Hasil untuk "Microscopy"

J. Seidel, L. Martin, Q. He et al.

P. Stoimenov, R. Klinger, G. Marchin et al.

R. Shukla, V. Bansal, Minakshi Chaudhary et al.

A. Zumbusch, G. Holtom, X. Xie et al.

Mingzhuo Chen, Weigang Ren, Xin Wu et al.

Monkeypox (Mpox), a zoonotic viral disease caused by the Monkeypox Virus (MPXV), has gained significant attention in recent years due to its increasing incidence and the grave threat it poses to global health. MPXV has spread at a rapid pace during the COVID-19 pandemic, causing 10,000+ confirmed cases and ~300 fatalities in 122 countries. This virus comprises two major clades, Clade I (Central African), which is evidently more virulent, and Clade II (West African), which has caused the recent outbreaks across the world and caused fewer deaths. Clinically, Mpox presents as a milder form with fever, lymphadenopathy, and vesiculopustular rash similar to smallpox. Diagnostic measures such as polymerase chain reaction (PCR) are the main diagnostic confirmatory tools. Advanced diagnostics involve electronic microscopy, serology, and immunohistochemistry. Alternative drugs like tecovirimat and brincidofovir have demonstrated potential for treating smallpox, but there is scanty evidence on their efficacy against MPXV. Most recent advancements in the study of vaccines have resulted in the creation and introduction of MVA-BN (JYNNEOS/Imvanex/Imvamune) and ACAM2000 vaccines, which conferred cross-protection against MPXV. MVA-BN is suggested to perform better than other types due to its enhanced safety and immunogenicity. Researchers are also developing DNA and protein subunit vaccines against Mpox to induce specific immune responses by presenting viral proteins. The discovery of novel vaccine candidates and antiviral treatments will be needed to prevent future outbreaks and reduce the global health burden of Mpox. This review focuses on the characterization of MPXV, summarizing current knowledge on its genomic structure, pathogenesis, replication, potential targets of anti-MPXV drugs, clinical features, and epidemiological patterns, along with recent advances in vaccine development.

Mingyang Li, Yu'an Li, H. P. Zhang et al.

Detecting Lévy flights of cells has been a challenging problem in experiments. The challenge lies in accessing data in spatiotemporal scales across orders of magnitude, which is necessary for reliably extracting a power-law scaling. Differential dynamic microscopy has been shown to be a powerful method that allows one to acquire statistics of cell motion across scales, which is a potentially versatile method for detecting Lévy walks in biological systems. In this article, we extend the differential dynamic microscopy method to self-propelled Lévy particles, whose run-time distribution has a algebraic tail. We validate our protocol using synthetic imaging data and show that a reliable detection of active Lévy particles requires accessing length scales of one order of magnitude larger than its persistence length. Applying the protocol to experimental data of E. coli and E. gracilis, we find that E. coli does not exhibit a signature of Lévy walks, while E. gracilis is better described as active Lévy particles.

Maristella Mastore, Elisa Broggio, Davide Banfi et al.

The increase in the world population and consequent rise in food demand have led to the extensive use of chemical pesticides, causing environmental and health concerns. In response, biological control methods, particularly those involving microbial agents, have emerged as sustainable alternatives within integrated pest management. This study highlights the potential of <i>Lysinibacillus fusiformis</i> as a biocontrol agent against the dipteran <i>Drosophila suzukii</i> (Matsumura) (Diptera: Drosophilidae), a pest responsible for damaging soft-skinned fruits. Experimental treatments using vegetative cells, spores, and secondary metabolites of <i>L. fusiformis</i> on <i>D. suzukii</i> larvae demonstrated significant larvicidal effects, accompanied by observable changes in gut morphology under microscopy. Moreover, preliminary immunological assays showed the interference of this bacterium with the host immune system. All the results indicate the suitability of <i>L. fusiformis</i> for its possible integration into sustainable agricultural practices, although additional research is required to understand its applicability in the field.

Mingshuan ZHU, Shien LI, Yixiong ZHANG

This study primarily focuses on the modification of concrete materials by incorporating graphene oxide (GO). The dispersion of GO in concrete was characterized through Fourier transform infrared spectrometer (FTIR) and scanning electron microscopy (SEM), and the ability of concrete specimens with varying GO content to endure mechanical and climate temperature challenges were investigated. Additionally, the energy conversion relationship during uniaxial compressive failure was analyzed. The experimental results show that when the GO content is 0.05 %, the top stress, top strain, ultimate strain, and elasticity modulus increase by 29.54 %, 23.41 %, 61.72 %, and 34.93 %, respectively, relative to the reference concrete. With a GO content of 0.03 %, the GO/recycled cement-based composite material exhibits the greatest strength improvement after 7 days of hydration. At a 0.02 % GO content, the GO/recycled cement-based composite material exhibits the most notable strength enhancement after 28 days of hydration. Relative to conventional concrete, GO substantially boosts the key characteristics of uniaxial compression tests, notably diminishing the rate at which elastic strain energy is discharged, increasing the dissipation energy, decreasing the brittleness, and augmenting the malleability and toughness of concrete. However, efficient dispersion and cost-effective production methods for GO have not yet been achieved, and there are no long-term engineering applications of GO-modified concrete. Further research into GO-modified concrete technologies is recommended to promote the practical application and production of GO-incorporated concrete composites.

J. Schulman, W. Stoeckenius, L. M. Prince

Matthias Roeper, Samuel Dominic Seddon, Zeeshan H. Amber et al.

Piezoresponse Force Microscopy (PFM) is one of the most widespread methods for investigating and visualizing ferroelectric domain structures down to the nanometer length scale. PFM makes use of the direct coupling of the piezoelectric response to the crystal lattice, and hence is most often applied to spatially map the 3-dimensional (3D) near-surface domain distribution of any polar or ferroic sample. Nonetheless, since most samples investigated by PFM are at least semiconducting or fully insulating, the electric ac field emerging from the conductive scanning force microscopy (SFM) tip, penetrates the sample, and hence may also couple to polar features that are deeply buried into the bulk of the sample under investigation. Thus, in the work presented here, we experimentally and theoretically explore the contrast and depth resolution capabilities of PFM, by analyzing the dependence of several key parameters. These key parameters include the depth of the buried feature, i.e. here a domain wall (DW), as well as PFM-relevant technical parameters such as the tip radius, the PFM drive voltage and frequency, and the signal-to-noise ratio. The theoretical predictions are experimentally verified using x-cut periodically-poled lithium niobate single crystals that are specially prepared into wedge-shaped samples, in order to allow the buried feature, here the DW, to be `positioned' at any depth into the bulk. This inspection essentially contributes to the fundamental understanding in PFM contrast analysis, and to the reconstruction of 3D domain structures down to a 1-$μ$m-penetration depth into the sample.

Yan Xin, Jun Lu, Ke Han

Delamination strength of REBCO is very important for its applications in large magnet projects. This work presented the transmission electron microscopy (TEM) investigation of the microstructures of the REBCO coated conductor to understand its delamination property. We found that the low delamination strength is associated with nano-voids formed at the IBAD MgO/Y2O3 interface.

Laura Fernández-García, Sooyeon Song, Joy Kirigo et al.

ABSTRACT Myriad bacterial anti-phage systems have been described and often the mechanism of programmed cell death is invoked for phage inhibition. However, there is little evidence of “suicide” under physiological conditions for these systems. Instead of death to stop phage propagation, we show here that persister cells, i.e., transiently-tolerant, dormant, antibiotic-insensitive cells, are formed and survive using the Escherichia coli C496_10 tripartite toxin/antitoxin system MqsR/MqsA/MqsC to inhibit T2 phage. Specifically, MqsR/MqsA/MqsC inhibited T2 phage by 105-fold and reduced T2 titers by 3,000-fold. During T2 phage attack, in the presence of MqsR/MqsA/MqsC, evidence of persistence includes the single-cell physiological change of reduced metabolism (via flow cytometry), increased spherical morphology (via transmission electron microscopy), and heterogeneous resuscitation. Critically, we found restriction-modification systems (primarily EcoK McrBC) work in concert with the toxin/antitoxin system to inactivate phage, likely while the cells are in the persister state. Hence, a phage attack invokes a stress response similar to antibiotics, starvation, and oxidation, which leads to persistence, and this dormant state likely allows restriction/modification systems to clear phage DNA. IMPORTANCE To date, there are no reports of phage infection-inducing persistence. Therefore, our results are important since we show for the first time that a phage-defense system, the MqsRAC toxin/antitoxin system, allows the host to survive infection by forming persister cells, rather than inducing cell suicide. Moreover, we demonstrate that the MqsRAC system works in concert with restriction/modification systems. These results imply that if phage therapy is to be successful, anti-persister compounds need to be administered along with phages.

A. Glauert, R. H. Glauert

Epoxy resins are suitable media for embedding for electron microscopy, as they set uniformly with virtually no shrinkage. A mixture of araldite epoxy resins has been developed which is soluble in ethanol, and which yields a block of the required hardness for thin sectioning. The critical modifications to the conventional mixtures are the choice of a plasticized resin in conjunction with an aliphatic anhydride as the hardener. The hardness of the final block can be varied by incorporating additional plasticizer, and the rate of setting can be controlled by the use of an amine accelerator. The properties of the araldite mixture can be varied quite widely by adjusting the proportions of the various constituents. The procedure for embedding biological specimens is similar to that employed with methacrylates, although longer soaking times are recommended to ensure the complete penetration of the more viscous epoxy resin. An improvement in the preservation of the fine structure of a variety of specimens has already been reported, and a typical electron microgram illustrates the present paper.

Runsheng Zhao, Kaiyu Fan, Weiqing Wan

Abstract Background To prevent thyroid storm and ensure surgical safety, it is imperative to regulate excessive thyroid hormone levels in patients with thyrotropin-secreting pituitary adenomas (TSHoma) prior to surgery. Somatostatin analogues (SSAs), such as octreotide, have showed efficacy in shrinking tumors, which may facilitate surgical resection. This retrospective study aimed to investigate the effect of shortterm preoperative octreotide treatment on the surgical outcome of TSHoma. Methods A total of 65 TSHoma patients from January 2010 to July 2019 were included in the study. Of these,41 patients received short-term preoperative octreotide (Sandostatin, intermittent subcutaneous injection) treatment and all patients subsequently underwent surgery. The following data were recorded: clinical manifestations, laboratory examinations, sellar region MRI, postoperative pathological and electron microscopy data, intraoperative situation, and follow-up (> 3 months) regarding hormone levels and tumor recurrence. Results There was no significant difference in the consistency and blood supply of the tumor between patients who received short-term preoperative octreotide treatment and those who did not. Additionally, preoperative short-term octreotide treatment (median of 10 days with a range of 6–18 days) did not significantly improve the rates of gross total resection (GTR) or biochemical remission. Moreover, electron microscopy revealed subcellular level impairments and cell apoptotic in the octreotide treated TSHoma specimens. Conclusion Preoperative octreotide treatment for the purpose of reducing excessive thyroid hormones may not enhance surgical outcomes, and the duration of octreotide treatment needs to be extended to fully benefit from the tumor-shrinking effects of SSAs.

Siham Abdulzehra, Davoud Jafari-Gharabaghlou, Nosratollah Zarghami

Background: Colorectal cancer (CRC) is a prevalent type of cancer, ranking third in incidence and fourth in cancer-related deaths globally. The increase in mortality rates related to colorectal cancer among younger patients is a cause for concern. Chemotherapy is the primary approach for palliative care in colon cancer, but the development of drug resistance limits its effectiveness. Apoptosis is a process of programmed cell death that plays a crucial role in regulating normal cell death and abnormal tissue degeneration in cancer. Genes such as caspase-3, caspase-9, p53, and survivin are involved in apoptosis induction. The field of nanotechnology has presented exciting opportunities for controlled drug delivery and addressing drug resistance in cancer. Niosomes are among the nanocarriers known for their impressive features, making them excellent candidates for drug delivery. In the current study, we investigate whether niosomal nanoparticles coated with FA have the ability to deliver oxaliplatin to drug-resistant cells effectively and potentially resistance reversion in colon cancer cells. Methods: The niosomal nanoparticles (NPs) were fabricated using the thin-film hydration method and characterized using DLS (Dynamic Light Scattering), FTIR (Fourier Transform Infrared Spectroscopy), SEM (Scanning Electron Microscopy), and AFM (Atomic Force Microscopy) systems. The drug release and drug encapsulation efficiency of the NPs were also determined. An MTT assay was performed on oxaliplatin-resistant cells to determine the IC50 values of the drug in its pure and nano-encapsulated forms. Gene expression of caspase-3, caspase-9, p53, and survivin was investigated using the qRT-PCR (quantitative Reverse Transcription Polymerase Chain Reaction) technique, and cell apoptosis or necrosis was quantified using flow cytometry. Results: Size, PDI, zeta potential, morphology, drug release, and encapsulation efficiency of fabricated niosomal NPs were acceptable. Oxaliplatin anti-cancer drug showed a higher impact on cancerous cells in nano-encapsulated form. The expression level of caspase-3, caspase-9, and p53 was increased which was in confirmation by flow cytometry results. Conclusion: Taken together, results of this study demonstrated potential effect of folate decorated oxaliplatin-loaded niosomal NPs to resistance-reversion of Oxaliplatin-resistance colon cancer cells.

Wanjun Liu, Si Chen, Wenqing Xie et al.

Abstract Background The mitochondrial gene MCCC2, a subunit of the heterodimer of 3-methylcrotonyl-CoA carboxylase, plays a pivotal role in catabolism of leucine and isovaleric acid. The molecular mechanisms and prognostic value still need to be explored in the context of specific cancers, including colorectal cancer (CRC). Methods In vitro and in vivo cell-based assays were performed to explore the role of MCCC2 in CRC cell proliferation, invasion, and migration. Mitochondrial morphology, membrane potential, intracellular reactive oxygen species (ROS), telomerase activity, and telomere length were examined and analyzed accordingly. Protein complex formation was detected by co-immunoprecipitation (CO-IP). Mitochondrial morphology was observed by transmission electron microscopy (TEM). The Cancer Genome Atlas (TCGA) CRC cohort analysis, qRT-PCR, and immunohistochemistry (IHC) were used to examine the MCCC2 expression level. The association between MCCC2 expression and various clinical characteristics was analyzed by chi-square tests. CRC patients’ overall survival (OS) was analyzed by Kaplan–Meier analysis. Results Ectopic overexpression of MCCC2 promoted cell proliferation, invasion, and migration, while MCCC2 knockdown (KD) or knockout (KO) inhibited cell proliferation, invasion, and migration. MCCC2 KD or KO resulted in reduced mitochondria numbers, but did not affect the gross ATP production in the cells. Mitochondrial fusion markers MFN1, MFN2, and OPA1 were all upregulated in MCCC2 KD or KO cells, which is in line with a phenomenon of more prominent mitochondrial fusion. Interestingly, telomere lengths of MCCC2 KD or KO cells were reduced more than control cells. Furthermore, we found that MCCC2 could specifically form a complex with telomere binding protein TRF2, and MCCC2 KD or KO did not affect the expression or activity of telomerase reverse transcriptase (TERT). Finally, MCCC2 expression was heightened in CRC, and patients with higher MCCC2 expression had favorable prognosis. Conclusions Together, we identified MCCC2 as a novel mediator between mitochondria and telomeres, and provided an additional biomarker for CRC stratification.

Simon Hettler, Raul Arenal

We explore the possibility of applying physical phase plates (PPs) in combination with aberration-corrected transmission electron microscopy. Phase-contrast transfer characteristics are calculated and compared for a thin-film based Zernike PP, a hole-free (HF) or Volta PP and an electrostatic Zach PP, considering their phase-shifting properties in combination with partial spatial coherence. The effect of slightly converging illumination conditions, often used in high-resolution applications, on imaging with PPs is discussed. Experiments with an unheated Zernike PP applied to various nanomaterial specimens and a qualitative analysis clearly demonstrates the general compatibility of PPs and aberration-corrected transmission electron microscopy. Calculations and experiments show the benefits of the approach, among which is a strong phase-contrast enhancement of a large range of spatial frequencies. This allows the simultaneous imaging of atomic-resolution structures and morphological features at the nanometer scale, with maximum phase contrast. The calculations can explain why the HFPP damps contrast transfer at higher spatial frequencies.

Mikołaj Rogalski, Maria Cywińska, Azeem Ahmad et al.

Quantitative phase microscopy (QPM) is often based on recording an object-reference interference pattern and its further phase demodulation. We propose Pseudo Hilbert Phase Microscopy (PHPM) where we combine pseudo thermal light source illumination and Hilbert spiral transform phase demodulation to achieve hybrid hardware-software-driven noise robustness and increase in resolution of single-shot coherent QPM. Those advantageous features stem from physically altering the laser spatial coherence and numerically restoring spectrally overlapped object spatial frequencies. Capabilities of the PHPM are demonstrated analyzing calibrated phase targets and live HeLa cells in comparison with laser illumination and phase demodulation via temporal phase shifting and Fourier transform techniques. Performed studies verified unique ability of the PHPM to couple single-shot imaging, noise minimization, and preservation of phase details.

Yazgan Tuna, Amer Al-Hiyasat, Jonathon Howard

Several techniques have been employed for the direct visualization of cytoskeletal filaments and their associated proteins. Total-internal-reflection-fluorescence (TIRF) microscopy has a high signal-to-background ratio, but it suffers from photobleaching and photodamage of the fluorescent proteins. Label-free techniques such as interference reflection microscopy (IRM) and interference scattering microscopy (iSCAT) circumvent the problem of photobleaching but cannot readily visualize single molecules. Here, we present a protocol for combining IRM with a commercial TIRF microscope for the simultaneous imaging of microtubule-associated proteins (MAPs) and dynamic microtubules in vitro. Our protocol allows for high-speed observation of MAPs interacting with dynamic microtubules. This improves on existing two-color TIRF setups by eliminating both the need for microtubule labeling and the need for several additional optical components, such as a second excitation laser. We image both channels on the same camera chip to avoid image-registration and frame-synchronization problems. We demonstrate our setup by visualizing single kinesin molecules walking on dynamic microtubules.

Elisa Ovidi, Valentina Laghezza Masci, Anna Rita Taddei et al.

In this study, essential oils (EOs) and hydrolates (Hys) from Italian hemp (<i>Cannabis sativa</i> L. Kompolti cv.) and hop (<i>Humulus Lupulus</i> L., Chinook cv.) supply chains were chemically characterized and tested to investigate their apoptotic potential for the first time. Headspace–Gas Chromatography–Mass Spectrometry (HS-GC-MS) techniques were performed to describe their volatile chemical profile, highlighting a composition rich in terpene derivatives such as monoterpenes and sesquiterpenes among which <i>β</i>-myrcene, limonene, <i>β</i>-caryophyllene and <i>α</i>-humulene were the main constituents of EOs; in contrast, linalool, <i>cis</i>-<i>p</i>-menth-2,8-dien-1-ol, terpinen-4-ol, <i>α</i>-terpineol, caryophyllene oxide, and <i>τ</i>-cadinol were found in the Hys. The cytotoxicity activity on human leukemia cells (HL60), human neuroblastoma cells (SH-SY5Y), human metastatic adenocarcinoma breast cells (MCF7), human adenocarcinoma breast cells (MDA), and normal breast epithelial cell (MCF10A) for the EOs and Hys was studied by MTT assay and cytofluorimetric analysis and scanning and transmission electron microscopy were performed to define ultrastructural changes and the mechanism of cells death for HL 60 cells. An induction of the apoptotic mechanism was evidenced for hemp and hop EOs after treatment with the corresponding EC₅₀ dose. In addition, TEM and SEM investigations revealed typical characteristics induced by the apoptotic pathway. Therefore, thanks to the integration of the applied methodologies with the used techniques, this work provides an overview on the metabolomic profile and the apoptotic potential of hemp and hop EOs and, for the first time, also of Hys. The findings of this preliminary study confirm that the EOs and Hys from <i>Cannabis</i> and <i>Humulus</i> species are sources of bioactive molecules with multiple biological effects yet to be explored.