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Bio-protocol Dec 2023In situ cryo-electron tomography (cryo-ET) is the most current, state-of-the-art technique to study cell machinery in its hydrated near-native state. The method provides...
In situ cryo-electron tomography (cryo-ET) is the most current, state-of-the-art technique to study cell machinery in its hydrated near-native state. The method provides ultrastructural details at sub-nanometer resolution for many components within the cellular context. Making use of recent advances in sample preparation techniques and combining this method with correlative light and electron microscopy (CLEM) approaches have enabled targeted molecular visualization. Nevertheless, the implementation has also added to the complexity of the workflow and introduced new obstacles in the way of streamlining and achieving high throughput, sample yield, and sample quality. Here, we report a detailed protocol by combining multiple newly available technologies to establish an integrated, high-throughput, optimized, and streamlined cryo-CLEM workflow for improved sample yield. Key features • PRIMO micropatterning allows precise cell positioning and maximum number of cell targets amenable to thinning with cryo focused-ion-beam-scanning electron microscopy. • CERES ice shield ensures that the lamellae remain free of ice contamination during the batch milling process. • METEOR in-chamber fluorescence microscope facilitates the targeted cryo focused-ion-beam (cryo FIB) milling of these targets. • Combining the three technologies into one cryo-CLEM workflow maximizes sample yield, throughput, and efficiency. Graphical overview.
PubMed: 38156035
DOI: 10.21769/BioProtoc.4901 -
Magnetic Resonance in Medicine Aug 2023Optimization of transmit array performance is crucial in ultra-high-field MRI scanners such as 11.7T because of the increased RF losses and RF nonuniformity. This work...
PURPOSE
Optimization of transmit array performance is crucial in ultra-high-field MRI scanners such as 11.7T because of the increased RF losses and RF nonuniformity. This work presents a new workflow to investigate and minimize RF coil losses, and to choose the optimum coil configuration for imaging.
METHODS
An 8-channel transceiver loop-array was simulated to analyze its loss mechanism at 499.415 MHz. A folded-end RF shield was developed to limit radiation loss and improve the efficiency. The coil element length, and the shield diameter and length were further optimized using electromagnetic (EM) simulations. The generated EM fields were used to perform RF pulse design (RFPD) simulations under realistic constraints. The chosen coil design was constructed to demonstrate performance equivalence in bench and scanner measurements.
RESULTS
The use of conventional RF shields at 11.7T resulted in significantly high radiation losses of 18.4%. Folding the ends of the RF shield combined with optimizing the shield diameter and length increased the absorbed power in biological tissue and reduced the radiation loss to 2.4%. The peak of the optimal array was 42% more than the reference array. Phantom measurements validated the numerical simulations with a close match of within 4% of the predicted .
CONCLUSION
A workflow that combines EM and RFPD simulations to numerically optimize transmit arrays was developed. Results have been validated using phantom measurements. Our findings demonstrate the need for optimizing the RF shield in conjunction with array element design to achieve efficient excitation at 11.7T.
Topics: Head; Radio Waves; Magnetic Resonance Imaging; Brain; Phantoms, Imaging; Equipment Design; Neuroimaging
PubMed: 36999747
DOI: 10.1002/mrm.29654 -
Polymers Apr 2024Polymer nanocomposites have recently been introduced as lead-free shielding materials for use in medical and industrial applications. In this work, novel shielding...
Polymer nanocomposites have recently been introduced as lead-free shielding materials for use in medical and industrial applications. In this work, novel shielding materials were developed using low-density polyethylene (LDPE) mixed with four different filler materials. These four materials are cement, cement with iron oxide, cement with aluminum oxide, and cement with bismuth oxide. Different weight percentages were used including 5%, 15%, and 50% of the cement filler with LDPE. Furthermore, different weight percentages of different combinations of the filler materials were used including 2.5%, 7.5%, and 25% (i.e., cement and iron oxide, cement and aluminum oxide, cement and bismuth oxide) with LDPE. Bismuth oxide was a nanocomposite, and the remaining oxides were micro-composites. Characterization included structural properties, physical features, mechanical and thermal properties, and radiation shielding efficiency for the prepared composites. The results show that a clear improvement in the shielding efficiency was observed when the filler materials were added to the LDPE. The best result out of all these composites was obtained for the composites of bismuth oxide (25 wt.%) cement (25 wt.%) and LDPE (50 wt.%) which have the lowest measured mean free path (MFP) compared with pure LDPE. The comparison shows that the average MFP obtained from the experiments for all the eight energies used in this work was six times lower than the one for pure LDPE, reaching up to twelve times lower for 60 keV energy. The best result among all developed composites was observed for the ones with bismuth oxide at the highest weight percent 25%, which can block up to 78% of an X-ray.
PubMed: 38611278
DOI: 10.3390/polym16071020 -
Stroke Jun 2024
PubMed: 38864221
DOI: 10.1161/STROKEAHA.124.044227 -
RoFo : Fortschritte Auf Dem Gebiete Der... Jun 2024Archaeological objects are often recovered in blocks since highly porous materials and unstable and highly decayed objects cannot always be uncovered undamaged or...
AIM
Archaeological objects are often recovered in blocks since highly porous materials and unstable and highly decayed objects cannot always be uncovered undamaged or time and resources for classic uncovering are lacking. Therefore, clinical computed tomography (CT) combined with freely available software solutions should be tested as a simple and fast method for visualizing and analyzing archaeological finds as an alternative to time-consuming restoration.
MATERIALS AND METHODS
As an example, a block with a shield boss was selected from a block excavation and examined by means of CT. Using the freely available software 3D-Slicer (https://www.slicer.org/), the shield boss and handle were segmented in the surrounding soil with different tools. They were then digitally reconstructed and then restored using Meshmixer (Autodesk Inc., San Francisco, CA). A 3D print was generated based on the reconstructed model of the shield boss.
RESULTS
The individual steps of CT examination of the block recovery, segmentation, reconstruction, and 3D printing were successfully performed. Based on the restored fragments of the shield boss, it was possible to date the object and to determine the initial properties of the find non-destructively without classic restoration.
CONCLUSION
Radiological imaging combined with digital reconstruction and 3D printing makes it possible to determine decisive characteristics of the archaeological find before it is uncovered and restored, which is a time-consuming process. This opens up new opportunities for cooperation between radiology and archaeology for the evaluation and analysis of archaeological finds.
KEY POINTS
· The transfer of medical technology, digital image processing and 3D printing to archaeology has been demonstrated.. · The digital restoration and reconstruction of archaeological objects using CT images is possible.. · Medical imaging could make a significant contribution to the investigation and reconstruction of archaeological objects..
CITATION FORMAT
· Frohwerk E, Dürr A, Fiebich M et al. Radiology meets archaeology: digital restoration and 3D printing using CT data. Fortschr Röntgenstr 2024; 196: 607 - 611.
Topics: Printing, Three-Dimensional; Archaeology; Tomography, X-Ray Computed; Humans; Software; Imaging, Three-Dimensional
PubMed: 38081192
DOI: 10.1055/a-2206-5741 -
Nucleic Acids Research Mar 2024Spermatogonial stem cells functionality reside in the slow-cycling and heterogeneous undifferentiated spermatogonia cell population. This pool of cells supports...
Spermatogonial stem cells functionality reside in the slow-cycling and heterogeneous undifferentiated spermatogonia cell population. This pool of cells supports lifelong fertility in adult males by balancing self-renewal and differentiation to produce haploid gametes. However, the molecular mechanisms underpinning long-term stemness of undifferentiated spermatogonia during adulthood remain unclear. Here, we discover that an epigenetic regulator, Polycomb repressive complex 1 (PRC1), shields adult undifferentiated spermatogonia from differentiation, maintains slow cycling, and directs commitment to differentiation during steady-state spermatogenesis in adults. We show that PRC2-mediated H3K27me3 is an epigenetic hallmark of adult undifferentiated spermatogonia. Indeed, spermatogonial differentiation is accompanied by a global loss of H3K27me3. Disruption of PRC1 impairs global H3K27me3 deposition, leading to precocious spermatogonial differentiation. Therefore, PRC1 directs PRC2-H3K27me3 deposition to maintain the self-renewing state of undifferentiated spermatogonia. Importantly, in contrast to its role in other tissue stem cells, PRC1 negatively regulates the cell cycle to maintain slow cycling of undifferentiated spermatogonia. Our findings have implications for how epigenetic regulators can be tuned to regulate the stem cell potential, cell cycle and differentiation to ensure lifelong fertility in adult males.
Topics: Humans; Male; Cell Differentiation; Histones; Polycomb Repressive Complex 1; Spermatogenesis; Spermatogonia; Stem Cells; Animals; Mice; Female; Polycomb Repressive Complex 2
PubMed: 38142439
DOI: 10.1093/nar/gkad1203 -
Journal of Clinical Monitoring and... Dec 2023Pulse oximeter accuracy is important for the quality and safety of patient care. Methodological errors occurring during pulse oximeter accuracy studies can confound... (Review)
Review
PURPOSE
Pulse oximeter accuracy is important for the quality and safety of patient care. Methodological errors occurring during pulse oximeter accuracy studies can confound results. One potential source of error during pulse oximeter comparison studies is optical interference due to sensor-to-sensor crosstalk. Optical crosstalk can occur whenever pulse oximeter sensors are tested in close proximity of one another, as occurs during pulse oximeter comparison studies.
METHODS
This publication represents the first comprehensive review of sensor-to-sensor crosstalk and other forms of optical interference during pulse oximeter comparison studies. A review of the published literature was undertaken to elucidate the mechanism of optical crosstalk, along with other forms of optical interference, and a solution (shielding) is offered.
RESULTS
When pulse oximeter sensors are placed close to each other, as occurs during comparison studies, the red and near-infrared light used can also enter an adjacent sensor and lead to error. Pulse oximeter manufacturers have designed systems to reject some forms of optical interference, such as ambient light. However, light emanating from adjacent sensors during comparison studies can cause artifact, and this can be exacerbated by sensor malposition. Proper sensor placement and use of optical shielding are the best solutions to prevent crosstalk.
CONCLUSIONS
Crosstalk and other forms of optical interference can corrupt pulse oximeter readings. Proper sensor placement and use of optical shielding of sensors are crucial steps to help protect the integrity of the data. Studies to further characterize crosstalk during pulse oximeter comparison studies are needed.
Topics: Humans; Oximetry; Oxygen; Infrared Rays
PubMed: 37610524
DOI: 10.1007/s10877-023-01060-y -
Journal of Healthcare Engineering 2023Wearing a mask greatly reduced the possibility of infection during the COVID-19 pandemic. However, major inconveniences occur regarding patients with upper limb...
Wearing a mask greatly reduced the possibility of infection during the COVID-19 pandemic. However, major inconveniences occur regarding patients with upper limb amputations, as they cannot independently wear masks. As a result, bacterial contamination is caused by medical staff touching the quilt when helping. Furthermore, this effect can occur with ordinary people due to accidental touch. This research aims to design an automatic and portable face shield assistive device based on surface electromyography (sEMG) signals. A concise face shield-wearing mechanism was built through 3D printing. A novel decision-making control method regarding a feature extraction model of 16 signal features and a Softmax classification neural network model were developed and tested on an STM32 microcontroller unit (MCU). The optimized electrode was fabricated using a carbon nanotube (CNT)/polydimethylsiloxane (PDMS). The design was further integrated and tested, showing a promising future for further implementation.
Topics: Humans; COVID-19; Pandemics; Electromyography; Neural Networks, Computer; Amputation, Surgical
PubMed: 37457493
DOI: 10.1155/2023/8231073 -
BioRxiv : the Preprint Server For... Oct 2023Auditory sensation is based in nanoscale vibration of the sensory tissue of the cochlea, the organ of Corti complex (OCC). Motion within the OCC is now observable due to...
Auditory sensation is based in nanoscale vibration of the sensory tissue of the cochlea, the organ of Corti complex (OCC). Motion within the OCC is now observable due to optical coherence tomography. In the cochlear base, in response to sound stimulation, the region that includes the electro-motile outer hair cells (OHC) was observed to move with larger amplitude than the basilar membrane (BM) and surrounding regions. The intense motion is based in active cell mechanics, and the region was termed the "hotspot" (Cooper et al., 2018, Nature comm). In addition to this quantitative distinction, the hotspot moved qualitatively differently than the BM, in that its motion scaled nonlinearly with stimulus level at all frequencies, evincing sub-BF activity. Sub-BF activity enhances non-BF motion; thus the frequency tuning of the hotspot was reduced relative to the BM. Regions that did not exhibit sub-BF activity are here defined as the OCC "frame". By this definition the frame includes the BM, the medial and lateral OCC, and most significantly, the reticular lamina (RL). The frame concept groups the majority OCC as a structure that is largely shielded from sub-BF activity. This shielding, and how it is achieved, are key to the active frequency tuning of the cochlea. The observation that the RL does not move actively sub-BF indicates that hair cell stereocilia are not exposed to sub-BF activity. A complex difference analysis reveals the motion of the hotspot relative to the frame.
PubMed: 37873430
DOI: 10.1101/2023.06.29.547111 -
Plastic and Reconstructive Surgery.... Jan 2024We aimed to investigate the effect of compression dressing on edema, ecchymosis, pain, and ocular surface irritation after ptosis surgery.
BACKGROUND
We aimed to investigate the effect of compression dressing on edema, ecchymosis, pain, and ocular surface irritation after ptosis surgery.
METHODS
After ptosis correction [anterior levator reinsertion (and resection) (ALR), if necessary additional blepharoplasty], the eye was randomized for compression dressing or transparent eye shield. Edema and ecchymosis were scored on a four-point rating scale by a blinded observer 1 day (D1), 1 week (D7), and 8 weeks (D56) after surgery; the same was done for scar formation regarding redness and bulging at D7 and D56. Aesthetic outcome was ranked by patient and blinded observer using the Global Aesthetic Improvement Score at D1, D7, and D56. Postoperative pain was scored using a visual analogue scale (0 to 10) at D1. Impairment after surgery by dressing or eye shield was evaluated at D1.
RESULTS
Ecchymosis, edema, scar formation, and aesthetic outcome ranked by the patient and blinded observer did not differ between the groups with compression dressing and eye shield at any day of follow-up ( > 0.05). Postoperative pain and impairment were the same in both groups ( > 0.05). One case of corneal erosion occurred in the group with compression dressing at D1 ( = 0.342). At D7, corneal staining was increased in the group without compression dressing ( = 0.930).
CONCLUSIONS
Compression dressing after ALR does not reduce ecchymosis, edema, or postoperative pain and has no effect on early scar formation or aesthetic results. To prevent corneal erosion caused by the dressing, it can be omitted after ALR without inferiority for the early postoperative results.
PubMed: 38264444
DOI: 10.1097/GOX.0000000000005548