Browsing by Subject "Transmission electron microscopy"

Now showing 1 - 7 of 7
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    Aggregation behaviour of gold nanoparticles in presence of chitosan
    (Springer, 2015-06-13) Fernández Espín, Vanesa ; Pamies, Ramón ; García de la Torre, José; García Montalbán, Mercedes; collado; Collado-González, Mar; Hernández Cifre, José Ginés; Díaz Baños, F. Guillermo; Víllora Cano, Gloria; Ingeniería Química
    Chitosan (CS) is a biocompatible polysaccharide with positive charge that is widely used as a coating agent for negatively charged nanoparticles. However, the types of structures that emerge by combining CS and anoparticles as well as their behaviour are still poorly understood. In this work, we characterize the nanocomposites formed by gold nanoparticles (AuNPs) and CS and study the influence of CS in the expected aggregation process that should experience those nanoparticles under the favourable conditions of low pH and high ionic strength. Thus, at the working CS concentration, we observe the existence of CS structures that quickly trap the AuNPs and avoid the formation of nanoparticle aggregates in environmental conditions that, otherwise, would lead to such an aggregation.
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    Brain endothelial cell activation and dysfunction associate with and contribute to the development of enlarged perivascular spaces and cerebral small vessel disease
    (Universidad de Murcia, Departamento de Biologia Celular e Histiologia, 2024) Hayden, Melvin Ray
    Multiple injurious stimuli to the brain’s endothelium results in brain endothelial cell activation and dysfunction (BECact/dys) with upregulation of inflammatory signaling cascades and a decrease in bioavailable nitric oxide respectively. These injurious stimuli initiate a brain injury and a response to injury wound healing genetically programed cascade of events, which result in cellular remodeling of the neurovascular unit and blood-brain barrier with increased inflammation and permeability. These remodeling changes also include the perivascular spaces that become dilated to form enlarged perivascular spaces (EPVS) that may be identified noninvasively by magnetic resonance imaging. These EPVS are associated with and considered to be a biomarker for cerebral small vessel disease (SVD) and a dysfunctional glymphatic system with impaired removal of neurotoxic waste, which ultimately results in neurodegeneration with impaired cognition and dementia. The penultimate section discusses the understudied role of venous cerebral circulation in relation to EPVS, SVD, and the vascular contribution to cognitive impairment (VCID). The focus of this review will be primarily on BECact/dys that associates with and contributes to the development of EPVS, SVD, and impaired glymphatic system efflux. Importantly, BECact/dys may be a key piece of the puzzle to unlock this complicated story of EPVS and SVD. Multiple transmission electron micrographs and illustrations will be utilized to depict anatomical ultrastructure and allow for the discussion of multiple functional molecular cascades.
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    Consecutive light microscopy, scanning-transmission electron microscopy and transmission electron microscopy of traumatic human brain oedema and ischaemic brain damage
    (Murcia : F. Hernández, 2001) Castejon, O.J.; Castejon, H.V.; Diaz, M.; Castellano, A.
    Cortical biopsies of 11 patients with traumatic brain oedema were consecutively studied by light microscopy (LM) using thick plastic sections, scanning-transmission electron microscopy ((S)TEM) using semithin plastic sections and transmission electron microscopy (TEM) using ultrathin sections. Samples were glutaraldehyde-osmium fixed and embedded in Araldite or Epon. Thick sections were stained with toluidine-blue for light microscopy. Semithin sections were examined unstained and uncoated for (S)TEM. Ultrathin sections were stained with uranyl and lead. Perivascular haemorrhages and perivascular extravasation of proteinaceous oedema fluid were observed in both moderate and severe oedema. Ischaemic pyramidal and non-pyramidal nerve cells appeared shrunken, electron dense and with enlargement of intracytoplasmic membrane compartment. Notably swollen astrocytes were observed in all samples examined. Glycogen-rich and glycogen-depleted astrocytes were identified in anoxic-ischaemic regions. Dark and hydropic satellite, interfascicular and perivascular oligodendrocytes were also found. The status spongiosus of severely oedematous brain parenchyma observed by LM and (S)TEM was correlated with the enlarged extracellular space and disrupted neuropil observed by TEM. The (S)TEM is recommended as a suitable technique for studying pathological processes in the central nervous system and as an informative adjunct to LM and TEM.
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    Gap junctions and expression of Cx36 Cx43 and Cx45 in the posterodorsal medial amygdala of adult rats
    (Universidad de Murcia, Departamento de Biologia Celular e Histiologia, 2020) Zancan, Mariana; Malysz, Tais; Moura, Dinara J.; Morás, Ana Moira; Steffens, Luiza; Rasia-Filho, Alberto
    The posterodorsal medial amygdala (MePD) has a synaptic organization that dynamically modulates reproduction and other social behaviors in rats. Discrete gap junctions between glial cells were previously reported in the MePD neuropil. Connexins (Cx) are components of gap junctions and indicative of cellular electrical coupling. Here, we report the ultrastructural occurrence of gap junctions between neurons in the MePD and demonstrate the expression and immunofluorescent labeling of Cx36, Cx43 and Cx45 in this subcortical area of adult male rats. Few neuronal gap junctions were found in the MePD and, when identified, occurred between dendrites. On the other hand, there is a diffuse presence and distribution of punctate labelling for the tested Cxs. Puncta were visualized isolated or forming clusters in the same focal plane of cell bodies or along the MePD neuropil. The Cx36 puncta were found in neurons, Cx43 in astrocytes and Cx45 in both neurons and astrocytes. Our data indicate the presence of few gap junctions and different Cxs composition in the MePD. Because Cxs can assemble, form hemichannel units and/or serve as transcriptional regulator, it is likely that additional modulation of intercellular communication can occur besides the chemical transmission in the MePD of adult rats.
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    Immunoreactions for P53 isoforms are associated with ultrastructural proliferative profiles in benign thyroid nodules
    (Universidad de Murcia. Departamento de Biología Celular e Histología, 2016) Concetta Trovato, Maria; Ruggeri, Rosaria Maddalena; Scardigno, Marco; Sturniolo, Giacomo; Vita, Roberto; Vitarelli, Enrica; Arena, Grazia; Gambadoro, Orazio; Sturniolo, Giovanni; Trimarchi, Francesco; Benvenga, Salvatore; Bourdon, Jean-Christophe; Cavallari, Vittorio
    Background: P53 isoforms originate from the alternative initiation of P53 gene translation through usage of an internal promoter located in intron 4. All P53 isoforms are spliced in intron 9 and may modulate cell proliferation and cell fate outcome in response to DNA damage. Aim: To examine immunoexpression of P53 isoforms in benign proliferative lesions occurring in multinodular thyroids and to assess the ultrastructural phenotype of P53 distribution in the thyrocytes of those lesions by electron microscopy. Materials and Methods: By immunohistochemistry and transmission electron microscopy (TEM), we evaluated 38 multinodular thyroids containing a total of 102 benign lesions: 38 nodular goiters (NG; colloid=20, parenchymatous=18), 52 follicular adenomas (FA) and 12 Hashimoto’s thyroditis (HT). FA were classified into 10 normo-follicular, 9 macro-follicular, 28 microfollicular and 5 solid variants. Results: Immunoreaction for P53 isoforms was observed in approximately 50% of all lesions, except macrofollicular variant FA (33%). At TEM analysis, immunoreactive NG, FA and TH lesions showed signs of proliferation by simultaneous appearance of dispersed chromatin, increased amounts of cytoplasmic organelles and dilation of the rough endoplasmic reticulum. TEM signs of apoptosis and proliferation were also detected in FA, but with different rates compared to NG. Conclusion: The immunohistochemical expression of P53 isoforms in NG, FA and HT suggests their role in the development of these lesions. Ultrastructural findings support the hypothesis that P53 immunoexpression correlates with reactive proliferative changes in thyrocytes.
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    Ultrastructural assessment of human periodontal ligament fibroblast interaction with bovine pericardium membranes: An in vitro study
    (Universidad de Murcia, Departamento de Biologia Celular e Histiologia, 2025) Bernardi, Sara; Marchetti, Enrico; Torge, Diana; Simeone, Davide; Macchiarelli, Guido; Bianchi, Serena; Biología Celular e Histología
    Research towards regenerative dentistry focused on developing scaffold materials whose high performance induces cell adhesion support and guides tissue growth. An early study investigated the proliferation abilities and attachment of human periodontal ligament fibroblasts (HPLFs) on two bovine pericardium membranes with different thicknesses, 0.2 mm and 0.4 mm. Following those published results, we examined the ultrastructure of HPLFs in contact with these membranes. The HPLFs were cultured in standard conditions, exposed to the tested materials, and, after 24 hours, subjected to transmission electron microscopy preparation. The examined parameters included the quality and distribution of mitochondria, Golgi apparatus, and the nucleus. HPLFs exposed to membranes showed ultrastructural changes. The cellular compartments aimed at protein synthesis and metabolism increased compared with the control. Unpaired t-test and one-way ANOVA showed that HPLFs exposed to membranes displayed an increase in the number of mitochondria (89.23±7.44 vs. 66.90±9.58; T1 and control; p<0.05 and 84.05±14.01 vs. 66.90±9.58; T2 and control; p<0.05). The reported ultrastructural evidence suggests an active synthesis state of HPLFs, probably triggered by the bovine collagen membrane, showing an active role of this material in the biology of the regeneration process.
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    Ultrastructural evidence of the evolutional process in malakoplakia
    (Universidad de Murcia, Departamento de Biologia Celular e Histiologia, 2020) Jung, Yeon Seung; Chung, Dong Yong; Kim, Eun Jin; Cho, Nam Hoon
    Context. Malakoplakia can be caused by incomplete digestion of Escherichia coli by lysosomes, leading to recurrent urinary tract infections and consequential mass-forming events that mimic tumors. Objectives. By using ultrastructural findings, we aimed to specify the process of phagolysosome to evoke malakoplakia. Design. We observed a series of processes to form a peculiar Michaelis-Gutmann (MG) body in three patients with malakoplakia and compared with xanthogranulomatous pyelonephritis. Results. The ultrastructural findings were realigned according to the sequence of events as pre-phagosomal, phagosomal, and post-phagosomal stages. For the mature MG body, numerous lysosomal aggregates targeting pathogens and subsequent incomplete digestion are prerequisite factors for the pre-phagosomal stage. Scattered lamellated residue is late evidence of the pre- phagosomal stage. Phagosomes can be formed by the fusion of multiple pathogens and multiple lysosomes. We utilized transmission and scanning electron microscopy to speculate on the process of phagolysosomal formation. Conclusion. The recognition of E. coli captured by phagosomes or partially damaged by lysosomal attack within the cell was recorded for the first time. Furthermore, SEM observation was performed on human tissue