recently, energy filtered (EF-) SEM has been used for surface chemical characterization by secondary electron hyperspectral imaging (SEHI). This review provides a background to existing powder characterization capabilities in the low voltage SEM provided by SE imaging, EDX analysis and BSE imaging and sets out how these capabilities could be extended for surface chemical analysis by applying SEHI to powders, with particular emphasis on air and beam sensitive powder surfaces. Information accessible by SEHI, its advantages and limitations, is set into the context of other chemical characterization methods that are commonly used for assessing powder surface chemistry such as by Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). The applicability of existing powder preparation methods for SEM to SEHI is also reviewed. An alternative preparation method is presented alongside first examples of SEHI characterization of powder surfaces. The commercial powder materials used as examples were carbon-fiber/polyamide composite powder feedstock (CarbonMide®) used in additive manufacturing and powders consisting of lithium nickel cobalt oxide (NMC). SEHI is shown to differentiate bonding present at carbonaceous material surfaces and extract information about the work function of metal oxide surfaces. The surface sensitivity of SEHI is indicated by comparison of pristine powders to those with surface material added in preparation. A minimum spatial localization of chemical information of 55 nm was achieved in differentiating regions of NMC surface chemistry by distinct SE spectra.
Topics: Electrons; Hyperspectral Imaging; Microscopy, Electron, Scanning; Photoelectron Spectroscopy; Powders
PubMed: 35325668
DOI: 10.1016/j.micron.2022.103234 -
Therapeutic Advances in Neurological... 2018So far, intravenous tissue-type plasminogen activator (tPA) and mechanical removal of arterial blood clot (thrombectomy) are the only available treatments for acute... (Review)
Review
So far, intravenous tissue-type plasminogen activator (tPA) and mechanical removal of arterial blood clot (thrombectomy) are the only available treatments for acute ischemic stroke. However, the short therapeutic window and the lack of specialized stroke unit care make the overall availability of both treatments limited. Additional agents to combine with tPA administration or thrombectomy to enhance efficacy and improve outcomes associated with stroke are needed. Stroke-induced inflammatory processes are a response to the tissue damage due to the absence of blood supply but have been proposed also as key contributors to all the stages of the ischemic stroke pathophysiology. Despite promising results in experimental studies, inflammation-modulating treatments have not yet been translated successfully into the clinical setting. This review will (a) describe the timing of the stroke immune pathophysiology; (b) detail the immune responses to stroke sift-through cell type; and
PubMed: 30083232
DOI: 10.1177/1756286418789854 -
Nihon Hoshasen Gijutsu Gakkai Zasshi 2021The purpose of this study was to evaluate the best phantom for calculating the becquerel calibration factor (BCF) and correction method to obtain the improvement of...
[Improvement of Standardized Uptake Value Accuracy in the Tc Body SPECT and SPECT/CT: Optimization of the Phantom for Calculating Becquerel Calibration Factor and Correction Method].
PURPOSE
The purpose of this study was to evaluate the best phantom for calculating the becquerel calibration factor (BCF) and correction method to obtain the improvement of standardized uptake value (SUV) accuracy in both single photon emission computed tomography (SPECT) and SPECT/CT.
METHOD
A SPECT/CT scanner was used in this study. BCFs were calculated using four phantoms with different cross sections including National Electrical Manufacturers Association International Electrotechnical Commission body phantom (NEMA IEC body phantom) filled with TcO, and five correction methods were used for reconstruction. SUVs were calculated by the NEMA IEC body phantom and pediatric phantom in house with these BCFs. We then measured SUV in the background region of the NEMA IEC body phantom, SUV and SUV of the 37-mm-diameter sphere.
RESULTS
In the SPECT scanner, SUV and SUV measured 1.04 and 4.02, respectively, in the case of BCF calculation and SUV measurement using NEMA IEC body phantoms without corrections. In the SPECT/CT scanner, SUV with CT attenuation correction (AC) was in agreement with the theoretical values using each phantom. SUV showed the same trend.
CONCLUSION
In the SPECT scanner, it is possible to obtain a highly accurate SUV by using a phantom that matches the size of the subject for BCF calculation and without correction. In the SPECT/CT scanner, highly accurate SUVs can be obtained by using CT-based attenuation correction, and these values do not depend on the size of the BCF calculation phantom.
Topics: Calibration; Child; Humans; Phantoms, Imaging; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed
PubMed: 34544916
DOI: 10.6009/jjrt.2021_JSRT_77.9.921 -
Cancer Biology & Therapy Dec 2022Screening strategies have demonstrated their potential for decreasing the incidence and mortality of cancers, particularly that of colorectal cancer (CRC). Another... (Review)
Review
Screening strategies have demonstrated their potential for decreasing the incidence and mortality of cancers, particularly that of colorectal cancer (CRC). Another strategy that has been developed to reduce CRC occurrence is the use of chemoprevention agents. Among them, aspirin is the most promising. Aspirin acts in colorectal tumourigenesis through several mechanisms, either directly in tumor cells or in their microenvironment, such as through its anti-inflammatory activity or its effect on the modulation of platelet function. Many retrospective studies, as well as follow-up of large cohorts from trials with primary cardiovascular end points, have shown that long-term treatment with daily low-dose aspirin decreases the incidence of adenomas and colorectal cancers. Therefore, aspirin is currently recommended by the United States Preventive Services Task Force (USPSTF) for primary prevention of CRC in all patients aged 50 to 59 with a 10-y risk of cardiovascular events greater than 10%. Furthermore, several studies have also reported that long-term aspirin treatment taking after CRC resection decreases recurrence risk and increases overall survival, especially in patients with -mutated tumors. This review summarizes current knowledge on the pathophysiological mechanisms of aspirin chemoprevention, discusses the primary clinical results on CRC prevention and highlights the potential biomarkers identified to predict aspirin efficacy.
Topics: Adenoma; Anti-Inflammatory Agents, Non-Steroidal; Aspirin; Chemoprevention; Colorectal Neoplasms; Humans; Retrospective Studies; Tumor Microenvironment
PubMed: 35905195
DOI: 10.1080/15384047.2022.2104561 -
Lancet (London, England) Sep 2016Polonium-210 ((210)Po) gained widespread notoriety after the poisoning and subsequent death of Mr Alexander Litvinenko in London, UK, in 2006. Exposure to (210)Po...
BACKGROUND
Polonium-210 ((210)Po) gained widespread notoriety after the poisoning and subsequent death of Mr Alexander Litvinenko in London, UK, in 2006. Exposure to (210)Po resulted initially in a clinical course that was indistinguishable from infection or exposure to chemical toxins, such as thallium.
METHODS
A 43-year-old man presented to his local hospital with acute abdominal pain, diarrhoea, and vomiting, and was admitted to the hospital because of dehydration and persistent gastrointestinal symptoms. He was initially diagnosed with gastroenteritis and treated with antibiotics. Clostridium difficile toxin was subsequently detected in his stools, which is when he first raised the possibility of being poisoned and revealed his background and former identity, having been admitted under a new identity with which he had been provided on being granted asylum in the UK. Within 6 days, the patient had developed thrombocytopenia and neutropenia, which was initially thought to be drug induced. By 2 weeks, in addition to bone marrow failure, he had evidence of alopecia and mucositis. Thallium poisoning was suspected and investigated but ultimately dismissed because blood levels of thallium, although raised, were lower than toxic concentrations. The patient continued to deteriorate and within 3 weeks had developed multiple organ failure requiring ventilation, haemofiltration, and cardiac support, associated with a drop in consciousness. On the 23rd day after he first became ill, he suffered a pulseless electrical activity cardiorespiratory arrest from which he could not be resuscitated and was pronounced dead.
FINDINGS
Urine analysis using gamma-ray spectroscopy on day 22 showed a characteristic 803 keV photon emission, raising the possibility of (210)Po poisoning. Results of confirmatory analysis that became available after the patient's death established the presence of (210)Po at concentrations about 10(9)-times higher than normal background levels. Post-mortem tissue analyses showed autolysis and retention of (210)Po at lethal doses in several organs. On the basis of the measured amounts and tissue distribution of (210)Po, it was estimated that the patient had ingested several 1000 million becquerels (a few GBq), probably as a soluble salt (eg, chloride), which delivered very high and fatal radiation doses over a period of a few days.
INTERPRETATION
Early symptoms of (210)Po poisoning are indistinguishable from those of a wide range of chemical toxins. Hence, the diagnosis can be delayed and even missed without a high degree of suspicion. Although body surface scanning with a standard Geiger counter was unable to detect the radiation emitted by (210)Po, an atypical clinical course prompted active consideration of poisoning with radioactive material, with the diagnosis ultimately being made with gamma-ray spectroscopy of a urine sample.
FUNDING
UK NHS, Public Health England, and the UK Department of Health.
Topics: Abdominal Pain; Adult; Alopecia; Consciousness Disorders; Delayed Diagnosis; Diagnosis, Differential; England; Fatal Outcome; Gastroenteritis; Heart Arrest; Humans; Male; Mucositis; Multiple Organ Failure; Neutropenia; Poisoning; Polonium; Respiratory Insufficiency; Thrombocytopenia
PubMed: 27461439
DOI: 10.1016/S0140-6736(16)00144-6 -
Scientific Reports Jun 2021This work explores the distribution of time intervals between signals from the photomultiplier tubes (PMTs) of a liquid scintillation counting (LSC) system when a...
This work explores the distribution of time intervals between signals from the photomultiplier tubes (PMTs) of a liquid scintillation counting (LSC) system when a scintillation burst caused by an ionizing particle is detected. This distribution is termed the cross-correlation distribution and it is shown that it contains information about the probability to detect a scintillation event. A theoretical model that describes the cross-correlation distribution is derived. The model can be used to estimate the mean number of detected photons in a LSC measurement, which allows the calculation of the detection efficiency. The theoretical findings are validated by Monte Carlo simulations and by experiments with low-energy beta-emitting and electron-capture radionuclides ([Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text]), with dedicated LSC systems and several commercial LSC cocktails. The results show that some of the parameters of the cross-correlation distribution such as the peak height or the kurtosis can be used as detection efficiency estimators or quenching indicators in LSC. Thus, although the time domain and the cross-correlation distribution have received little to no attention in the practice of LSC, they have the capacity to bring significant improvements in almost all LSC applications related to activity determination of low-energy beta-emitting and electron-capture radionuclides. The results also suggest concepts for the development of innovative LSC systems.
PubMed: 34127742
DOI: 10.1038/s41598-021-91873-1 -
HemaSphere Jun 2022The rapid evolution of genomic technologies over the last years has led to the development of different methods for the detection, measurement and analysis of cell-free...
The rapid evolution of genomic technologies over the last years has led to the development of different methods for the detection, measurement and analysis of cell-free DNA fragments (cfDNA) which are shed into the bloodstream by apoptotic cells and circulate at a low concentration in plasma. In cancer patients, the proportion of tumor-derived cfDNA is defined as circulating tumor DNA. This analysis, commonly known as liquid biopsy, allows to access tumor DNA through a simple blood sampling and therefore without the need of an invasive tissue biopsy. For this reason, this tool may have several clinical applications in terms of diagnosis, prognosis, and monitoring of minimal residual disease. However, there are still several critical issues that need to be resolved. In this review, we will discuss some of the controversies around this method and its potential clinical applications.
PubMed: 35747846
DOI: 10.1097/HS9.0000000000000727 -
Journal of Applied Clinical Medical... Jul 2022The purpose of this study was to evaluate the positioning uncertainties of two PET/CT-MR imaging setups, C1 and C2. Because the PET/CT data were acquired on the same...
The purpose of this study was to evaluate the positioning uncertainties of two PET/CT-MR imaging setups, C1 and C2. Because the PET/CT data were acquired on the same hybrid device with automatic image registration, experiments were conducted using CT-MRI data. In C1, a transfer table was used, which allowed the patient to move from one imager to another while maintaining the same position. In C2, the patient stood up and was positioned in the same radiotherapy treatment position on each imager. The two setups provided a set of PET/CT and MR images. The accuracy of the registration software was evaluated on the CT-MRI data of one patient using known translations and rotations of MRI data. The uncertainties on the two setups were estimated using a phantom and a cohort of 30 patients. The accuracy of the positioning uncertainties was evaluated using descriptive statistics and a t-test to determine whether the mean shift significantly deviated from zero (p < 0.05) for each setup. The maximum registration errors were less than 0.97 mm and 0.6° for CT-MRI registration. On the phantom, the mean total uncertainties were less than 2.74 mm and 1.68° for C1 and 1.53 mm and 0.33° for C2. For C1, the t-test showed that the displacements along the z-axis did not significantly deviate from zero (p = 0.093). For C2, significant deviations from zero were present for anterior-posterior and superior-inferior displacements. The mean total uncertainties were less than 4 mm and 0.42° for C1 and less than 1.39 mm and 0.27° for C2 in the patients. Furthermore, the t-test showed significant deviations from zero for C1 on the anterior-posterior and roll sides. For C2, there was a significant deviation from zero for the left-right displacements.This study shows that transfer tables require careful evaluation before use in radiotherapy.
Topics: Humans; Magnetic Resonance Imaging; Patient Positioning; Phantoms, Imaging; Positron Emission Tomography Computed Tomography; Radiotherapy Planning, Computer-Assisted; Tomography, X-Ray Computed
PubMed: 35481611
DOI: 10.1002/acm2.13617 -
Haematologica Sep 2016Classical Hodgkin lymphoma is one of the most common lymphomas and shares clinical and genetic features with primary mediastinal B-cell lymphoma. In this retrospective...
Classical Hodgkin lymphoma is one of the most common lymphomas and shares clinical and genetic features with primary mediastinal B-cell lymphoma. In this retrospective study, we analyzed the recurrent hotspot mutation of the exportin 1 (XPO1, p.E571K) gene, previously identified in primary mediastinal B-cell lymphoma, in biopsies and plasma circulating cell-free DNA from patients with classical Hodgkin lymphoma using a highly sensitive digital PCR technique. A total of 94 patients were included in the present study. This widely expressed XPO1 E571K mutation is present in one quarter of classical Hodgkin lymphoma patients (24.2%). Mutated and wild-type classical Hodgkin lymphomas were similar regarding the main clinical features. Patients with a detectable XPO1 mutation at the end of treatment displayed a tendency toward shorter progression-free survival, as compared to patients with undetectable mutation in plasma cell-free DNA (2-year progression-free survival: 57.1%, 95% confidence interval: 30.1-100% versus 2-year progression-free survival: 90.5%, 95% confidence interval: 78.8-100%, respectively, P=0.0601). To conclude, the detection of the XPO1 E571K mutation in biopsy and plasma cell-free DNA by digital PCR may be used as a novel biomarker in classical Hodgkin lymphoma for both diagnosis and minimal residual disease, and pinpoints a crucial role of XPO1 in classical Hodgkin lymphoma pathogenesis. The detection of somatic mutation in the plasma cell-free DNA of patients represents a major technological advance in the context of liquid biopsies and noninvasive management of classical Hodgkin lymphoma.
Topics: Adult; Amino Acid Substitution; Biomarkers, Tumor; Cell Line, Tumor; Codon; Combined Modality Therapy; DNA, Neoplasm; Female; High-Throughput Nucleotide Sequencing; Hodgkin Disease; Humans; Karyopherins; Male; Middle Aged; Mutation; Neoplasm Staging; Neoplasms; Positron Emission Tomography Computed Tomography; Prognosis; Receptors, Cytoplasmic and Nuclear; Recurrence; Retrospective Studies; Survival Analysis; Treatment Outcome; Tumor Burden; Young Adult; Exportin 1 Protein
PubMed: 27479820
DOI: 10.3324/haematol.2016.145102