Incidence of subcortical lesions not increased in nonarteritic ischemic optic neuropathy on magnetic resonance imaging.
Explore the source record for details and available documents.
Cerebrovascular Disorders↗
SEARCH · Search PubMed
Results for “Optical imaging”
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Nuclear and cytoplasmic Ca2+ signals in developing rat dorsal root ganglion neurons studied in excised tissue.
Confocal microscopy and the Ca(2+)-sensitive fluorescent dye fluo-3 were used to study subcellular Ca2+ signals in embryonic, neonatal, and adult dorsal root ganglion (DRG) neurons in excised dorsal root ganglia. Optical images obtained from isolated whole embryonic and neonatal ganglia revealed a marked variability in the resting Ca2+ signals of different neurons as compared to signals in adult neurons which were uniformly faint. Many of the embryonic and neonatal neurons displayed nuclear Ca2+ signals at rest which were larger than those in the cytoplasm. Embryonic DRG neurons showed a significant increase in nuclear and cytoplasmic fluorescence in response to depolarization with elevated extracellular potassium or electrical stimulation. A single brief electrical stimulus was sufficient to elicit nuclear Ca2+ signals in a subset of the embryonic neurons. The depolarization-induced Ca2+ signals were blocked by removal of extracellular Ca2+, but not by treatment with 2,5-di (tert-butyl)-1,4 benzohydroquinone (DTBHQ), a compound which depletes intracellular Ca2+ stores. The intensity of the depolarization-induced Ca2+ signals declined significantly between the late embryonic (E18-E20) and early postnatal time periods (P0-P1). The nuclear and cytoplasmic Ca2+ signals of the embryonic DRG neurons in the excised tissue preparation occur at a time of intense target innervation, suggesting a role for Ca2+ signals in the development and maturation of rat DRG neurons.
Aniline Compounds↗
A learned odor decreases the number of Fos-immunopositive granule cells in the olfactory bulb of young rats.
Olfactory stimulation evokes a column of activity within the olfactory bulb extending from the glomerular layer to the granule cell layer that can be visualized with 2-deoxyglucose autoradiography, optical imaging, Fos protein immunohistochemistry and c-fos mRNA in situ hybridization. The Fos response to odors is typified by the activity of relatively few juxtaglomerular cells, which often occur in foci, and a large number of granule cells extending through much of the bulb. In this study, we characterized the granule cell response to an odor for which young rats had acquired a preference. Fos-like immunoreactive granule cells were quantified by image analysis, and densely stained cells were counted in a region previously shown to be responsive to peppermint odor. We found that odor-trained pups have about half the number of Fos-immunopositive superficial granule cells which respond to a learned odor than do control pups. We then determined whether there was a correlation between the juxtaglomerular cell response and the response of the superficial granule cells deep to those glomerular layer cells. We found a positive correlation between the number of juxtaglomerular cells and the number of granule cells demonstrating Fos immunoreactivity in both control and trained pups, a relationship that changed with early olfactory training.
Animals↗
Optical monitoring of movements in small animals and in semi-intact preparations.
A system has been developed for monitoring motor patterns both in small animals and in semi-intact preparations. Using a video recording system, the optical image of the selected object is projected onto a TV monitor to which is attached a pair of photosensitive resistors or diodes. The signals from the photosensor are amplified, filtered prior to being recorded, or stored using commercially available data capture systems. Use of the paired photosensitive elements allows us to avoid changes in background illumination, using a differential amplification function, during different patterns of activity of monitored organs or animals and also allows us to record activity from several different organs or systems simultaneously. The simplicity of the system enables us to perform simultaneous monitoring of both effector movements and neuronal activity via multi-channel microelectrode recordings. We have tested this system using semi-intact preparations of the freshwater pulmonate snail, Lymnaea stagnalis. Examples of different types of recordings are presented.
Animals↗
Specific effects of retinoic acid on the skeletal morphogenesis of the 11-day mouse embryo forelimb bud in vitro.
Using our improved method for culturing 11-day mouse forelimb buds in vitro, we have investigated the effects of a local application of all-trans-retinoic acid (RA) on growth, cartilaginous differentiation and skeletal patterning in the mammalian limb bud. Carrier implants of catgut impregnated with DMSO or various doses of RA in DMSO were inserted at the apex of the buds in the proximo-distal axis just beneath the apical ectodermal ridge. After 6 days of culture, cartilaginous skeletons were stained and explants were processed for morphological analysis and quantitative study using computerized optical image analysis. Buds treated with low doses of RA exhibited stimulated growth and chondrogenesis. Moreover, hypertrophied and fused metacarpals were seen within explants treated with the lowest dose. High doses strongly inhibited growth and skeletal morphogenesis. An intermediate dose sustained cartilaginous differentiation at the same level as low doses, but concomitantly disturbed the skeletal pattern. These results are discussed considering reported RA effects on other experimental systems including avian limb bud as an in vivo model or cell cultures as an in vitro simplified model.
Animals↗
Abnormal collagen fibril structure as studied by electron microscopy.
Transmission electron microscopy has emerged as an ideal tool for the study and diagnosis of various disorders that involve collagen, since the information obtained by this technique is at the ultrastructural level. Structural alterations of collagen fibrils brought about by these disorders are discussed. The positive staining pattern of such fibrils is also investigated. In addition, this review describes how quantitative studies of electron-optical images from abnormal collagen fibrils can lead to information about the changes produced by collagen defects which relate to molecular or fibril architecture.
Animals↗
Patterns of excitation and inhibition evoked by horizontal connections in visual cortex share a common relationship to orientation columns.
Combined optical imaging and electrophysiological techniques were used to assess directly the functional nature of long-range excitatory and inhibitory synaptic interactions between orientation columns in area 17 of ferret visual cortex. A significant correlation was found between the layout of iso-orientation columns and the pattern of evoked synaptic inputs between cortical sites: the largest-amplitude inhibitory and excitatory synaptic responses were evoked in single neurons when stimulation and recording electrodes were located in orientation columns sharing the same angle preference. Both excitatory and inhibitory synaptic responses decreased in amplitude when stimulation and recording electrodes were located in orientation columns with orthogonal angle preferences. Changing the stimulus intensity altered the balance of evoked excitation and inhibition without changing the columnar specificity of inputs. These results directly demonstrate that horizontal connections modulate both excitatory and inhibitory synaptic interactions between iso-orientation columns.
6-Cyano-7-nitroquinoxaline-2,3-dione↗
Region-dependent asymmetrical or symmetrical variations in the oxygenation and hemodynamics of the brain due to different mental stimuli.
The present paper demonstrates region-dependent variations in the oxygenation and hemodynamics of the brain hemispheres due to three different types of mental stimulation. The variations were observed with a four-channel optical imaging system using tissue-transparent near-infrared light and described changes from baseline of both the hemoglobin oxygenation state and blood volume during three kinds of psychological or mental tasks. During the mirror drawing task, a lateralized hemisphere response (the dominant hemisphere response pattern) was observed in 57% of 14 right handed volunteers in the frontal region (Brodmann's area 10), while in the temporal region (area 38), 80% showed the bilateral response pattern. A large majority of the subjects showed the bilateral response pattern in the frontal and temporal regions while calculating. A smaller majority showed this while looking at anatomical charts, though 30% did not show any response at all in the temporal region. This showed that there were region-dependent asymmetrical or symmetrical variations of the oxygen delivery-oxygen utilization relationship due to different types of mental stimuli.
Adult↗
New life in an old structure: the development of synaptic pathways in the spinal cord.
The study of the formation of synaptic circuits within the spinal cord has been hampered by the absence of accessible experimental preparations and suitable techniques. Recently, two new preparations have been described for following spinal development in vitro: slices of embryonic rat spinal cord co-cultured with sensory ganglia and myotubes, and cultures of the entire central nervous system of neonatal opossums. Optical imaging techniques have revealed spontaneous synchronous increases of Ca2+ levels in groups of spinal neurons. The widespread electrical coupling among developing spinal neurons, which may contribute to these synchronous bursts, becomes highly restricted as development proceeds. Both phenomena may play central roles in the formation of specific patterns of synaptic connections.
Animals↗
Dendritic calcium dynamics.
Further characterization of the biochemical components that contribute to calcium handling, together with advances in optical imaging of ion concentration, are providing quantitative information on the dynamics of calcium in the dendrites of neurons in tissue culture, brain slices and in vivo. It has recently been demonstrated that strong spatial gradients and transient calcium elevations result from the geometry and membrane properties of dendrites. These studies are adding to our understanding of calcium's role in synaptic plasticity and in shaping the electrophysiological properties of neurons.
Animals↗
Structure and molecular organization of the centromere-kinetochore complex.
For over a century, the terms centromere and kinetochore have been used interchangeably to describe a complex locus on eukaryotic chromosomes that attaches chromosomes to spindle fibres and facilitates chromosome movement in mitosis and meiosis. This region has become the focus of research aimed at defining the mechanism of chromosome segregation. A variety of new molecular probes and vastly improved optical-imaging technology have provided much new information on the structure of this locus and raised new hopes that an understanding of its function may soon be at hand.
Journal Article↗
Purification method directly influences effectiveness of an epidermal growth factor-coupled targeting agent for noninvasive tumor detection in mice.
Receptor targeting is an effective method of enhancing fluorescence signal in tumors for optical imaging. We previously used epidermal growth factor (EGF) conjugated to IRDye 800CW to detect and track orthotopic prostate tumors in mice. In this study, our goal was to identify a reliable assay for targeting agent integrity in vitro that correlated with signal strength in vivo. Binding of IRDye 800CW EGF to intact A431 human epidermoid carcinoma cells was quantified in a microplate assay. Specificity was confirmed by competition with unlabeled EGF or monoclonal antibody blocking. Biological activity of intact and damaged targeting agents relative to unlabeled EGF was determined by binding and stimulation of extracellular signal-regulated kinase (ERK) phosphorylation. Both assays indicated a reduction of up to 60% of the fluorescence intensity with damaged agents. Using a research prototype imaging system optimized for IRDye 800CW detection, we compared the efficacy of intact and damaged targeting agents for imaging subcutaneous tumors in mice. In live animal images and in sections of the excised tumors, damaged targeting agents consistently yielded diminished fluorescence signals corresponding to the reduction observed in microplate assays. This is the first study to directly correlate targeting agent signal strength in whole cell binding, In-Cell Western, and in vivo near-infrared imaging.
Animals↗
In vitro induction of differentiation by retinoic acid in an immortalized olfactory neuronal cell line.
In this study, we used a neuronal cell line generated by transfection of rat olfactory epithelium with immortalizing recombinant oncogene E1A of adenovirus-2. The resulting 13.S.1.24 line of transformed cells expressed an antigenic phenotype of olfactory neuronal progenitors. Time-dependency assessments over 1 week of treatment indicated that apoptosis and differentiation induced by retinoic acid (RA) were concomitant. Indeed, RA altered the cell proliferation rate, but it also stimulated differentiation of surviving 13.S.1.24 cells into bipolar olfactory marker protein-immunoreactive neurons. To characterize the nature of the cells we used immunocytochemistry, optical imaging, scanning electron microscopy and atomic force microscopy.
Adenylyl Cyclases↗
Bionanotechnology progress and advances.
Advances in the nanotechnology research have provided a new set of research tools, materials, structures, and systems for biological and medical research and applications. These nanotechnologies include the application of fluorescent quantum dots for optical imaging, the design of metallic nanoparticle surfaces for ultrasensitive biomolecular fingerprinting, and the use of nanostructures as hyperthermia agents for cancer therapy. Unlike conventional technologies, unique properties can be incorporated into nanometer-size particles, structures, and systems simply by changing their size, shape, and composition. Because of the tunable properties, biologists and clinicians could custom-design a material for a specific research need. In this review article, we highlight the recent advances and progress in Bionanotechnology research as well as provide future perspective on this integrative field.
Biotechnology↗
Electrospun fine-textured scaffolds for heart tissue constructs.
The structural and functional effects of fine-textured matrices with sub-micron features on the growth of cardiac myocytes were examined. Electrospinning was used to fabricate biodegradable non-woven poly(lactide)- and poly(glycolide)-based (PLGA) scaffolds for cardiac tissue engineering applications. Post-processing was applied to achieve macro-scale fiber orientation (anisotropy). In vitro studies confirmed a dose-response effect of the poly(glycolide) concentration on the degradation rate and the pH value changes. Different formulations were examined to assess scaffold effects on cell attachment, structure and function. Primary cardiomyocytes (CMs) were cultured on the electrospun scaffolds to form tissue-like constructs. Scanning electron microscopy (SEM) revealed that the fine fiber architecture of the non-woven matrix allowed the cardiomyocytes to make extensive use of provided external cues for isotropic or anisotropic growth, and to some extent to crawl inside and pull on fibers. Structural analysis by confocal microscopy indicated that cardiomyocytes had a preference for relatively hydrophobic surfaces. CMs on electrospun poly(L-lactide) (PLLA) scaffolds developed mature contractile machinery (sarcomeres). Functionality (excitability) of the engineered constructs was confirmed by optical imaging of electrical activity using voltage-sensitive dyes. We conclude that engineered cardiac tissue structure and function can be modulated by the chemistry and geometry of the provided nano- and micro-textured surfaces. Electrospinning is a versatile manufacturing technique for design of biomaterials with potentially reorganizable architecture for cell and tissue growth.
Absorbable Implants↗
Spatiotemporal chemical dynamics in living cells: from information trafficking to cell physiology.
Biological thought in the 20th century was dominated by the study of structures at increasingly minute levels. For biology to advance beyond structural reductionism and contribute its full measure to clinical care, living biological structures must be understood in the context of their collective chemical processes at the relevant chemical time-scales. Using high-speed fluorescence microscopy, we have studied intra- and inter-cellular signaling using shutter speeds ( approximately 100 ns) that remove the effects of wave motion and diffusion from optical images. By collecting a series of such images, stop-action movies of signal trafficking in living cells are created; these have revealed a new level of spatiotemporal chemical organization within cells. Numerous types of chemical waves have been found in living cells expressing a great variety of physical properties. In this article I will review some of these basic findings, discuss these events in the context of information trafficking, and illustrate the potential implications of this work in medicine.
Calcium Signaling↗
Spatial frequency-dependent feedback of visual cortical area 21a modulating functional orientation column maps in areas 17 and 18 of the cat.
The feedback effect of activity of area 21a on orientation maps of areas 17 and 18 was investigated in cats using intrinsic signal optical imaging. A spatial frequency-dependent decrease in response amplitude of orientation maps to grating stimuli was observed in areas 17 and 18 when area 21a was inactivated by local injection of GABA, or by a lesion induced by liquid nitrogen freezing. The decrease in response amplitude of orientation maps of areas 17 and 18 after the area 21a inactivation paralleled the normal response without the inactivation. Application in area 21a of bicuculline, a GABAa receptor antagonist caused an increase in response amplitude of orientation maps of area 17. The results indicate a positive feedback from high-order visual cortical area 21a to lower-order areas underlying a spatial frequency-dependent mechanism.
Animals↗
Integration of neural responses originating from different regions of the cortical somatosensory map.
The neural pathways responsible for detecting peripheral tactile stimuli are well known; however, the interactions between different somatosensory regions have been less well investigated. This study demonstrates how the contralateral sensory response of rat barrel cortex to whisker stimulation is affected by stimulation of contralateral forepaw and ipsilateral whisker and forepaw. The barrel cortex in the right hemisphere was located using optical imaging. A 16-channel multielectrode was used to measure field potentials evoked by contralateral electrical stimulation of the whisker pad. A standard response in the right barrel cortex to single pulse electrical stimulation of the contralateral whisker pad was modulated by applying conditioning stimulation to one of three other regions of the body (the ipsilateral whisker pad, the ipsilateral or contralateral forepaws). In conditions where the standard contralateral whisker stimulus preceded the conditioning pulse, the size of response was identical to when it was stimulated alone. However, when the ipsilateral whisker and contralateral forepaw conditioning stimuli preceded the contralateral whisker pad stimulation, up to a 35% reduction in the contralateral whisker response was observed. These results confirm and extend previous studies [Proc. Natl. Acad. Sci. U. S. A. 97 (2000) 11026-11031; J. Neurosci. 21 (2001) 5251-5261], which show bilateral integration of neural activity within the rat somatosensory system. Furthermore, the longer latency of the inhibition following stimulation of the contralateral forepaw suggests the possible involvement of extracortical circuitry.
Animals↗