摘要:

The effect of electrical stimulation of the sympathetic nerves on the blood-aqueous barrier was investigated in rabbits. The permeability of the barrier was assessed during either acute, chronic or following chronic nerve stimulation. During acute and chronic stimulation of the sympathetic nerves, fluorescein entered the anterior chamber at a rate significantly slower than in control eyes. After chronic stimulation, both the rate of entry of fluorescein and the aqueous humor protein concentration were much greater than in control eyes indicating breakdown of the blood-aqueous barrier. Treatment with the non-steroidal anti-inflammatory drugs, indomethacin and suprofen, completely blocked the breakdown of the blood-aqueous barrier. These results indicate that sympathetic nerve stimulation can cause the local synthesis of prostaglandins and that these can affect the blood-aqueous barrier.

ISSN:0271-3683    

DOI:10.3109/02713689009069929

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

In an earlier study we reported large discrepancies between ocular refraction and perception of blur for black/white letters. In the present study we report on the influence of target color and vergence of light on the human focusing system. Twenty visually normal volunteers between 14 and 25 years of age participated in this experiment. Targets were brightness-matched red, yellow, green, blue or white 21 minarc letters displayed on the black background of a high resolution RGB monitor, at a 40 cm observation distance. Changes in the vergence of light were effected via increasing amounts of positive and negative power spherical lenses placed binocularly in front of the subject's eyes. Our results showed that: 1) the accommodative level varied as a function of the color of a target, 2) the vergence of light was not an infallible cue for accurate accommodation and 3) the inter-subject variability seen in response to the vergence of light was not linked with the chromaticity of test targets. All subjects showed a decreasing ability to fully relax accommodation with increasing plus power lenses. For minus power lenses, accommodative response profiles were divided into 3 categories, category 1 having accurate accommodation for the test target, category 2 showing a low level lag of accommodation and category 3 being totally unresponsive to increasing divergence of light. While subjects across response categories showed differential endpoints in clinical estimates of positive relative accommodation, other clinical measurements related to refractive error, accommodative amplitude and fusional ability failed to predict the accommodative behavior of our subjects as did measurements of the resting focus of accommodation.

ISSN:0271-3683    

DOI:10.3109/02713689009069930

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

Recently, we reported the partial characterization of bovine lens intrinsic membrane proteins having apparent SDS-PAGE derived molecular mass of 19, 21, and 23 kDa, and determined that they contained identical NH2-terminal amino acids. sequences for the first 20 amino acids. From this amino acid sequence information, a mixed synthetic oligonucleotide was constructed and used to screen a calf lens lambda gt11 cDNA library in order to isolate and characterize the cDNA coding for this membrane polypeptide(s). Two separate cDNA clones were isolated and sequenced, and were found to have an identical sequence of 883 bases with an open reading frame coding for a polypeptide of 173 amino acids, having a molecular mass of 19,683 Daltons. The first 20 amino acids of the translated sequence were identical to that determined by our laboratory previously, and the last seven amino acids were identical to that recently determined by another laboratory from analysis of the extracted polypeptides, indicating that this cDNA is the authentic molecule coding for MP19.

ISSN:0271-3683    

DOI:10.3109/02713689009069931

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

The transforming growth factor-βs are peptide growth factors known to play a central role in wound healing. Using a specific, in vitro assay of cell growth inhibition, we have detected transforming growth factor-β(TGF-β) in 24/24 aqueous humor specimens from eyes undergoing cataract extraction with intraocular lens implantation. The amount of TGF-βranged from 2.3 to 8.1 ng/ml (mean±SD = 4.5±1.7 ng/ml), with 61% present in the active form.Subtyping of TGF-βwas performed by addition of antibodies specific for theß1 andß2 isoforms to the growth inhibition assay, and confirmed with a sandwich enzyme-linked immunosorbent assay. None of the TGF-βdetected was of theß1 isoform; in contrast, theß2 isoform was present in every sample, implying that it might have originated from ocular tissues. The presence of this potent modulator of tissue repair in aqueous humor suggests a role in the healing processes following intraocular surgery, including glaucoma filtration surgery.

ISSN:0271-3683    

DOI:10.3109/02713689009069932

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

Rapid and continuous fluctuations in ocular focus are known to occur when the eye views a stationary target. The advent of high-speed infra-red optometers has established that these microfluctuations of ocular accommodation have two dominant components: low frequency of<0.6 Hz and high frequency between 1.0-2.3Hz. Although the retinal image blur associated with microfluctuations has the potential to guide and maintain optimum accommodation levels, there is no consensus with regard to the respective contribution of each of the dominant frequency components. Using a newly-designed measurement and recording system we show that, when viewing a stationary target located at 25cm, individuals exhibit little variation in the frequency of low frequency components but significant variation in high frequency components. Simultaneous measurements of ocular accommodation and systemic arterial pulse demonstrate that the variation in high frequency component is significantly correlated with arterial pulse frequency. Since control experiments indicate that the microfluctuations are derived from activity of the crystalline lens our observations could provide the basis for a non-invasive method of assessing the effects of arterial pulse on ciliary body/choroidal vasculature, the vitreous/lens interface and intraocular pressure. Further, it is feasible that under certain conditions an abnormal increase in the magnitude of arterial pulse may affect the aggregate nature of accommodative microfluctuations to an extent that disrupts the normal control processes maintaining optimum retinal contrast during sustained near vision.

ISSN:0271-3683    

DOI:10.3109/02713689009069933

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

The major high molecular weight, fucose containing, cell surface glycoproteins of cultured rat retinal pigment epithelial (RPE) cells were partially characterized. One dimensional peptide mapping by the Cleveland method showed that the polypeptide chains of these proteins were not highly related in structure. Incorporation of3H-mannose into these glycoproteins was equivalent for normal and dystrophic (RCS rdy p+) RPE. Furthermore, treatment of the glycoproteins from either normal or dystrophic RPE with Endo-β-N-acetylglucosaminidase H (Endo H) did not cause a shift in their Mr's, as determined by SDS PAGE. These results suggest that the high Mrglycoproteins do not contain a large quantity of unprocessed, mannose containing core type N-linked oligosaccharides in either normal or dystrophic RPE. Digestion of the3H-fucose labeled glycoproteins with Peptide N-glycosidase F (PNGase F) demonstrated that at least 90% of the3H-fucose incorporated into these glycoproteins is in N-linked oligosaccharides. Endo-β-N-acetylglucosaminidase F (Endo F) treatment showed that at least 75-80% of the3H-fucose is located in more terminal positions (distal to the fucose that is found inα1,6 linkage to the asparagine-linked N-acetylglucosamine residue) in N-linked carbohydrate. Overall, these results support the hypothesis that if the dystrophic RPE possesses a defect in glycoprotein processing, then this defect affects terminal processing of oligosaccharides and addition of terminally located fucose residues. A homologous group of high Mr, fucosylated glycoproteins was found in plasma membranes from cultured monkey RPE, suggesting that they may be common to other species.

ISSN:0271-3683    

DOI:10.3109/02713689009069934

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

Purified bovine rod outer segments (ROS) were used to study the transfer of labeled galactose from UDP-[3H]galactose to endogenous ROS glycoproteins, exogenous glycoproteins and N-acetylglucosamine (GlcNAc). The ROS reaction was also compared with that of the retinal microsomal fraction and milk galactosyltransferase. The results indicate that the ROS reaction was enhanced by exposure to light. Illumination, however, had no effect on the transfer of labeled galactose to either endogenous microsomal glycoproteins by retinal microsomal galactosyltransferase or the transfer of the sugar to ROS glycoproteins by milk galactosyltransferase. Manganese was most effective, followed by cobalt, as cofactor for the ROS enzyme. Calcium and magnesium produced about 60% of the activity observed with manganese. The ROS enzyme transferred minimal amounts of labeled galactose to asialo-agalacto-transferrin or ovalbumin but readily transferred the sugar to GlcNAc. The latter reaction had an optimum pH of 6.3 and was linear for at least 90 min. It reached a maximum at about 30 mM GlcNAc and was inhibited by higher concentrations of the aminosugar and by low concentrations ofα-lactalbumin. On the other hand, the transfer of galactose to ROS glycoproteins was not affected by low concentrations ofα-lactalbumin. Our data suggest that the ROS galactosyltransferase may have a certain specificity towards its acceptor in the ROS. Its activation by light may indicate a role in the light-activated processes of the photoreceptor cell.

ISSN:0271-3683    

DOI:10.3109/02713689009069935

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

Tears from normal (n=5) and serum IgA deficient (n=3) individuals were investigated for the presence of secretory Immunoglobulin A (sIgA), sIgM and free secretory component (SC) by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) using 10-15% gradient minigels (PhastSystem), followed by immunoblotting using various immunological probes. Tear samples were treated in denaturing (SDS) sample buffer under non-reducing as well as reducing conditions, prior to analysis.All normal tear samples contained sIgA as well as free SC (estimated MW: 82kD) but only traces of IgM. Tears from the three serum IgA deficient subjects lacked sIgA but did contain free SC. In two of them sIgM was clearly detected and after treatment of tears with reducing agent, IgM (µ) heavy chain fragments (estimated MW: 78kD) were identified and could be distinguished from other tear proteins after SDS-PAGE.These findings indicate lacrimal secretion of free secretory component, even in the absence of its ligand. On the ocular surface, sIgM may play a compensatory role in IgA deficiency.

ISSN:0271-3683    

DOI:10.3109/02713689009069936

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

Previous studies demonstrated that non-specific beta blockade promoted ocular shedding of latent HSV-1 in the mouse and rabbit iontophoresis models. The present study examined the effect of topical alpha blockers, thymoxamine and corynanthine, on reactivation and induced ocular shedding of latent HSV-1 W in different host animals. Latent trigeminal ganglionic infection was established in Balb/c mice and New Zealand rabbits following corneal inoculation with HSV-1 W strain, and later confirmed by co-cultivation. Treatment with coded eye drops (thymoxamine, corynanthine or BSS was begun one day prior to iontophoresis induction and continued BID OU for 5 days. Reactivation and recovery of latent HSV-1 was determined by daily ocular swabs, and characteristic HSV-1 cytopathic effect in Vero cells. In Balb/c mice, topical administration of thymoxamine 0.5% or corynanthine 5% significantly reduced the number of virus-positive eyes, virus-positive mice, and total virus-positive swabs per experiment, whereas the inhibitory effect was minimal in NZ rabbits. We conclude that alpha blockade may alter the reactivation signal that is mediated via the adrenergic system, and that different host factors (as expressed in different species) may play an important role in this process.

ISSN:0271-3683    

DOI:10.3109/02713689009069937

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

Vanadate is a potent inhibitor of calcium stimulated ATPase, Na, K-ATPase, and may have adrenergic activity. Using the iontophoresis method, we compared vanadate to a BSS control and the standard iontophoresis model (6-hydroxydopamine/epinephrine) by measuring induced ocular shedding of latent HSV-1 in different host animals. Latent trigeminal ganglionic infections were established in Balb/c mice and New Zealand rabbits following corneal inoculation with HSV-1 [W] strain, and later confirmed by cocultivation. Latently-infected animals (>1 month post-infection) were divided into three treatment groups. Each group was iontophoresed with BSS, vanadate 1% or 6-HD 1%, and then treated topically for 10 days with BSS, vanadate or epinephrine respectively. Reactivation and recovery of latent HSV-1 was detected by daily ocular swabbing, plating, and observing progressive viral growth in Vero cells. The vanadate group had more virus-positive eyes than the BSS control group in mice, (8/32 vs. 1/32 P<.01), and also in rabbits (14/20 vs 6/22 P<.01). Virus-positive animals and total positive swabs were also higher for vanadate than BSS in both mice and rabbits. Furthermore, while vanadate was associated with fewer virus-positive eyes than 6-HD&EPI (8/32 vs. 17/32 P<.02) in mice, there were no significant differences in rabbits. We conclude that vanadate promotes ocular shedding of latent HSV-1, and may act through an adrenergic mechanism.

ISSN:0271-3683    

DOI:10.3109/02713689009069938

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor