Analysis of brain biocompatibility of drug-releasing biodegradable microspheres by scanning and transmission electron microscopy

2001 ◽  
Vol 95 (3) ◽  
pp. 489-494 ◽  
Author(s):  
Joëlle Veziers ◽  
Maurice Lesourd ◽  
Christophe Jollivet ◽  
Claudia Montero-Menei ◽  
Jean-Pierre Benoit ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Brain Tissue ◽  
Neurotrophic Factors ◽  
Rat Striatum ◽  
Inert Material ◽  
Biodegradable Microspheres ◽  
Content Type ◽  
Transmission Electron ◽  
Fine Print

Object. Stereotactically guided implantation of biodegradable microspheres is a promising strategy for delivery of neurotrophic factors in a precise and spatially defined brain area. The goal in this study was to show the biocompatibility of poly(D,L,lactide-co-glycolide) microspheres with brain tissue at the ultrastructural level and to analyze the three-dimensional (3D) ultrastructure after intrastriatal implantation of these microparticles. Methods. Scanning and transmission electron microscopy were used to study the microspheres and their environment after implantation in an inert material (gelatin) and in the rat striatum. Observations were made at different time periods, ranging from 24 hours to 2 months postimplantation. Conclusions. The progressive degradation of the microspheres, with vacuolization, deformation, and shrinkage, was well visualized. This degradation was identical in microspheres implanted in the inert material and in the rat brain tissue, independent of the presence of macrophages. The studies preformed in the striatum permitted the authors to demonstrate the structural integrity of axons in contact with microspheres, confirming the biocompatibility of the polymer. Furthermore, scanning electron microscopy showed the preservation of the 3D ultrastructure of the striatum around the microparticles. These microparticles, which can be stereotactically implanted in functional areas of the brain and can release neurotrophic factors, could represent, for some indications, an alternative to gene therapy.

Oxyhemoglobin-induced apoptosis in cultured endothelial cells

1999 ◽  
Vol 91 (3) ◽  
pp. 459-465 ◽  
Author(s):  
Kotaro Ogihara ◽  
Alexander Y. Zubkov ◽  
David H. Bernanke ◽  
Adam I. Lewis ◽  
Andrew D. Parent ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Endothelial Cells ◽  
Time Dependent ◽  
Dependent Manner ◽  
Content Type ◽  
Aortic Endothelial Cells ◽  
Bovine Aortic Endothelial Cells ◽  
Transmission Electron ◽  
Fine Print

Object. Oxyhemoglobin (OxyHb) is one of the most important spasmogens for cerebral vasospasm that follows aneurysmal subarachnoid hemorrhage. The cytotoxic effect of OxyHb has been documented in endothelial and smooth-muscle cells; however, the pattern of cell death—necrosis or apoptosis—as the final stage of cell damage has not been demonstrated. This study was undertaken to determine if OxyHb induces apoptotic changes in cultured bovine aortic endothelial cells.Methods. Confluent bovine aortic endothelial cells were treated with OxyHb in a concentration- and time-dependent manner. Cell density was assayed by counting the number of cells that attached to culture dishes after exposure to OxyHb. To identify apoptotic changes, the investigators used three specific methods: DNA fragmentation (electrophoreses), the apoptotic body (transmission electron microscopy), and cleavage of poly (adenosine diphosphate ribose) polymerase (PARP [Western blotting]).Conclusions. Oxyhemoglobin decreased cell density in a concentration- and time-dependent manner. Analysis of DNA showed a pattern of internucleosomal cleavage characteristic of apoptosis (DNA ladder). Transmission electron microscopy demonstrated condensation of nuclei and apoptotic bodies in OxyHb-treated endothelial cells. Western blotting with the PARP antibody revealed that the 116-kD PARP was cleaved to the 85-kD apoptosis-related fragment. These results for the first time demonstrated that the OxyHb induces apoptosis in cultured endothelial cells.

Human neonatal hydrocephalus

1985 ◽  
Vol 63 (1) ◽  
pp. 56-63 ◽  
Author(s):  
Marc R. Del Bigio ◽  
J. Edward Bruni ◽  
H. Derek Fewer
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ependymal Cells ◽  
Foramen Of Monro ◽  
Content Type ◽  
Axonal Pathology ◽  
Transmission Electron ◽  
Cell Processes ◽  
Junctional Complexes ◽  
Fine Print

✓ An infant of 43 weeks gestational age with severe congenital hydrocephalus was operated on for removal of a subependymal astrocytoma in the region of the foramen of Monro. A biopsy of periventricular tissue was taken from the lateral ventricle for examination by scanning and transmission electron microscopy. The ependyma was largely denuded, with glial cell processes forming most of the ventricular lining. Many of the attenuated ependymal cells, however, had intact junctional complexes at areas of contact with other ependymal cells. Club-shaped unipolar cells, believed to be a previously undescribed form of immature ependymal cells, were found in the ventricular lining. Cerebrospinal fluid edema was present in the neuropil up to 60 µm from the ventricular lumen, but there was no obvious axonal pathology in the tissues examined.

scholarly journals In VitroEffects of Novel Ruthenium Complexes in Neospora caninum and Toxoplasma gondii Tachyzoites

2013 ◽  
Vol 57 (11) ◽  
pp. 5747-5754 ◽  
Author(s):  
Fabienne Barna ◽  
Karim Debache ◽  
Carsten A. Vock ◽  
Tatiana Küster ◽  
Andrew Hemphill
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Toxoplasma Gondii ◽  
Neospora Caninum ◽  
Ruthenium Complexes ◽  
Term Treatment ◽  
Content Type ◽  
Transmission Electron ◽  
Long Term Treatment

ABSTRACTUpon the screening of 16 antiproliferative compounds againstToxoplasma gondiiandNeospora caninum, two hydrolytically stable ruthenium complexes (compounds 16 and 18) exhibited 50% inhibitory concentrations of 18.7 and 41.1 nM (T. gondii) and 6.7 and 11.3 nM (N. caninum). To achieve parasiticidal activity with compound 16, long-term treatment (22 to 27 days at 80 to 160 nM) was required. Transmission electron microscopy demonstrated the rapid impact on and ultrastructural alterations in both parasites. These preliminary findings suggest that the potential of ruthenium-based compounds should thus be further exploited.

scholarly journals Antimicrobial Properties of a Chitosan Dextran-Based Hydrogel for Surgical Use

2011 ◽  
Vol 56 (1) ◽  
pp. 280-287 ◽  
Author(s):  
Manal A. Aziz ◽  
Jaydee D. Cabral ◽  
Heather J. L. Brooks ◽  
Stephen C. Moratti ◽  
Lyall R. Hanton
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Bacterial Species ◽  
Antimicrobial Properties ◽  
Sinus Surgery ◽  
Peptide Bonds ◽  
Content Type ◽  
E Coli ◽  
Transmission Electron

ABSTRACTA chitosan dextran-based (CD) hydrogel, developed for use in endoscopic sinus surgery, was tested for antimicrobial activityin vitroagainst a range of pathogenic microorganisms. The microdilution technique was used to determine minimum inhibitory, minimum bactericidal, and minimum fungicidal concentrations. In addition, the time-kill efficacy of CD hydrogel was determined for two bacterial species. Scanning and transmission electron microscopy were carried out to elucidate the antimicrobial mechanism of this compound. CD hydrogel was found to be effective againstStaphylococcus aureus,Streptococcus pyogenes,Escherichia coli, andClostridium perfringensat its surgical concentration of 50,000 mg/liter. Minimum bactericidal concentrations ranged from 2,000 to 50,000 mg/liter. Dextran aldehyde (DA) was found to be the antimicrobial component of the CD hydrogel with MBC ranging from 2,000 to 32,000 mg/liter.S. aureusappeared to be killed at a slightly faster rate thanE. coli. Candida albicansandPseudomonas aeruginosawere more resistant to CD hydrogel and DA. Scanning and transmission electron microscopy ofE. coliandS. aureusincubated with CD hydrogel and DA alone revealed morphological damage, disrupted cell walls, and loss of cytosolic contents, compatible with the proposed mode of action involving binding to cell wall proteins and disruption of peptide bonds. Motility and chemotaxis tests showedE. colito be inhibited when incubated with DA. The antibacterial activity of CD hydrogel may make it a useful postsurgical aid at other body sites, especially where there is a risk of Gram-positive infections.

scholarly journals Evaluation of Ultrasound-Induced Damage to Escherichia coli and Staphylococcus aureus by Flow Cytometry and Transmission Electron Microscopy

2016 ◽  
Vol 82 (6) ◽  
pp. 1828-1837 ◽  
Author(s):  
Jiao Li ◽  
Juhee Ahn ◽  
Donghong Liu ◽  
Shiguo Chen ◽  
Xingqian Ye ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Transmission Electron Microscopy ◽  
Flow Cytometry ◽  
Cytoplasmic Membrane ◽  
Ultrasound Treatment ◽  
Cellular Damage ◽  
Content Type ◽  
Transmission Electron

ABSTRACTAs a nonthermal sterilization technique, ultrasound has attracted great interest in the field of food preservation. In this study, flow cytometry and transmission electron microscopy were employed to investigate ultrasound-induced damage toEscherichia coliandStaphylococcus aureus. For flow cytometry studies, single staining with propidium iodide (PI) or carboxyfluorescein diacetate (cFDA) revealed that ultrasound treatment caused cell death by compromising membrane integrity, inactivating intracellular esterases, and inhibiting metabolic performance. The results showed that ultrasound damage was independent of initial bacterial concentrations, while the mechanism of cellular damage differed according to the bacterial species. For the Gram-negative bacteriumE. coli, ultrasound worked first on the outer membrane rather than the cytoplasmic membrane. Based on the double-staining results, we inferred that ultrasound treatment might be an all-or-nothing process: cells ruptured and disintegrated by ultrasound cannot be revived, which can be considered an advantage of ultrasound over other nonthermal techniques. Transmission electron microscopy studies revealed that the mechanism of ultrasound-induced damage was multitarget inactivation, involving the cell wall, cytoplasmic membrane, and inner structure. Understanding of the irreversible antibacterial action of ultrasound has great significance for its further utilization in the food industry.

scholarly journals Morphological Effect of the New Antifungal Agent ME1111 on Hyphal Growth of Trichophyton mentagrophytes, Determined by Scanning and Transmission Electron Microscopy

2016 ◽  
Vol 61 (1) ◽  
Author(s):  
Yayoi Nishiyama ◽  
Sho Takahata ◽  
Shigeru Abe
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Antifungal Agent ◽  
Structural Changes ◽  
Hyphal Growth ◽  
Trichophyton Mentagrophytes ◽  
Fungal Cell ◽  
Morphological Effect ◽  
Content Type ◽  
Transmission Electron

ABSTRACT The effects of ME1111, a novel antifungal agent, on the hyphal morphology and ultrastructure of Trichophyton mentagrophytes were investigated by using scanning and transmission electron microscopy. Structural changes, such as pit formation and/or depression of the cell surface, and degeneration of intracellular organelles and plasmolysis were observed after treatment with ME1111. Our results suggest that the inhibition of energy production by ME1111 affects the integrity and function of cellular membranes, leading to fungal cell death.

scholarly journals Ultrastructure Variability of the Exosporium Layer of Clostridium difficile Spores from Sporulating Cultures and Biofilms

2016 ◽  
Vol 82 (19) ◽  
pp. 5892-5898 ◽  
Author(s):  
Marjorie Pizarro-Guajardo ◽  
Paulina Calderón-Romero ◽  
Daniel Paredes-Sabja
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Clostridium Difficile ◽  
Detailed Knowledge ◽  
Spore Form ◽  
Content Type ◽  
Host Interactions ◽  
Definitive Evidence ◽  
Transmission Electron ◽  
Biofilm Development

ABSTRACTThe anaerobic sporeformerClostridium difficileis the leading cause of nosocomial antibiotic-associated diarrhea in developed and developing countries. The metabolically dormant spore form is considered the morphotype responsible for transmission, infection, and persistence, and the outermost exosporium layer is likely to play a major role in spore-host interactions during recurrent infections, contributing to the persistence of the spore in the host. A recent study (M. Pizarro-Guajardo, P. Calderón-Romero, P. Castro-Córdova, P. Mora-Uribe, and D. Paredes-Sabja, Appl Environ Microbiol 82:2202–2209, 2016,http://dx.doi.org/10.1128/AEM.03410-15) demonstrated by transmission electron microscopy the presence of two ultrastructural morphotypes of the exosporium layer in spores formed from the same sporulating culture. However, whether these distinct morphotypes appeared due to purification techniques and whether they appeared during biofilm development remain unclear. In this communication, we demonstrate through transmission electron microscopy that these two exosporium morphotypes are formed under sporulation conditions and are also present in spores formed during biofilm development. In summary, this work provides definitive evidence that in a population of sporulating cells, spores with a thick outermost exosporium layer and spores with a thin outermost exosporium layer are formed.IMPORTANCEClostridium difficilespores are recognized as the morphotype of persistence and transmission ofC. difficileinfections. Spores ofC. difficileare intrinsically resistant to all known antibiotic therapies. Development of spore-based removal strategies requires a detailed knowledge of the spore surface for proper antigen selection. In this context, in this work we provide definitive evidence that two types of spores, those with a thick outermost exosporium layer and those with a thin outermost exosporium layer, are formed in the sameC. difficilesporulating culture or during biofilm development.

scholarly journals Interspecies Microbial Fusion and Large-Scale Exchange of Cytoplasmic Proteins and RNA in a Syntrophic Clostridium Coculture

mBio ◽  
2020 ◽  
Vol 11 (5) ◽  
Author(s):  
Kamil Charubin ◽  
Shannon Modla ◽  
Jeffrey L. Caplan ◽  
Eleftherios Terry Papoutsakis
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Fusion ◽  
Large Scale ◽  
Cellular Material ◽  
Hybrid Cells ◽  
Content Type ◽  
Transmission Electron ◽  
Heterologous Cell ◽  
Material Exchange

ABSTRACT Microbial syntrophy is universal in nature, profoundly affecting the composition and function of microbiomes. We have recently reported data suggesting direct cell-to-cell interactions leading to electron and material exchange between the two microbes in the syntrophy between Clostridium ljungdahlii and C. acetobutylicum. Here, transmission electron microscopy and electron tomography demonstrated cell wall and membrane fusions between the two organisms, whereby C. ljungdahlii appears to invade C. acetobutylicum pole to pole. Correlative fluorescence transmission electron microscopy demonstrated large-scale exchange of proteins. Flow cytometry analysis captured the extent and dynamic persistence of these interactions. Dividing hybrid cells were identified containing stained proteins from both organisms, thus demonstrating persistence of cells with exchanged cellular components. Fluorescence microscopy and flow cytometry of one species with stained RNA and the other tagged with a fluorescent protein demonstrated extensive RNA exchange and identified hybrid cells, some of which continued to divide, while some were in an advanced C. acetobutylicum sporulation form. These data demonstrate that cell fusion enables large-scale cellular material exchange between the two organisms. Although unanticipated and never previously reported, these phenomena are likely widely distributed in nature, have profound implications for species evolution and the function of microbial communities, and could find utility in biotechnology. They may shed new light onto little-understood phenomena, such as antibiotic heteroresistance of pathogens, pathogen invasion of human tissues, and the evolutionary trajectory and persistence of unculturable bacteria. IMPORTANCE We report that two different bacterial organisms engage in heterologous cell fusion that leads to massive exchange of cellular material, including proteins and RNA, and the formation of persistent hybrid cells. The interspecies cell fusion observed here involves a syntrophic microbial system, but these heterologous cell fusions were observed even under nonstrict syntrophic conditions, leaving open the possibility that strict syntrophy may not be necessary for interspecies cell fusion and cellular material exchange. Formation of hybrid cells that contain proteins and RNA from both organisms is unexpected and unprecedented. Such fusion events are likely widely distributed in nature, but have gone undetected. The implications are profound and may shed light onto many unexplained phenomena in human health, natural environments, evolutionary biology, and biotechnology.

scholarly journals Interaction of Uranium with Bacterial Cell Surfaces: Inferences from Phosphatase-Mediated Uranium Precipitation

2016 ◽  
Vol 82 (16) ◽  
pp. 4965-4974 ◽  
Author(s):  
Sayali Kulkarni ◽  
Chitra Seetharam Misra ◽  
Alka Gupta ◽  
Anand Ballal ◽  
Shree Kumar Apte
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Bacterial Cells ◽  
Alkaline Ph ◽  
Cell Surfaces ◽  
Content Type ◽  
Geochemical Conditions ◽  
Uranyl Carbonate ◽  
Transmission Electron ◽  
Uranyl Phosphate

ABSTRACTDeinococcus radioduransandEscherichia coliexpressing either PhoN, a periplasmic acid phosphatase, or PhoK, an extracellular alkaline phosphatase, were evaluated for uranium (U) bioprecipitation under two specific geochemical conditions (GCs): (i) a carbonate-deficient condition at near-neutral pH (GC1), and (ii) a carbonate-abundant condition at alkaline pH (GC2). Transmission electron microscopy revealed that recombinant cells expressing PhoN/PhoK formed cell-associated uranyl phosphate precipitate under GC1, whereas the same cells displayed extracellular precipitation under GC2. These results implied that the cell-bound or extracellular location of the precipitate was governed by the uranyl species prevalent at that particular GC, rather than the location of phosphatase. MINTEQ modeling predicted the formation of predominantly positively charged uranium hydroxide ions under GC1 and negatively charged uranyl carbonate-hydroxide complexes under GC2. Both microbes adsorbed 6- to 10-fold more U under GC1 than under GC2, suggesting that higher biosorption of U to the bacterial cell surface under GC1 may lead to cell-associated U precipitation. In contrast, at alkaline pH and in the presence of excess carbonate under GC2, poor biosorption of negatively charged uranyl carbonate complexes on the cell surface might have resulted in extracellular precipitation. The toxicity of U observed under GC1 being higher than that under GC2 could also be attributed to the preferential adsorption of U on cell surfaces under GC1. This work provides a vivid description of the interaction of U complexes with bacterial cells. The findings have implications for the toxicity of various U species and for developing biological aqueous effluent waste treatment strategies.IMPORTANCEThe present study provides illustrative insights into the interaction of uranium (U) complexes with recombinant bacterial cells overexpressing phosphatases. This work demonstrates the effects of aqueous speciation of U on the biosorption of U and the localization pattern of uranyl phosphate precipitated as a result of phosphatase action. Transmission electron microscopy revealed that location of uranyl phosphate (cell associated or extracellular) was primarily influenced by aqueous uranyl species present under the given geochemical conditions. The data would be useful for understanding the toxicity of U under different geochemical conditions. Since cell-associated precipitation of metal facilitates easy downstream processing by simple gravity-based settling down of metal-loaded cells, compared to cumbersome separation techniques, the results from this study are of considerable relevance to effluent treatment using such cells.

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