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Clinical Toxicology (Philadelphia, Pa.) Nov 2023Osmium tetroxide is a strong oxidizing agent. After dermal exposure to osmium tetroxide, skin discoloration and red papules can occur. We describe a patient with skin...
INTRODUCTION
Osmium tetroxide is a strong oxidizing agent. After dermal exposure to osmium tetroxide, skin discoloration and red papules can occur. We describe a patient with skin discoloration due to osmium tetroxide.
CASE SUMMARY
A 25-year-old postgraduate student unintentionally exposed his hand to osmium tetroxide while working in a laboratory setting. After immediate washing, he sought medical care due to left middle finger discoloration. He reported no discomfort in the affected area. Thorough water rinsing was continued, and corticosteroid ointment was applied.
IMAGES
Our patient developed dark brown pigmentation on the ventral side of the left middle finger. The pigmentation disappeared one week later.
CONCLUSION
Osmium tetroxide may induce dark brown skin discoloration.
Topics: Adult; Humans; Male; Osmium Tetroxide; Skin Diseases
PubMed: 37987740
DOI: 10.1080/15563650.2023.2281253 -
Frontiers in Neurology 2024Despite its location near infection-prone areas, the human inner ear demonstrates remarkable resilience. This suggests that there are inherent instruments deterring the...
BACKGROUND
Despite its location near infection-prone areas, the human inner ear demonstrates remarkable resilience. This suggests that there are inherent instruments deterring the invasion and spread of pathogens into the inner ear. Here, we combined high-resolution light microscopy, super-resolution immunohistochemistry (SR-SIM) and synchrotron phase contrast imaging (SR-PCI) to identify the protection and barrier systems in the various parts of the human inner ear, focusing on the lateral wall, spiral ganglion, and endolymphatic sac.
MATERIALS AND METHODS
Light microscopy was conducted on mid-modiolar, semi-thin sections, after direct glutaraldehyde/osmium tetroxide fixation. The tonotopic locations were estimated using SR-PCI and 3D reconstruction in cadaveric specimens. The sections were analyzed for leucocyte and macrophage activity, and the results were correlated with immunohistochemistry using confocal microscopy and SR-SIM.
RESULTS
Light microscopy revealed unprecedented preservation of cell anatomy and several macrophage-like cells that were localized in the cochlea. Immunohistochemistry demonstrated IBA1 cells frequently co-expressing MHC II in the spiral ganglion, nerve fibers, lateral wall, spiral limbus, and tympanic covering layer at all cochlear turns as well as in the endolymphatic sac. RNAscope assays revealed extensive expression of fractalkine gene transcripts in type I spiral ganglion cells. CD4 and CD8 cells occasionally surrounded blood vessels in the modiolus and lateral wall. TMEM119 and P2Y12 were not expressed, indicating that the cells labeled with IBA1 were not microglia. The round window niche, compact basilar membrane, and secondary spiral lamina may form protective shields in the cochlear base.
DISCUSSION
The results suggest that the human cochlea is surveilled by dwelling and circulating immune cells. Resident and blood-borne macrophages may initiate protective immune responses via chemokine signaling in the lateral wall, spiral lamina, and spiral ganglion at different frequency locations. Synchrotron imaging revealed intriguing protective barriers in the base of the cochlea. The role of the endolymphatic sac in human inner ear innate and adaptive immunity is discussed.
PubMed: 38817543
DOI: 10.3389/fneur.2024.1355785 -
BioRxiv : the Preprint Server For... Sep 2023Mapping the complete synaptic connectivity of a mammalian brain would be transformative, revealing the pathways underlying perception, behavior, and memory. Serial...
Mapping the complete synaptic connectivity of a mammalian brain would be transformative, revealing the pathways underlying perception, behavior, and memory. Serial section electron microscopy, via membrane staining using osmium tetroxide, is ideal for visualizing cells and synaptic connections but, in whole brain samples, faces significant challenges related to chemical treatment and volume changes. These issues can adversely affect both the ultrastructural quality and macroscopic tissue integrity. By leveraging time-lapse X-ray imaging and brain proxies, we have developed a 12-step protocol, ODeCO, that effectively infiltrates osmium throughout an entire mouse brain while preserving ultrastructure without any cracks or fragmentation, a necessary prerequisite for constructing the first comprehensive mouse brain connectome.
PubMed: 37808722
DOI: 10.1101/2023.09.26.558265 -
Microscopy (Oxford, England) Oct 2023Correlative fluorescent and electron microscopic images of the same section of epoxy (or other polymer)-embedded samples, hereafter referred to as 'in-resin CLEM', have...
Correlative fluorescent and electron microscopic images of the same section of epoxy (or other polymer)-embedded samples, hereafter referred to as 'in-resin CLEM', have been developed to improve the positional accuracy and Z-axis resolution limitations of conventional correlative light and electron microscopy (CLEM). High-pressure freezing and quick-freezing substitution result in in-resin CLEM of acrylic-based resin-embedded cells expressing green fluorescent protein, yellow fluorescent protein, mVenus and mCherry, which are sensitive to osmium tetroxide. The identification of osmium-resistant fluorescent proteins leads to the development of in-resin CLEM of Epon-embedded cells. Using subtraction-based fluorescence microscopy with a photoconvertible fluorescent protein, mEosEM-E, its green fluorescence can be observed in thin sections of Epon-embedded cells, and two-color in-resin CLEM using mEosEM-E and mScarlet-H can be performed. Green fluorescent proteins, CoGFP variant 0 and mWasabi, and far-red fluorescent proteins, mCherry2 and mKate2, are available for in-resin CLEM of Epon-embedded cells using the standard procedure for Epon-embedding with additional incubation. Proximity labeling is applied to in-resin CLEM to overcome the limitations of fluorescent proteins in epoxy resin. These approaches will contribute significantly to the future of CLEM analysis.
Topics: Humans; Epoxy Resins; Microscopy, Electron; Microscopy, Fluorescence; Green Fluorescent Proteins; HeLa Cells
PubMed: 37217182
DOI: 10.1093/jmicro/dfad028 -
Endocrine Jan 2024Accumulation of bone marrow adipose tissue (BMAT) is always seen in osteoporosis induced by estrogen deficiency. Herein, we aimed to investigate the mechanisms and...
BACKGROUND
Accumulation of bone marrow adipose tissue (BMAT) is always seen in osteoporosis induced by estrogen deficiency. Herein, we aimed to investigate the mechanisms and consequences of this phenomenon by establishing a mouse model of osteoporosis caused by ovariectomy (OVX)-mimicked estrogen deficiency.
METHODS
Micro-CT, osmium tetroxide staining, and histological analyses were performed to examine the changes in bone microstructure, BMAT and white adipose tissue (WAT) in OVX mice compared to sham mice. The osteogenesis and adipogenesis of primary bone marrow stromal cells (BMSCs) isolated from sham and OVX mice were compared in vitro. The molecular phenotypes of BMAT and WAT were determined and compared by quantitative PCR (qPCR). Bone marrow adipocyte-conditioned medium (BMA CM) was prepared from sham or OVX mice for coculture assays, and BMSCs or bone marrow monocytes/macrophages (BMMs) were isolated and subjected to osteoblast and osteoclast differentiation, respectively. Cell staining and qPCR were used to assess the effects of BMAT on bone metabolism.
RESULTS
OVX-induced estrogen deficiency induced reductions in both cortical and trabecular bone mass along with an expansion of BMAT volume. At the cellular level, loss of estrogen inhibited BMSC osteogenesis and promoted BMSC adipogenesis, whereas addition of estradiol exerted the opposite effects. In response to estrogen deficiency, despite the common proinflammatory molecular phenotype observed in both fat depots, BMAT, unlike WAT, unexpectedly exhibited an increase in adipocyte differentiation and lipolytic activity as well as the maintenance of insulin sensitivity. Importantly, BMAT, but not WAT, presented increased mRNA levels of both BMP receptor inhibitors (Grem1, Chrdl1) and Rankl following OVX. In addition, treatment with BMA CM, especially from OVX mice, suppressed the osteoblast differentiation of BMSCs while favoring the osteoclast differentiation of BMMs.
CONCLUSION
Our study illustrates that OVX-induced estrogen deficiency results in bone loss and BMAT expansion by triggering imbalance between the osteogenesis and adipogenesis of BMSCs. Furthermore, expanded BMAT, unlike typical WAT, may negatively regulate bone homeostasis through paracrine inhibition of osteoblast-mediated bone formation and promotion of osteoclast-mediated bone resorption.
Topics: Female; Mice; Animals; Humans; Bone Marrow; Adipose Tissue; Osteoporosis; Osteogenesis; Cell Differentiation; Estrogens; Ovariectomy; Eye Proteins; Nerve Tissue Proteins
PubMed: 37682419
DOI: 10.1007/s12020-023-03504-6 -
Microscopy (Oxford, England) Nov 2023Biological nanoparticles, such as bacterial outer membrane vesicles (OMVs), are routinely characterized through transmission electron microscopy (TEM). In this study, we...
Biological nanoparticles, such as bacterial outer membrane vesicles (OMVs), are routinely characterized through transmission electron microscopy (TEM). In this study, we report a novel method to prepare OMVs for TEM imaging. To preserve vesicular shape and structure, we developed a dual fixation protocol involving osmium tetroxide incubation prior to negative staining with uranyl acetate. Combining osmium tetroxide with uranyl acetate resulted in preservation of sub-50 nm vesicles and improved morphological stability, enhancing characterization of lipid-based nanoparticles by TEM.
Topics: Microscopy, Electron; Coloring Agents; Osmium Tetroxide; Bacterial Outer Membrane; Microscopy, Electron, Transmission; Staining and Labeling; Osmium
PubMed: 37148329
DOI: 10.1093/jmicro/dfad027 -
Journal of Visualized Experiments : JoVE Jan 2024Correlative light and electron microscopy (CLEM) is a comprehensive microscopy that combines the localization information provided by fluorescence microscopy (FM) and...
Correlative light and electron microscopy (CLEM) is a comprehensive microscopy that combines the localization information provided by fluorescence microscopy (FM) and the context of cellular ultrastructure acquired by electron microscopy (EM). CLEM is a trade-off between fluorescence and ultrastructure, and usually, ultrastructure compromises fluorescence. Compared with other hydrophilic embedding resins, such as glycidyl methacrylate, HM20, or K4M, Epon is superior in ultrastructure preservation and sectioning properties. Previously, we had demonstrated that mEosEM can survive osmium tetroxide fixation and Epon embedding. Using mEosEM, we achieved, for the first time, Epon post embedding CLEM, which maintains the fluorescence and the ultrastructure simultaneously. Here, we provide step-by-step details about the EM sample preparation, the FM imaging, the EM imaging, and the image alignment. We also improve the procedures for identifying the same cell imaged by FM imaging during the EM imaging and detail the registration between the FM and EM images. We believe one can easily achieve Epon post embedding correlative light and electron microscopy following this new protocol in traditional EM facilities.
Topics: Microscopy, Electron; Microscopy, Fluorescence
PubMed: 38284521
DOI: 10.3791/66141 -
Anatomical Record (Hoboken, N.J. : 2007) Aug 2023The guinea pig has been chosen as a research model for otologic or neuropathic studies due to the relative ease of the cochlea, cochlear nerve, and vestibular nerve...
The guinea pig has been chosen as a research model for otologic or neuropathic studies due to the relative ease of the cochlea, cochlear nerve, and vestibular nerve dissection. Little data have been reported on the normality of these nerves. The vestibular nerve is composed of the superior vestibular, inferior vestibular, and branch nerves. This study aimed to study the microscopic anatomy of the superior vestibular nerve (SVN) of guinea pigs using light microscopy and to search for normality patterns for use in experimental models in basic otologic research. We used eight male albino guinea pigs (Cavia porcellus, English strain), weighing between 400 and 500 g. After anesthetizing, the animals were perfused with a fixative solution of 2.5% glutaraldehyde. Dissection was performed by the access method to the temporal bone, coming to the rock and exposing the cochlea and vestibular nerve. The NVS fragments were removed, postfixed in osmium tetroxide, and embedded in the epoxy plastic resin Poly/Bed 812® (Polysciences Inc., Warrington, PA). Semi-thin transverse serial sections (0.5 μm) were made using a microtome MT6000-XL, RMC, Inc. and stained with toluidine blue. Morphology and morphometry were described and evaluated using the KS 400 application (Kontron 2.0, EchingBei, Munich, Germany) by macro, a computer program specially designed and developed for the study of the VIII nerve. The SVN was found to be devoid of epineurium, with only a thin conjunctive tissue layer. The myelin sheath of guinea pigs is relatively thin compared to the sensory and motor nerves found in mammals. The average fascicular area SVN was 0.19 ± 0.05 mm , with the largest area found to be 0.24 mm and the lowest was 0.12 mm . The average number of fibers was 5,753.00 ± 538 fibers. The density of myelinated fibers reached 32,316.08 ± 11,375.29 fibers/mm . Its diameter ranged from 1.0 to 9 μm and its peak was 3 μm. The measured results confirm the results of another study, indicating that the methodology is appropriate and reproducible. These findings are important for the evaluation of injured nerves in experimental models of peripheral neuropathy and basic ear disease.
Topics: Animals; Guinea Pigs; Vestibular Nerve; Male; Myelin Sheath; Cochlea
PubMed: 37461264
DOI: 10.1002/ar.25053 -
Journal of Lipid Research May 2024Contrast-enhanced computed tomography offers a nondestructive approach to studying adipose tissue in 3D. Several contrast-enhancing staining agents (CESAs) have been...
Contrast-enhanced computed tomography offers a nondestructive approach to studying adipose tissue in 3D. Several contrast-enhancing staining agents (CESAs) have been explored, whereof osmium tetroxide (OsO) is the most popular nowadays. However, due to the toxicity and volatility of the conventional OsO, alternative CESAs with similar staining properties were desired. Hf-WD 1:2 POM and Hexabrix have proven effective for structural analysis of adipocytes using contrast-enhanced computed tomography but fail to provide chemical information. This study introduces isotonic Lugol's iodine (IL) as an alternative CESA for adipose tissue analysis, comparing its staining potential with Hf-WD 1:2 POM and Hexabrix in murine caudal vertebrae and bovine muscle tissue strips. Single and sequential staining protocols were compared to assess the maximization of information extraction from each sample. The study investigated interactions, distribution, and reactivity of iodine species towards biomolecules using simplified model systems and assesses the potential of the CESA to provide chemical information. (Bio)chemical analyses on whole tissues revealed that differences in adipocyte gray values post-IL staining were associated with chemical distinctions between bovine muscle tissue and murine caudal vertebrae. More specific, a difference in the degree of unsaturation of fatty acids was identified as a likely contributor, though not the sole determinant of gray value differences. This research sheds light on the potential of IL as a CESA, offering both structural and chemical insights into adipose tissue composition.
PubMed: 38823780
DOI: 10.1016/j.jlr.2024.100572 -
Ecology and Evolution Apr 2024Comparative anatomy is an important tool for investigating evolutionary relationships among species, but the lack of scalable imaging tools and stains for rapidly...
Comparative anatomy is an important tool for investigating evolutionary relationships among species, but the lack of scalable imaging tools and stains for rapidly mapping the microscale anatomies of related species poses a major impediment to using comparative anatomy approaches for identifying evolutionary adaptations. We describe a method using synchrotron source micro-x-ray computed tomography (syn-μXCT) combined with machine learning algorithms for high-throughput imaging of Lepidoptera (i.e., butterfly and moth) eyes. Our pipeline allows for imaging at rates of ~15 min/mm at 600 nm resolution. Image contrast is generated using standard electron microscopy labeling approaches (e.g., osmium tetroxide) that unbiasedly labels all cellular membranes in a species-independent manner thus removing any barrier to imaging any species of interest. To demonstrate the power of the method, we analyzed the 3D morphologies of butterfly crystalline cones, a part of the visual system associated with acuity and sensitivity and found significant variation within six butterfly individuals. Despite this variation, a classic measure of optimization, the ratio of interommatidial angle to resolving power of ommatidia, largely agrees with early work on eye geometry across species. We show that this method can successfully be used to determine compound eye organization and crystalline cone morphology. Our novel pipeline provides for fast, scalable visualization and analysis of eye anatomies that can be applied to any arthropod species, enabling new questions about evolutionary adaptations of compound eyes and beyond.
PubMed: 38571794
DOI: 10.1002/ece3.11137