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PubMed1988

Optical recording of electrical activity from axons and glia of frog optic nerve: potentiometric dye responses and morphometrics.

Voltage-sensitive dyes were used to study the changes in membrane potential in axons and glial cells of the frog optic nerve following electrical stimulation. The lack of a signal in the unstained nerve and the multiphasic action spectra after staining indicated that the optical responses were from the extrinsic dyes. Changes in dye absorption and fluorescence had rapid and slow phases. The rapid phases resulted from action potentials in myelinated and unmyelinated axons. The kinetics of the slow phase of the optical response were similar to the depolarization recorded from the glial cells with intracellular electrodes. The ratio of the amplitudes of the fast and slow phases was characteristic for each type of dye. Pharmacological analysis of the action potential of the unmyelinated axons revealed tetrodotoxin-sensitive sodium channels and 4-aminopyridine-sensitive potassium channels. Repeated exposure of the stained preparation to light led to photodynamic damage as shown by a block of recovery of the glial depolarization. An electron microscopic morphometric study of the nerve was carried out in an effort to understand the contribution of the various anatomical elements to the compound optical response. The ratio of unmyelinated axon membrane to glial membrane was much greater than was the ratio of the fast and slow components of the signal, suggesting that the dyes either had a higher affinity for glial membrane or did not penetrate the nerve uniformly.

4-Aminopyridine↗
PubMed1979

Cell death and optic fiber penetration in the optic stalk of the chick.

The role of dying cells in the optic stalk in relation to retinal fiber migration was investigated in the chick embryo. Cell death was analysed at various stages of development by counting pycnotic nuclei and also by the Gomori acid phosphatase reaction, while nerve fibers were visualised by the Bodian method. A wave of cell death, beginning in the neural retina at stage 18 and advancing with time through the stalk towards the diencephalon, occurred simultaneously or slightly prior to differentiation and migration of ganglion cell axons. Cell death stopped and gliogenesis occurred in the stalk after penetration by retinal fibers. Cell death occurred in the stalk even when fiber penetration was prevented by optic cup ablation. In this case, necrosis ensued until almost complete degeneration of the stalk, usually within three days after the operation, and gliogenesis did not occur. As the stalk degenerated, its cells became heavily pigmented. These observations suggest that the onset of cell death in the optic stalk is determined prior to and independently of retinal fiber penetration. On the other hand, cessation of cell death and subsequent gliogenesis occur only in the presence of ingrowing optic fibers.

Acid Phosphatase↗
PubMed2006

Determination of characteristics of degenerative joint disease using optical coherence tomography and polarization sensitive optical coherence tomography.

BACKGROUND AND OBJECTIVES: Previous studies have demonstrated that optical coherence tomography (OCT) could be used to delineate alterations in the microstructure of cartilage, and have suggested that changes in the polarization state of light as detected by OCT could provide information on the birefringence properties of articular cartilage as influenced by disease. In this study we have used both OCT and polarization sensitive optical coherence tomography (PS-OCT) technologies to evaluate normal and abnormal bovine articular cartilage according to established structural, organizational, and birefringent characteristics of degenerative joint disease (DJD) in order to determine if this technology can be used to differentiate various stages of DJD as a minimally invasive imaging tool. MATERIALS AND METHODS: Fresh bovine femoral-tibial joints were obtained from an abattoir, and 45 cartilage specimens were harvested from 8 tibial plateaus. Whole ex vivo specimens of normal and degenerative articular cartilage were imaged by both OCT and PS-OCT, then fixed and processed for histological evaluation. OCT/PS-OCT images and corresponding histology sections of each specimen were scored according to a modified Mankin structural grading scale and compared. RESULTS: OCT and PS-OCT imaging allowed structural evaluation of intact articular cartilage along a 6 mm surface length to a depth of 2 mm with a transverse resolution of 12 microm and an axial resolution of 10 microm. The OCT and PS-OCT images demonstrated characteristic alterations in the structure of articular cartilage with a high correlation to histological evaluation (kappa = 0.776). The OCT images were able to demonstrate early to advanced structural changes of articular cartilage while the optical phase retardation images obtained by PS-OCT imaging were able to discriminate areas where disorganization of the cartilage matrix was present, however, these characteristics are much different than those reported where OCT images alone were used to characterize tissue birefringence. No evidence of differences in OCT or PS-OCT images were detected between specimens of similar structural characteristics where proteoglycan was judged present or absent by safranin-O Fast Green staining. CONCLUSIONS: The combined use of OCT and PS-OCT technologies to obtain images from a single system is able to demonstrate and discriminate between characteristics of very early stages of surface irregularities not previously reported for OCT imaging, to deep clefts and collagen matrix disorganization for tissue at depths of up to 2 mm with good correlation to histology. PS-OCT and accumulated optical phase retardation images of articular cartilage as constructed from alterations in Stokes vector parameters appear to give a valuable but different assessment of alterations in tissue birefringence and organization than have been reported for OCT images obtained with the use of polarized or non-polarized light sources. This is the first time that alterations in the polarization state of light reflected from within the tissue have been demonstrated to be consistent with changes observed in the orientation and organization of the collagen matrix in advanced stages of DJD. The degree of phase transformation of light reflected from within the tissue as determined by PS-OCT imaging does not appear to be altered by the presence or absence of proteoglycan.

Animals↗
PubMed1994

Non-monotonic decay of excitatory synaptic transmission in the frog optic tectum following repetitive stimulation of the optic nerve in vitro.

The monosynaptic field excitatory postsynaptic potentials (EPSPs) evoked in the optic tectum of the frog (Rana remporaria) in vitro by different patterns of stimulation of the contralateral optic nerve were studied using extracellular recording. Pulse trains at frequencies of less than or equal to 0.033 Hz elicited field potentials of stable amplitude, whereas in the range 0.33-1.0 Hz EPSPs showed a depression in the first few responses subsequent to the first one, followed by a partial recovery and a final decline to a steady level. When the interpulse interval was less than 200 ms, paired-pulse monosynaptic facilitation was found. Decrease in the external Ca2+ concentration, or in the stimulation intensity or application of picrotoxin reversibly produced a monotonically decreasing EPSP amplitude, suggesting that a local neuronal circuit was controlling the development of synaptic fatigue. A simple model based on the combined effects of depletion of excitatory transmitter stores plus activation of a local inhibitory circuit was found to provide a simulation which closely resembled the experimentally observed pattern of synaptic fatigue. The present study suggests that an inhibitory synaptic process contributed to the non-monotonic decay of excitatory transmission in the frog optic tectum, following repetitive stimulation of the optic nerve.

Animals↗
PubMed1993

Infantile cerebello-optic atrophy. Neuropathology of the progressive encephalopathy syndrome with edema, hypsarrhythmia and optic atrophy (the PEHO syndrome).

Uniform neuropathological changes are described in eight cases of the progressive encephalopathy syndrome with edema, hypsarrhythmia and optic atrophy (PEHO syndrome). Two of the autopsied patients were sisters and two other cases were familial. Macroscopically, cerebral and pronounced cerebellar atrophy was seen, the essential histopathological lesions being confined to the cerebellar cortex and the optic nerve. There was a severe neuronal loss in the inner granular layer of the cerebellum. The Purkinje cells were relatively preserved in number although reduced in size, deformed and slightly disaligned. Their dendrites were horizontally oriented and the proximal axons contained abundant torpedoes. The molecular layer was narrow. The optic nerves were atrophic. Serial neuroimaging studies showed that the disease process is operative during the postnatal period, although a prenatal onset cannot be excluded. An aberrant expression of immunoreactivity against the 200-kDa neurofilament polypeptide in Purkinje cell perikarya indicated disorganization of the cytoskeleton of these cells. The combination of clinical and pathological features of our patients differs from that observed in the few published cases of so-called primary degeneration of the granular layer. Infantile cerebello-optic atrophy, clinically characterized by seizures, blindness and early arrest in psychomotor development, thus seems to constitute a new autosomal recessive disorder.

Atrophy↗
PubMed1988

Physiological and anatomical identification of the nucleus of the optic tract and dorsal terminal nucleus of the accessory optic tract in monkeys.

Physiological and anatomical criteria were used to clearly establish the existence of a pretectal relay of visual information to the ipsilateral inferior olive in the macaque monkey. After injection of horseradish peroxidase into the inferior olivary nucleus, retrogradely labelled neurons were found in the nucleus of the optic tract (NOT) and the dorsal terminal nucleus of the accessory optic tract (DTN). The labelled cells were distributed in a sparse band arching below the margin of the brachium of the superior colliculus between the dorsal and lateral borders of the brainstem at the caudal edge of the pulvinar. Various types of cells could be distinguished. More superficially the cells were extremely spindle shaped, cells deeper within the midbrain had more compact somata. NOT-DTN neurons in the same region were also found to respond with short latencies to electrical stimulation of both the inferior olive and the optic chiasm. All neurons in the NOT-DTN which were antidromically activated from the inferior olive were also found to have direction specific binocular visual responses. Such neurons were excited by ipsiversive motion and suppressed by contraversive motion, regardless of whether large area random dot stimuli moved across the visual field or small single dots moved across the fovea. Direct retinal input to these neurons was via slowly conducting fibers (3-9 m/s) from the monkey's optic tract conduction velocity spectrum. As shown previously for non-primates, NOT-DTN cells may also in the monkey carry a signal representing the velocity error between stimulus and retina (retinal slip), and relay this signal into the circuitry mediating the optokinetic reflex.

Animals↗
PubMed1996

The subarachnoid space surrounding the optic nerves. An ultrasound study of the optic nerve sheath.

The presence of enlarged optic nerve sheaths (ONS) suggests that raised intracranial pressure is transmitted to the perineural subarachnoid space (SAS). This phenomenon has gained interest because ultrasound methods are able to quantify the optic nerve sheath diameter (ONSD) in-vivo non-invasively with a resolution below 0.5 mm. In order to study the normal variation and distensibility of the human ONS. Histologic techniques and sonographic measurements were applied to 54 human optic n. specimens before and after exposure to pressure. In untreated postmortem specimens, the largest diameters were found 3 mm behind the globe (baseline range: 2.1 to 4.8 mm). Following volume injection into the orbital perineural SAS, all n. sheaths were enlarged (maximum ONSD 6.5 mm). The sheath expansion affected predominantly its anterior section (mean 1.6 mm, e.g. 50.2%); the posterior regions showed markedly less dilatation (31.6%). No relation was found between the change of ONSD and the baseline diameter. Variance analysis of the sonographic results showed that the observed ONSD change depends on (a) the position of measurement along the nerve, as well as on (b) the origin of the nerve (different/same subject), whereas lateral (left/right) or inter-investigator differences proved negligible. Our results suggest that individual factors determine both baseline sheath diameter and distensibility. The different extent of pressure-induced sheath expansion along the nerve may be partly due to the non-uniform distribution of subarachnoid trabecular fibers between nerve and sheath. In conclusion, measurements of the ONSD for clinical purposes should be targeted to the region immediately behind the globe. Under conditions of raised pressure around the intraorbital optic n., bilateral ONSD measurements should give comparable findings.

Humans↗
PubMed2004

[Optical Rhinometry. Continuous, direct measurement of swelling of the nasal mucosa with allergen provocation. Real-time monitoring of the nasal provocation test using optical rhinometry].

BACKGROUND: Various methods exist for measuring swelling of the nasal mucosa. This is necessary in order to make the nasal provocation test objective. With the new method of optical rhinometry, it is possible to measure swelling of the mucosa directly from outside of the nose in real-time. The measurement is carried out with monochromatic near-infrared light of different wavelengths, the intensity change of which are recorded and displayed during the swelling. MATERIALS AND METHODS: With the help of a specially developed prototype of an optical rhinometer, we carried out measurements on 15 subjects having positive nasal provocation tests with histamine and allergens, negative provocation tests with allergens in non-allergics, negative provocation tests with control solution, and decongestion with xylometazoline. RESULTS: We found significant differences between positive and negative provocation tests ( P<0.01). Decongestion was different from all other groups ( P<0.01). Nasal congestion subjectively reported by the subject always correlated with the optical rhinometry findings. CONCLUSION: The objective assessment of nasal swelling using optical rhinometry seems reliable. The course of the endonasal swelling can thereby be monitored in real-time. The measurement is largely independent of the cooperation of the patient. The swelling is measured directly and not indirectly via air flow resistance.

Diagnosis, Computer-Assisted↗
PubMed1999

Optical PCR: genomic analysis by long-range PCR and optical mapping.

Optical mapping is an approach for the rapid, automated, non-electrophoretic construction of ordered restriction maps of DNA from ensembles of single molecules. Previously, we used optical mapping to make high-resolution maps of large insert clones such as bacterial artificial chromosomes (BAC) and large genomic DNA molecules. Here, we describe a combination of optical mapping and long-range polymerase chain reaction (PCR), in a process we term optical PCR, which enables automated construction of ordered restriction maps of long-range PCR products spanning human genomic loci. Specifically, we amplified three long PCR products, each averaging 14.6 kb in length, which span the 37-kb human tissue plasminogen activator (TPA) gene. PCR products were surface mounted in gridded arrays, and samples were mapped in parallel with either ScaI, XmnI, HpaI, ClaI, or BglII. A contig of overlapping high-resolution maps was generated, which agreed closely with maps predicted from sequence data. The data demonstrate an approach to construct physical maps of genomic loci where very little prior sequence information exists, since the only sequence needed is that required to anchor PCR primers. Large segments of genomic DNA (within the practical limits imposed by long-range PCR) can be mapped quickly and to high resolution without the use of cloning vectors.

DNA Restriction Enzymes↗
PubMed2005

Optical quality changes of the ocular lens during induced parr-to-smolt metamorphosis in Rainbow Trout (Oncorhynchus mykiss). Ocular lens optical quality during induced salmonid metamorphosis.

The effect of an induced salmonid parr-to-smolt metamorphosis ('smoltification') on the optical quality of the ocular lens was studied. In two separate experiments, rainbow trout (Oncorhynchus mykiss) parr were fed thyroxine in their diet to induce the metamorphosis. Lenses were excised at regular samplings during the treatment period and optically scanned using a custom scanning laser monitor. Radioimmunoassay was used to measure serum titers of thyroxine and 3,5,3'-triiodo-L: -thyronine. It was found that lens optical quality was consistently negatively correlated with 3,5,3'-triiodo-L: -thyronine levels, but not with thyroxine levels. To test if thyroid hormones are directly responsible for the change in optical quality, rainbow trout lenses were cultured for 72 h in a medium containing 3,5,3'-triiodo-L: -thyronine, but no effect was observed. The significance of these findings in the contexts of the fishes' visual capabilities and smolting physiology is discussed.

Animals↗
PubMedDate not supplied

Optic disk manifestation in diabetic eyes with low serum albumin: late fluorescein staining and high blood flow velocities in the optic disk.

PURPOSE: To evaluate ocular findings and blood flow characteristics in diabetes mellitus (DM) patients with low serum albumin (ALB). METHODS: We studied 106 eyes of 53 type II DM patients without proliferative diabetic retinopathy and panretinal photocoagulation. All underwent standard ophthalmic examinations, color Doppler imaging, and serum ALB measurements. The patients were divided into Group 1 (34 cases) with a serum ALB > or =3.8 g/dl and Group 2 (19 cases) with ALB<3.8 g/dl. RESULTS: All of the optic disks appeared normal by Ophthalmoscopy except one case with the lowest serum ALB. The number of optic disks showing late fluorescein staining was significantly higher in Group 2 than in Group 1. Peak systolic velocities in the central retinal artery (CRA, P=0.02) and central retinal vein (CRV, P<0.001) were significantly higher in Group 2, and significantly correlated with the serum ALB value (CRA; r=0.41, P=0.003 and CRV; r=0.60, P<0.001). CONCLUSIONS: We suggest that low serum ALB enhances the permeability of the vessels in or around the optic disk and induces subclinical optic disk edema, which is characterized by late fluorescein staining and high blood flow velocities in the CRA and CRV.

Aged↗
PubMed1988

Variability and reproducibility of optic disk topographic measurements with the Rodenstock Optic Nerve Head Analyzer.

Variability of optic disk topographic measurements obtained with the Rodenstock Optic Nerve Head Analyzer was determined by obtaining three separate images on one eye of ten normal subjects and nine subjects without glaucoma. Marking of the disk margin was performed in a random and masked fashion on each image three times by three independent observers. The overall variabilities of the measurements of the subjects with glaucoma were not statistically different from those of the normal subjects. Overall variability was about 0.2 mm2 for total disk area, 0.08 for cup/disk ratio, 0.2 mm2 for disk rim area, and 0.07 mm3 for cup volume. The largest component of the variability was the result of acquisition of separate images of the optic disk at different times. Observer inconsistency in marking the disk edge was relatively small. Based on the expected amount of random variability of the measurements, we proposed criteria for detecting significant change in the optic disk over time.

Adult↗
PubMed1986

Intraocular colchicine inhibits competition between resident and foreign optic axons for functional connections in the doubly innervated goldfish optic tectum.

After unilateral optic tectum ablation in the goldfish, regenerating optic axons grow into the optic layers of the remaining ipsilateral tectal lobe and regain visual function. The terminal arbors of the foreign fibers are initially diffusely distributed among the resident optic axons, but within two months the axon terminals from each retina are seen to segregate into irregular ocular dominance patches. Visual recovery is delayed until after segregation. This suggests that the foreign fibers compete with the residents for tectal targets and that the segregation of axon terminations is an anatomical characteristic of the process. Here we investigate whether inhibiting axonal transport in the resident fibers inhibits competition with foreign fibers. The eye contralateral to the intact tectal lobe received a single injection of 0.1 microgram colchicine, which does not block vision with the intact eye. We measured visual function using a classical conditioning technique. Segregation of axon terminations was examined shortly following visual recovery by autoradiography. The no-drug control fish showed reappearance of vision with the experimental eye at 9 weeks postoperatively and ocular dominance patches were well developed. Colchicine administered to the intact eye (resident fibers) several weeks postsurgery decreased the time to reappearance of vision with the experimental eye by several weeks. Autoradiography revealed some signs of axonal segregation but the labeled foreign axons were mainly continuously distributed. Administration of colchicine at the time of tectum ablation, or of lumicolchicine at two weeks postoperatively produced normal visual recovery times. Fast axonal transport of 3H-labeled protein was inhibited by 1.0 and 0.5 microgram but not by 0.1 microgram of colchicine or by 1.0 microgram of lumicolchicine.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1996

GABA immunopositive axons in the optic nerve and optic tract of macaque monkeys.

Using an antibody to gamma-aminobutyric acid (GABA), we examined the optic nerves and optic tracts from macaque monkeys at the light and electron microscopic levels to determine if there is a possible inhibitory projection from the retina to the brain. All of the monkeys (n = 5) had GABA immunopositive axons that were evenly distributed in their optic nerves. These immunopositive axons were slightly larger than the axons around them and comprised an average of 2.6% of the axons in the nerves. Thus, their estimated total was about 44,000 axons per nerve. In the optic tracts, the GABA immunopositive axons were not distributed evenly, but were concentrated mostly in the ventromedial part, indicating that this retinal pathway probably goes to a midbrain destination such as the superior colliculus. The present findings provide further evidence that there is a GABAergic retinal projection to the brain in primates with currently unknown physiological influences.

Animals↗
PubMed1999

Optical cross-sectional assessment of the macula by retinal thickness analyzer in optic disk pit maculopathy.

PURPOSE: To assess the morphologic changes in optic disk pit maculopathy. METHOD: Case report. A 45-year-old woman with optic disk pit maculopathy in the left eye was examined with the scanning retinal thickness analyzer before and after vitrectomy with intravitreal gas tamponade. RESULTS: Preoperatively, optical cross-sectional retinal thickness analyzer images clearly demonstrated the extent of retinoschisis and outer layer detachment in the macula. Postoperatively, the retinal thickness analyzer images showed that retinal thickening decreased as the intraretinal fluid in the schisis cavity was absorbed and then gradually decreased further as the outer layer detachment in the fovea resolved. CONCLUSIONS: Scanning retinal thickness analyzer can be used to diagnose and monitor the structural changes of the macula lesion in optic disk pit maculopathy. Vitrectomy with gas tamponade may be effective for treating this disease.

Diagnostic Techniques, Ophthalmological↗
PubMed1999

Topographic analysis to discriminate glaucomatous from normal optic nerve heads with a confocal scanning laser: new optic disk analysis without any observer input.

PURPOSE: We evaluated the potential ability of a confocal scanning laser ophthalmoscope to differentiate patients with normal visual fields from those with abnormal visual fields with an optic nerve head topographic map. PATIENTS AND METHODS: Twenty normal eyes with normal visual fields, intraocular pressures of less than 22 mm Hg, and no family history of glaucoma and 20 glaucomatous eyes with abnormal visual fields and open angles were selected. Glaucomatous eyes with advanced visual field damage were not included. One eye was chosen randomly from each patient. All eyes were examined with the Heidelberg Retina Tomograph (HRT [Heidelberg Engineering GMBH, Heidelberg, Germany]) and Humphrey Perimeter, program 30-2 (Humphrey Instruments, Inc., San Leandro, CA, USA). Topographic maps were analyzed with different methods based on contour lines, with use of a program able to differentiate glaucomatous from normal optic disks. Sensitivity, specificity, and diagnostic precision were calculated. RESULTS: The analysis had a sensitivity, specificity, and diagnostic precision of 80%, 100%, and 90%, respectively. CONCLUSION: With the topographic map data and this technique, the HRT's capacity to differentiate normal optic disks from glaucomatous disks was improved. In addition, with this method, we avoided any subjective observer input in drawing the optic nerve head outline.

Aged↗
PubMed2000

Optical correction of form deprivation myopia inhibits refractive recovery in chick eyes with intact or sectioned optic nerves.

The finding that the eyes of young chicks recover quickly from form deprivation myopia (FDM) has been interpreted as indirect evidence for active emmetropization. More direct evidence would be the demonstration that correction of FDM with spectacle lenses, thereby removing the defocus signal, prevents recovery. We investigated this issue in eyes with intact and sectioned (ONS) optic nerves. Previous studies suggest that an intact optic nerve is necessary for accurate emmetropization. Seventy day-old male chicks were monocularly deprived using velcro-mounted diffusers, which were removed after 5-6 days and in some (n=51), but not all cases, replaced by spectacle lenses (-5, -10 or -15 D). Approximately half (n=34) of the chicks also underwent ONS on day 1. Refractive errors and axial ocular dimensions were measured when the diffusers were first removed and thereafter at 2-4 day intervals over the following 1-2 weeks. In one case, measurements were continued at less regular intervals to 33 days. Lens powers were selected to either approximately correct or under-correct the refractive errors present when the diffusers were removed. Form deprivation in normal chicks produced large myopic shifts in refraction (means for groups range from -9.20 to -16.07 D). When the deprivation treatment was terminated, the myopia quickly decreased to negligible levels unless optically corrected. Correcting lenses stabilized the myopia to a level consistent with the lens power used. Interocular differences in axial length were consistent with an axial origin to the refractive changes. Results for the ONS groups exhibited similar trends although there was increased variability in the data. The findings support the interpretation that recovery from FDM is a product of active emmetropization. That ONS increased the variability of such responses implies that an intact optic nerve is required for accurate emmetropization.

Animals↗
PubMed1997

NMDAR1-like immunoreactive fibers appear in the ipsilateral optic tract during optic nerve regeneration in Rana pipiens.

N-Methyl-D-aspartate receptor subunit 1-like immunoreactivity (NMDAR1-LI) was investigated in the brain of Rana pipiens during optic nerve regeneration. Following unilateral optic-nerve crush, frogs were tested for prey-catching and optokinetic nystagmus responses to assess return of visual function. At 1, 2, 3 and 5 months after the surgery, NMDAR1-LI was assessed in central visual pathways. At 3 and 5 months, conspicuous ipsilateral NMDAR1-LI fibers were detected in the thalamic and pretectal nuclei, and the time of their appearance coincided with the onset of behavioral recovery. Also, only ipsilateral retinorecipient layers in the optic tectum showed increased NMDAR1-LI during optic nerve regeneration. These results suggest that NMDA receptors may be present on retinal ganglion cell axons and terminals that have been misrouted during regeneration.

Animals↗