The Reaction of Brain Structures with OsO4-Zinc-Iodide Stain

1971 ◽  
Vol 29 ◽  
pp. 272-273
Author(s):  
Werner J. Niklowitz
Keyword(s):  
Electron Microscope ◽  
Structural Changes ◽  
Mossy Fiber ◽  
Toxic Metal ◽  
Staining Technique ◽  
Brain Structures ◽  
Oxidase Inhibitor ◽  
Fiber Layer ◽  
Hippocampal Tissue ◽  
Zinc Iodide

After intoxication of rabbits with certain substances such as convulsant agents (3-acetylpyridine), centrally acting drugs (reserpine), or toxic metal compounds (tetraethyl lead) a significant observation by phase microscope is the loss of contrast of the hippocampal mossy fiber layer. It has been suggested that this alteration, as well as changes seen with the electron microscope in the hippocampal mossy fiber boutons, may be related to a loss of neurotransmitters. The purpose of these experiments was to apply the OsO4-zinc-iodide staining technique to the study of these structural changes since it has been suggested that OsO4-zinc-iodide stain reacts with neurotransmitters (acetylcholine, catecholamines).Domestic New Zealand rabbits (2.5 to 3 kg) were used. Hippocampal tissue was removed from normal and experimental animals treated with 3-acetylpyridine (antimetabolite of nicotinamide), reserpine (anti- hypertensive/tranquilizer), or iproniazid (antidepressant/monamine oxidase inhibitor). After fixation in glutaraldehyde hippocampal tissue was treated with OsO4-zinc-iodide stain and further processed for phase and electron microscope studies.

Evaluation of single-electron movies of glutamine synthetase molecules

1983 ◽  
Vol 41 ◽  
pp. 280-281
Author(s):  
W. Kunath ◽  
E. Zeitler ◽  
M. Kessel
Keyword(s):  
Electron Microscope ◽  
Glutamine Synthetase ◽  
Electron Irradiation ◽  
Structural Damage ◽  
Structural Changes ◽  
Single Electron ◽  
Continuous Series ◽  
Digital Recording ◽  
Recording Device ◽  
Low Exposure

The features of digital recording of a continuous series (movie) of singleelectron TV frames are reported. The technique is used to investigate structural changes in negatively stained glutamine synthetase molecules (GS) during electron irradiation and, as an ultimate goal, to look for the molecules' “undamaged” structure, say, after a 1 e/Å2 dose.The TV frame of fig. la shows an image of 5 glutamine synthetase molecules exposed to 1/150 e/Å2. Every single electron is recorded as a unit signal in a 256 ×256 field. The extremely low exposure of a single TV frame as dictated by the single-electron recording device including the electron microscope requires accumulation of 150 TV frames into one frame (fig. lb) thus achieving a reasonable compromise between the conflicting aspects of exposure time per frame of 3 sec. vs. object drift of less than 1 Å, and exposure per frame of 1 e/Å2 vs. rate of structural damage.

scholarly journals Glaucomatous Macular Vasculature: A Quantitative Analysis

2020 ◽  
Vol 9 (3) ◽  
pp. 185-197
Author(s):  
Pedro Arede ◽  
Joanna Przezdziecka-Dolyk ◽  
Fabian Debowy ◽  
Jacek Olszewski ◽  
Carla Fernandes ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Structural Changes ◽  
Open Angle Glaucoma ◽  
Major Axis ◽  
Foveal Avascular Zone ◽  
Control Group ◽  
Equivalent Diameter ◽  
Optical Coherence ◽  
Fiber Layer ◽  
Avascular Zone

Background: The aim of this study was to evaluate the characteristics of the macular vessel density (VD) and the foveal avascular zone (FAZ) in glaucoma quantitatively using the optical coherence tomography angiography (OCT-A). Methods: Twenty-five eyes of 13 patients with primary open angle glaucoma (POAG) and 12 eyes of 6 healthy participants were enrolled retrospectively. Functional visual field (VF) and structural Spectral-Domain optical coherence tomography (SD-OCT) Retinal Nerve Fiber Layer Thickness (RNFLT) were assessed in all participants. OCT-A was performed on a fovea centered, 15x10 degrees, macular region. OCT-A scans were processed with MATLAB software and automatically graded to define FAZ parameters. The parafoveal VD in the superficial and deep retinal vascular plexus (SVP and DVP) was analyzed by quadrant and circular segmented zones. Results: Foveal Avascular Zone -Major Axis Length (p=0.02), Area (p=0.04), Equivalent Diameter (p=0.04) and Perimeter (p=0.04) were significantly larger in glaucoma than the control group. Regarding SVP and DVP, the average macular total VD were lower in glaucoma patients compared to the control group (p<0.01; p<0.01). Additionally, the inner circular region (p=0.04; p<0.01 respectively for SVP and DVP) and all quadrants except for North had a lower VD in glaucoma group compared to the control group. Assessment of the total VD successfully predicted RNFLT (p<0.001) and was significantly associated with the probability of glaucoma (p=0.009). Conclusion: OCT-A parameters, namely the FAZ morphology and the macular VD, were associated with glaucomatous functional and structural changes. The macular VD showed a considerable diagnostic value. It may be a modern biomarker, representing microvascular network disruption of the macular perfusion in glaucoma.

scholarly journals MS optic neuritis-induced long-term structural changes within the visual pathway

2020 ◽  
Vol 7 (2) ◽  
pp. e665 ◽  
Author(s):  
Marc Pawlitzki ◽  
Marc Horbrügger ◽  
Kristian Loewe ◽  
Jörn Kaufmann ◽  
Roland Opfer ◽  
...  
Keyword(s):  
Optic Neuritis ◽  
Structural Damage ◽  
Structural Changes ◽  
Visual Pathway ◽  
System Structure ◽  
Pattern Reversal ◽  
Inner Plexiform Layer ◽  
Fiber Layer ◽  
History Of

BackgroundThe visual pathway is commonly involved in multiple sclerosis (MS), even in its early stages, including clinical episodes of optic neuritis (ON). The long-term structural damage within the visual compartment in patients with ON, however, is yet to be elucidated.ObjectiveOur aim was to characterize visual system structure abnormalities using MRI along with optical coherence tomography (OCT) and pattern-reversal visual evoked potentials (VEPs) depending on a single history of ON.MethodsTwenty-eight patients with clinically definitive MS, either with a history of a single ON (HON) or without such history and normal VEP findings (NON), were included. OCT measures comprised OCT-derived peripapillary retinal nerve fiber layer (RNFL) and macular ganglion cell/inner plexiform layer (GCIPL) thickness. Cortical and global gray and white matter, thalamic, and T2 lesion volumes were assessed using structural MRI. Diffusion-weighted MRI-derived measures included fractional anisotropy (FA), mean (MD), radial (RD), and axial (AD) diffusivity within the optic radiation (OR).ResultsMean (SD) duration after ON was 8.3 (3.7) years. Compared with the NON group, HON patients showed significant RNFL (p = 0.01) and GCIPL thinning (p = 0.002). OR FA (p = 0.014), MD (p = 0.005), RD (p = 0.007), and AD (p = 0.004) were altered compared with NON. Global gray and white as well as other regional gray matter structures did not differ between the 2 groups.ConclusionA single history of ON induces long-term structural damage within the retina and OR suggestive of both retrograde and anterograde neuroaxonal degeneration.

Visual field loss and structure–function relationships in optic neuritis associated with myelin oligodendrocyte glycoprotein antibody

2020 ◽  
pp. 135245852093728
Author(s):  
Romain Deschamps ◽  
Manon Philibert ◽  
Cedric Lamirel ◽  
Jerome Lambert ◽  
Vivien Vasseur ◽  
...  
Keyword(s):  
Visual Field ◽  
Optic Neuritis ◽  
Structural Damage ◽  
Structural Changes ◽  
Visual Field Loss ◽  
Visual Outcome ◽  
Myelin Oligodendrocyte Glycoprotein ◽  
Mean Deviation ◽  
Ophthalmological Examination ◽  
Fiber Layer

Background: A paradoxical discrepancy between severe peripapillary retinal nerve fiber layer (pRNFL) atrophy and good visual outcome had been reported in patients with myelin oligodendrocyte glycoprotein-immunoglobulin G (MOG-IgG)-associated optic neuritis (ON). However, only visual acuity (VA) was assessed. Objectives: To study visual field (VF) outcomes of patients with MOG-IgG-associated ON and evaluate the correlation between functional eye outcome and retinal structural changes assessed by optical coherence tomography. Methods: The records of 32 patients with MOG-IgG-associated ON who underwent ophthalmological examination at least 12 months after ON onset were reviewed. Degree of VF disability was determined by mean deviation (MD). Results: At final assessment (median, 35 months), 4.2% of 48 affected eyes (AE) had VA ⩽ 0.1, 40% had abnormal MD, and among AE with final VA ⩾ 1.0, 31% had mild to moderate damage. Thinning of the inner retinal layers was significantly correlated with MD impairment. Analysis demonstrated a threshold of pRNFL thickness (50 µm), below which MD was significantly worse (mean, −2.27 dB vs −17.72 dB; p = 0.0003). ON relapse was significantly associated with poor visual outcome assessed by MD. Conclusion: Functional impairment measured with VF is not rare, and MD assessment better reflects actual structural damage.

Structural changes in cells of Clostridium perfringens infected with a short-tailed bacteriophage

1971 ◽  
Vol 17 (3) ◽  
pp. 397-402 ◽  
Author(s):  
David E. Bradley ◽  
Judith F. M. Hoeniger
Keyword(s):  
Electron Microscope ◽  
Clostridium Perfringens ◽  
Structural Changes ◽  
Cell Envelope ◽  
Cell Lysis ◽  
Cell Periphery ◽  
Normal Cells ◽  
Phage Growth ◽  
Cooked Meat ◽  
In Cells

A culture of Clostridium perfringens strain 80 in cooked meat broth contained three types of cell: normal, long, and small round cells. The process of phage maturation and cell lysis was studied in all three forms using the electron microscope. In normal cells, the nucleoplasm first enlarged, then small clear areas, slightly larger than intracellular phages, appeared mainly around the cell periphery. The nucleoplasm dispersed and mature phage particles were formed. Subsequent lysis was caused by the breaking off of portions of the cell envelope leaving holes for the release of the contents. Long cells were also able to support phage growth.

Evaluation of inner retinal dimples and internal limiting membrane flap configuration after temporal inverted ILM flap technique

2020 ◽  
pp. 112067212094098
Author(s):  
Remzi Avci ◽  
Aysegul Mavi Yildiz ◽  
Sami Yilmaz
Keyword(s):  
Structural Changes ◽  
Imaging Modality ◽  
Internal Limiting Membrane ◽  
Fiber Layer ◽  
Flap Technique ◽  
Initial Surgery ◽  
En Face Oct ◽  
En Face ◽  
The Mean ◽  
Blue Reflectance

Purpose: To quantitatively evaluate structural changes associated with inner retinal dimples (IRDs) and qualitatively classify the internal limiting membrane (ILM) flap configuration after temporal inverted ILM flap technique using spectral domain optical coherence tomography (SD-OCT). Methods: Twenty-three eyes of 23 patients with successfully closed idiopathic, large (>400 μm) macular hole were enrolled. Patients were treated with pars plana vitrectomy followed by temporal inverted ILM flap technique. A complete ophthalmologic examination including cross sectional and en face OCT in addition to multicolor blue reflectance imaging of confocal scanning laser ophthalmoscopy (cSLO) was performed preoperatively and at postoperative month-12. The location, number, depth, and width of the IRDs were analyzed using blue reflectance images of multicolor cSLO and en face OCT. The ILM flap is also classified as smooth, wrinkled, and folded with en face OCT. Results: The mean number of IRDs visualized on en face OCT ( n = 23.08 ± 22.05) was statistically significantly higher compared with multicolor cSLO blue reflectance module (5.91 ± 10.58; p < 0.001). The mean depth of IRDs measured on en face OCT was 8.08 ± 3.1 μm (3–14 μm) which referred to the nerve fiber layer. The final visual acuity was associated with neither ILM flap configuration ( p = 0.408), nor number of the IRDs on en face OCT ( p = 0.112). Conclusion: En face OCT is a novel imaging modality that offers improved visualization and accuracy in identifying the features of the IRDs and the ILM flap. Additionally, it provides clear visualization of the vitreoretinal interface to distinguish whether ILM was peeled or not in the initial surgery.

scholarly journals Persistent activity in a cortical-to-subcortical circuit: bridging the temporal gap in trace eyelid conditioning

2012 ◽  
Vol 107 (1) ◽  
pp. 50-64 ◽  
Author(s):  
Jennifer J. Siegel ◽  
Brian Kalmbach ◽  
Raymond A. Chitwood ◽  
Michael D. Mauk
Keyword(s):  
Eyelid Conditioning ◽  
Mossy Fiber ◽  
Trace Conditioning ◽  
Brain Structures ◽  
Learning Activity ◽  
Persistent Activity ◽  
Trace Interval ◽  
Cerebellar Learning ◽  
Response Expression

We have addressed the source and nature of the persistent neural activity that bridges the stimulus-free gap between the conditioned stimulus (CS) and unconditioned stimulus (US) during trace eyelid conditioning. Previous work has demonstrated that this persistent activity is necessary for trace eyelid conditioning: CS-elicited activity in mossy fiber inputs to the cerebellum does not extend into the stimulus-free trace interval, which precludes the cerebellar learning that mediates conditioned response expression. In behaving rabbits we used in vivo recordings from a region of medial prefrontal cortex (mPFC) that is necessary for trace eyelid conditioning to test the hypothesis that neurons there generate activity that persists beyond CS offset. These recordings revealed two patterns of activity during the trace interval that would enable cerebellar learning. Activity in some cells began during the tone CS and persisted to overlap with the US, whereas in other cells, activity began during the stimulus-free trace interval. Injection of anterograde tracers into this same region of mPFC revealed dense labeling in the pontine nuclei, where recordings also revealed tone-evoked persistent activity during trace conditioning. These data suggest a corticopontine pathway that provides an input to the cerebellum during trace conditioning trials that bridges the temporal gap between the CS and US to engage cerebellar learning. As such, trace eyelid conditioning represents a well-characterized and experimentally tractable system that can facilitate mechanistic analyses of cortical persistent activity and how it is used by downstream brain structures to influence behavior.

Sign in / Sign up

Export Citation Format

Share Document