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At least 343 records · Page 19Linked to original sources
PubMed2006

Optical vibrocardiography: a novel tool for the optical monitoring of cardiac activity.

We present an optical non-contact method for heart beat monitoring, based on the measurement of chest wall movements induced by the pumping action of the heart, which is eligible as a surrogate of electrocardiogram (ECG) in assessing both cardiac rate and heart rate variability (HRV). The method is based on the optical recording of the movements of the chest wall by means of laser Doppler interferometry. To this aim, the ECG signal and the velocity of vibration of the chest wall, named optical vibrocardiography (VCG), were simultaneously recorded on 10 subjects. The time series built from the sequences of consecutive R waves (on ECG) and vibrocardiographic (VV) intervals were compared in terms of heart rate (HR). To evaluate the ability of VCG signals as quantitative marker of the autonomic activity, HRV descriptors were also calculated on both ECG and VCG time series. HR and HRV indices obtained from the proposed method agreed with the rate derived from ECG recordings (mean percent difference <3.1%). Our comparison concludes that optical VCG provides a reliable assessment of HR and HRV analysis, with no statistical differences in term of gender are present. Optical VCG appears promising as non-contact method to monitor the cardiac activity under specific conditions, e.g., in magnetic resonance environment, or to reduce exposure risks to workers subjected to hazardous conditions. The technique may be used also to monitor subjects, e.g., severely burned, for which contact with the skin needs to be minimized.

Adult↗
PubMed1986

The optic tectum regulates the transport of specific proteins in regenerating optic fibers of goldfish.

The pattern of rapidly-transported proteins in regenerating optic fibers of the adult goldfish is regulated by interactions between these fibers and their main target, the optic tectum. When the optic fibers are allowed to interact with the tectum, the transport of proteins with molecular weights in the range of 110-145 kilodaltons (kDa) increases, whereas the transport of proteins in the 24-27 kDa range declines from the previously high level which has been induced by axotomy. If the optic fibers are prevented from interacting with the tectum, the transport of the 24-27 kDa proteins remains elevated for months. Amounts of other rapidly-transported retinal proteins (e.g. the acidic 43-49 kDa proteins that increase in regenerating optic fibers after axotomy) are relatively unaffected by tectal ablation.

Animals↗
PubMed1990

Effect of optic nerve lesions and intraocular colchicine on cell proliferation in the germinal zone of the optic tectum and in the torus longitudinalis in the goldfish.

Postembryonic development of the optic tectum occurs in part through proliferation of cells in the germinal zone located at the caudal edges of each lobe. Autoradiography experiments by others have shown that [3H]thymidine labeling in the germinal zone is decreased following optic nerve crush or enucleation and restored above normal levels during optic nerve regeneration. The present autoradiography experiments examined the relationship between retinal innervation and the rate of mitotic activity in the tectum germinal zone and in the torus longitudinalis. The fish received optic nerve crush to temporarily deafferent the tectum, enucleation for permanent deafferentation, or an intraocular injection of 0.01-1.0 microgram of colchicine to reversibly inhibit axonal transport in the optic nerve. Thymidine labeling in the tectum germinal zone showed that nerve crush resulted in decreased mitotic activity in most fish within 6 days followed by recovery by 21 days; enucleation decreased mitotic activity more uniformly and for more than 42 days with recovery by 84 days postaxotomy; colchicine produced a dose-dependent inhibition of mitotic activity which was reversed by 42 days postinjection. Axonal transport was restored by 42 days postinjection. In the torus longitudinalis, nerve crush produced a brief increase in mitotic activity followed by a return to normal; enucleation and colchicine resulted in a lasting decrease in mitotic activity and atrophy indicating a loss of cells or neuropil. The data are consistent with the proposal that cell proliferation in the tectum germinal zone is stimulated by the accretion of fibers from developing retinal ganglion cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Effect of optic nerve transection on N-acetylaspartylglutamate immunoreactivity in the primary and accessory optic projection systems in the rat.

Evidence has been presented in recent years that support the hypothesis that N-acetylaspartylglutamate (NAAG) may be involved in synaptic transmission in the optic tract of mammals. Using a modified fixation protocol, we have determined the detailed distribution of NAAG immunoreactivity (NAAG-IR) in retinal ganglion cells and optic projections of the rat. Following optic nerve transection, dramatic losses of NAAG-IR were observed in the neuropil of all retinal target zones including the lateral geniculate nucleus, superior colliculus, nucleus of the optic tract, the dorsal and medial terminal nuclei and suprachiasmatic nucleus. Brain regions were microdissected and NAAG levels measured by a radioimmunoassay (RIA) (IC50: NAAG = 2.5 nM, NAA = 100 microM; smallest detectable amount = 1-2 pg/assay). Large decreases (50-60%) in NAAG levels were detected in the lateral geniculate, superior colliculus and suprachiasmatic nucleus. Moderate losses (25-45%) were noted in the pretectal nucleus and the nucleus of the optic tract. Smaller changes (15-20%) were detected in the paraventricular nucleus and the pretectal area. These results are consistent with a synaptic communication role for NAAG in the visual system.

Animals↗
PubMed1996

Optic nerve glioma mimicking an optic nerve meningioma.

The case is described of an optic nerve glioma, mimicking an optic nerve meningioma in a man aged 41 years. CT, MRI and DSA revealed an enhancing tumor surrounding the optic nerve. Histopathologic examination of the removed optic nerve revealed a centrally located glioma surrounded by normal optic nerve fibres.

Adult↗
PubMed1981

Enzyme histochemical changes in some optic projection areas of the goldfish after optic nerve lesions.

Enzyme histological changes have been studied in several optic projection areas after right optic nerve lesion in goldfish. An increase in acid phosphatase activity was found in the optic tectum, nucleus rotundus, nucleus geniculatus lateralis and area pretectalis between 2 and 15 days postoperatively. The enzymes glutamate dehydrogenase, lactate dehydrogenase, NADH tetrazolium reductase, cytochrome oxidase, succinate dehydrogenase and beta-hydroxybutyrate dehydrogenase showed a decrease in activity in all or some of these projection areas. No changes were found in acetylcholinesterase activity after optic nerve lesions. Three weeks postoperatively, all enzyme activities returned to the same level as on the normal side. The results are discussed in relation to possible neurotransmitters in goldfish optic terminals.

Acid Phosphatase↗
PubMed2001

Magnetization transfer and diffusion tensor MR imaging of the optic radiations and calcarine cortex from patients with Leber's hereditary optic neuropathy.

Optic nerve abnormalities are easily detectable in patients with Leber's hereditary optic neuropathy (LHON), using magnetic resonance imaging (MRI). However, the presence of structural changes in the optic radiations and calcarine cortex of these patients is still an unresolved issue. In this study, we obtained magnetization transfer (MT) and diffusion tensor (DT) MRI to investigate the integrity of these structures in patients with LHON. Dual echo, MT- and DT-MRI scans of the brain were obtained from 10 men with LHON and 10 healthy sex- and age-matched controls. After image co-registration, we obtained MT ratio (MTR), average diffusivity (D) and fractional anisotropy (FA) maps. MTR, D and FA values for the white matter of the optic radiations and MTR and D values for the calcarine cortex were obtained using a region of interest (ROI) analysis. No macroscopic abnormalities were detected in any of the scans from LHON patients and controls. No statistically significant differences of MTR, D or FA values were found for any of the regions studied in LHON patients and healthy controls. Our results suggest that, in patients with LHON, the optic radiations and the calcarine cortex are spared from structural damage, both at a macroscopic and a microscopic level.

Adult↗
PubMed1991

Correlation between amount of retinal afferents to the pretectal nucleus of the optic tract and dorsal terminal accessory optic nucleus and performance of horizontal optokinetic reflex in rat.

Intraocular kainic acid injection in Long-Evans rats induces loss of retinal afferents to subcortical visual centers as assessed by the axoplasmic transport of [14C]valine. The optical terminal fields of the pretectal nucleus of the optic tract (NOT), superior colliculus and accessory optic system (AOS) nuclei appear particularly affected. Since NOT and the AOS dorsal terminal nucleus (DTN) represent the first relay station of the visuomotor pathway mediating horizontal optokinetic nystagmus (HOKR), we have studied the characteristics of HOKR after various degrees of retinal deafferentation of these nuclei induced by intraocular KA injection. Taking advantage of the arrangement of the primary optic projections to NOT-DTN, that in rats are almost entirely crossed, in each animal, monocular HOKR induced by stimulation of the injected eye was compared to monocular HOKR elicited by stimulation of the intact, ipsilateral eye. Following NOT-DTN optic denervation, HOKR gain always worsened, and in a way, that the greater the deficits of retinal afferents, the greater the HOKR inability to compensate for visual motion. Furthermore, for any given retinal denervation the higher the stimulus velocity, the greater the HOKR deficit. While the correlation between HOKR gain and the amount of retinal afferents to NOT-DTN would seem to indicate a functional homogeneity of the retinal ganglion cells sending axons to these nuclei, the finding that the extent of HOKR impairment also varied with velocity might not support the above view.

Animals↗
PubMed2000

The influence of age, gender, refractive error, and optic disc size on the optic disc configuration in Japanese normal eyes.

PURPOSE: To investigate the influence of age, gender, refractive error, and optic disc size on optic disc configuration in Japanese normal eyes. METHODS: Ninety-two eyes from 92 visually normal Japanese subjects (mean refractive error+/-SD: -1.26+/-2.25 D, range -8 D to +3 D) were examined using a confocal scanning laser tomograph, TopSS. The following disc parameters were investigated: disc size, total or quadrant C/D area ratio and neuroretinal rim area, half-depth area, volume below, and average cup depth. RESULTS: The disc diameter ( mean+/-SD: 1.84+/-0.16 mm) and disc size showed highly significant correlations with the C/D ratio (p<0.001) and the neuroretinal rim area (p<0.001). No other correlation was observed. CONCLUSION: These results indicate that the optic disc diameter and disc size have higher correlations with the optic disc configuration than age, gender, and refractive error in Japanese. These results are similar to those data reported for eyes of Caucasians or Afro Americans, and should be considered when optic discs are evaluated.

Adult↗
PubMed2000

[Monitoring of morphometric changes of optic discs with morphologic progression of glaucomatous optic atrophy by means of laser scanner tomography].

AIM: Aim of this study was to measure morphometric changes in optic discs with laser-scanning tomography (HRT, Heidelberg-Retina-Tomograph, Heidelberg) in eyes with early glaucomatous morphologic progression. PATIENTS AND METHODS: 61 eyes of 36 patients with marked neuroretinal rim loss or its early morphologic signs (1. optic disc hemorrhages, 2. reduced visibility of the retinal nerve fiber layer (RNF), 3. appearance of narrowing of retinal vessels, 4. enlargement of the choroidal, parapapillary atrophy) were compared to 74 normal eyes of 39 probands. 15 degrees stereographs of the optic discs were evaluated for morphologic changes. The morphometric variables of the neuroretinal rim and excavation measured by the HRT were examined in the course of the disease. RESULTS: In the group of normals no significant changes of the neuroretinal rim in the course of 2.0 +/- 1.2 years were found. In the group of glaucomatous eyes (3.0 +/- 1.5 years follow-up) 34 eyes showed marked neuroretinal rim loss, 17 disc hemorrhages, 4 vessel narrowing, 3 an increased chorioidal atrophy, 3 a decreased visibility of the retinal nerve fiber layer. In these eyes a significant loss of rim area (p = 0.01) and an increase of excavation area (p = 0.0001) and volume (p = 0.003) was measured by the HRT. Only three eyes showed a perimetric loss of sensitivity (0.8-3.4 db) in Octopus static perimetry. CONCLUSIONS: Laser-scanning tomography of the optic disc seems to be able to measure morphometric changes in eyes with morphologic progression of glaucomatous optic atrophy, even before perimetric changes occur.

Adult↗
PubMed1992

A randomized, controlled trial of corticosteroids in the treatment of acute optic neuritis. The Optic Neuritis Study Group.

BACKGROUND AND METHODS: The use of corticosteroids to treat optic neuritis is controversial. At 15 clinical centers, we randomly assigned 457 patients with acute optic neuritis to receive oral prednisone (1 mg per kilogram of body weight per day) for 14 days; intravenous methylprednisolone (1 g per day) for 3 days, followed by oral prednisone (1 mg per kilogram per day) for 11 days; or oral placebo for 14 days. Visual function was assessed over a six-month follow-up period. RESULTS: Visual function recovered faster in the group receiving intravenous methylprednisolone than in the placebo group; this was particularly true for the reversal of visual-field defects (P = 0.0001). Although the differences between the groups decreased with time, at six months the group that received intravenous methylprednisolone still had slightly better visual fields (P = 0.054), contrast sensitivity (P = 0.026), and color vision (P = 0.033) but not better visual acuity (P = 0.66). The outcome in the oral-prednisone group did not differ from that in the placebo group. In addition, the rate of new episodes of optic neuritis in either eye was higher in the group receiving oral prednisone, but not the group receiving intravenous methylprednisolone, than in the placebo group (relative risk for oral prednisone vs. placebo, 1.79; 95 percent confidence interval, 1.08 to 2.95). CONCLUSIONS: Intravenous methylprednisolone followed by oral prednisone speeds the recovery of visual loss due to optic neuritis and results in slightly better vision at six months. Oral prednisone alone, as prescribed in this study, is an ineffective treatment and increases the risk of new episodes of optic neuritis.

Acute Disease↗
PubMed1986

Decompression of the optic nerve in the optic canal. A transorbital approach.

Blindness can result from pressure on the optic nerve in the optic canal, either from trauma or from neoplasm. The usefulness, timing, and technique of surgical decompression of the optic canal remains controversial. The present paper describes eight patients with optic nerve compression, who had the optic nerve decompressed through a transorbital approach. Because this technique is technically simple and is associated with a low morbidity, it offers a treatment alternative to this difficult group of patients.

Adolescent↗
PubMed2004

Realizability of optical systems of given linear optical character.

The linear optical character of an optical system is represented by a particular type of 5 x 5 matrix. This article shows that the converse is also true, namely, that an optical system can be constructed in principle with linear optical character represented by any matrix of this type. In other words, every matrix of this type is realizable as an optical system. The system may have astigmatic and decentered elements.

Linear Models↗
PubMed2005

Intraobserver and interobserver reliability indices for drawing scanning laser ophthalmoscope optic disc contour lines with and without the aid of optic disc photographs.

PURPOSE: To investigate the effects on topographic optic disc analysis of defining regions of interest (ROIs) by drawing contour lines with and without photographic aid. PATIENTS AND METHODS: Forty-five patients had optic disc imaging by stereoscopic photography and confocal scanning laser ophthalmoscopy using the Heidelberg Retinal Tomograph (HRT). Two experienced observers defined ROIs with a stereoscopic optic disc photograph, with a non-stereoscopic photograph and without any photographic guide. Intraclass coefficients and 95% tolerance limits for change were calculated for each HRT optic disc parameter for the following situations: (1) Intraobserver reliability for ROIs defined with non-stereoscopic photographs and no photograph compared against ROIs defined using stereoscopic photographs; (2) interobserver reliability for ROIs defined without the aid of a photograph, with stereoscopic photographs and with non-stereoscopic photographs; and (3) intraobserver reliability for ROIs defined twice for 23 patients using non-stereoscopic photographs. RESULTS: Intraclass correlation coefficients ranged from 0.63 to 1.00 (ie, 'substantial' to 'perfect' agreement). The 95% tolerance limits for change ranged from 3% to 34%. In general, intraobserver reliability indices were higher than interobserver reliability indices but no method of ROI definition appeared superior. The least reliable measurements were for rim area, rim volume, and disc area. CONCLUSIONS: Non-stereoscopic optic disc photographs are an acceptable alternative to stereoscopic photographs when defining ROIs for HRT analysis. Observers with impaired stereopsis may be able to define reliable ROIs. For HRT algorithms designed to determine a 'diagnosis' of glaucoma, rim area, rim volume, and disc area data should be used with caution.

Adult↗
PubMed1977

The optic disc in glaucoma II: correlation of the appearance of the optic disc with the visual field.

Examination of stereoscopic optic disc photographs allowed accurate prediction of glaucomatous and normal fields to be made in 82 and 95% of eyes respectively and for visual field loss to be correctly located in upper and lower half in 83 and 91% of cases respectively. Despite this high correlation the existence of false positive and fale negative predictions means that the total reliance on optic nerve examination without visual field estimation in the evaluation of the glaucoma patient should not be made. Optic disc examination is too insensitive for long-term follow-up of visual function in a glaucoma patient. The high correlation between the state of the visual field and the optic disc means that, in the evaluation of the visual functions of a glaucoma patient, the appearance of the optic disc and the visual field should be in agreement.

Glaucoma↗
PubMed2005

Optical biopsy of lymph node morphology using optical coherence tomography.

Optical diagnostic imaging techniques are increasingly being used in the clinical environment, allowing for improved screening and diagnosis while minimizing the number of invasive procedures. Diffuse optical tomography, for example, is capable of whole-breast imaging and is being developed as an alternative to traditional X-ray mammography. While this may eventually be a very effective screening method, other optical techniques are better suited for imaging on the cellular and molecular scale. Optical Coherence Tomography (OCT), for instance, is capable of high-resolution cross-sectional imaging of tissue morphology. In a manner analogous to ultrasound imaging except using optics, pulses of near-infrared light are sent into the tissue while coherence-gated reflections are measured interferometrically to form a cross-sectional image of tissue. In this paper we apply OCT techniques for the high-resolution three-dimensional visualization of lymph node morphology. We present the first reported OCT images showing detailed morphological structure and corresponding histological features of lymph nodes from a carcinogen-induced rat mammary tumor model, as well as from a human lymph node containing late stage metastatic disease. The results illustrate the potential for OCT to visualize detailed lymph node structures on the scale of micrometastases and the potential for the detection of metastatic nodal disease intraoperatively.

Animals↗
PubMed2003

Preparation of optically active threo-2-amino-3-hydroxy-3-phenylpropanoic acid (threo-beta-phenylserine) via optical resolution.

To obtain optically active threo-2-amino-3-hydroxy-3-phenylpropanoic acid (1), (2RS,3SR)-2-benzoylamino-3-hydroxy-3-phenylpropanoic acid [(2RS,3SR)-2] was first optically resolved using (1S,2S)- and (1R,2R)-2-amino-1-(4-nitrophenyl)-1,3-propanediol as the resolving agents to afford (2R,3S)- and (2S,3R)-2 in yields of 73% and 66%, based on half of the starting amount of (2RS,3SR)-2. Next, the racemic structures of ammonium and some organic ammonium salts of (2RS,3SR)-2 were examined based on melting point, solubility, and infrared spectrum, with the aim of optical resolution by preferential crystallization. The benzylammonium salt of (2RS,3SR)-2 was suggested to exist as a conglomerate at room temperature, although it forms a racemic compound at the melting point. The optical resolution by preferential crystallization of the racemic salt afforded the (2R,3S)- and (2S,3R)-salts with optical purities of 90-97%. The (2R,3S)- and (2S,3R)-2 obtained from the purified salts were hydrolyzed by reflux in hydrochloric acid to give (2R,3S)- and (2S,3R)-1.

Crystallization↗
PubMed2000

Septo-optic dysplasia with unilateral optic nerve hypoplasia: case report.

Septo-optic dysplasia (de Morsier syndrome) is a well-described entity that includes optic nerve hypoplasia and the absence of the septum pellucidum with or without pituitary abnormalities. We describe a case with unilateral optic nerve hypoplasia and absence of a septum pellucidum. A 6-year-old boy was referred to our clinic because of poor visual acuity. His best-corrected visual acuity was counting fingers at 15 cm in the right eye and 1.0 in the left eye. Extraocular muscle movements were normal, and exotropia of 30 prism diopters by Hirschberg test in the right eye was present. The pupils were equal and reactive to light with a mild Marcus Gunn pupillary response in the right eye. Perimetry revealed small visual fields in the superior quadrants of the right eye, while the left eye was normal. Ophthalmoscopic examination showed a small pale optic disc in the right eye; the optic disc of the left eye was normal. Magnetic resonance imaging showed the absence of the septum pellucidum. Endocrine studies revealed no evidence of pituitary insufficiency.

Child↗