摘要:

Rearing neonatal rats in hyperoxia induces the development of retinal hemorrhages and retinal dysplasia. Albino rats were placed in 80% oxygen immediately after birth and were exposed for either 5, 10, or 14 days, followed by sacrifice or exposure to normoxia for an additional 2, 4, 5, 7, 8, 10, 38, 45 or 56 days. Control rats were simultaneously raised in room air and sacrificed at the same times. All animals were enucleated and their eyes processed for light and electron microscopy. Eyecups were trimmed to facilitate cross-sectioning of the retina in the vertical meridian. No control rats showed signs of retinal hemorrhages or of dysplastic folds or rosettes. Nor did the retinas of rats killed immediately after oxygen exposure contain hemorrhages, but the incidence of retinal folds or rosettes in this group was 54%. For rats exposed to combinations of hyperoxia and brief normoxia (10 days or less), 40% suffered hemorrhages and 50% developed retinal folds or rosettes. Although hemorrhages were more prominent in rats subjected to longer periods of oxygen (73% of all rats exposed for 14 days followed by brief normoxia vs. 6% of those exposed for 5 days followed by brief normoxia), the incidence decreased with time post-exposure in room air. Hemorrhages occurred in 100% of the rats raised in oxygen for 14 days followed by 2 days in room air, and decreased to 50% by 7 days in room air and to 0% by 38 days, indicating a spontaneous resolution with time. In each case, the blood appeared to leak from the newly-forming vessels of the deep capillary net, with most of the red blood cells migrating to the subretinal space. Retinal fold or rosette formation, indicative of developmental dysplasia, occurred in a fraction of virtually all groups of exposed rats, and persisted at the longest post-exposure periods. These two manifestations of oxygen-induced retinopathy are emphasized because they lead to an abnormal separation of the retina from the epithelial layer, which may increase the likelihood of the most serious consequence of ROP—retinal detachment. In fact, all rats that endured post-exposure periods of 38 days or longer before sacrifice exhibited retinal detachment.

ISSN:0271-3683    

DOI:10.3109/02713689209033492

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

One of the most prominent features of S-antigen induced uveitis is the massive infiltration of polymorphonuclear leukocytes (PMNs) and mononuclear cells in the ocular tissues and fluids. These inflammatory cells generate reactive oxygen metabolites as microbicidal agents and release these oxidants into the surrounding tissues. Using the cerium perhydroxide method, we have localized subcellular hydrogen peroxide in various inflamed ocular tissues. Most notably, the positive electron-dense granules were seen in the plasma membranes of PMNs that were infiltrating in the retina and uvea. These deposits were noted also in PMNs located within the extravascular spaces. For the intravascular PMNs, the positive reaction products were seen in much lower concentrations. A direct demonstration of substantial concentrations of hydrogen peroxide in experimental autoimmune uveitis, therefore, suggests the possibility that this reactive metabolite is an inflammatory mediator in this condition.

ISSN:0271-3683    

DOI:10.3109/02713689209033493

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

Previous studies have shown that ocular $aL2adrenoceptors are located pre junctionally on sympathetic neurons and post junctionally on cells in the iris/ciliary body. While the activation of $aL2adrenoceptors at each site has been postulated to alter aqueous humor dynamics, little is known about the pharmacological characteristics of these receptors or their role in the modulation of anterior segment function. The purpose of the current study was to determine the possible heterogeneity of ocular $aL2adrenoceptors using relatively selective $aL2adrenoceptor agonists and antagonists to examine ocular pre- and post junctional $aL2adrenoceptors. Prejunctional $aL2effects were evaluated by means of the cat nictitating membrane (CNM) preparation. Postjunctional $aL2effects were evaluated by means of the cAMP assay in rabbit iris root/ciliary body. In the CNM, the administration of UK-14,304 (UK) produced a dose-related inhibition of neuronally mediated contractions. Pretreatment with the $aL2antagonist rauwolscine caused a 1 to 2 log unit right shift in the dose-response curve of UK in the CNM. However, pretreatment with $aL2antagonist SKF 104078 had no demonstrable effect on UK-induced inhibition of neuronally mediated contractions of the CNM. In the rabbit iris root/ciliary body, UK produced a concentration-dependent inhibition of cAMP accumulation on isoproterenol- and VIP-induced cAMP production. Pretreatment of iris root/ciliary bodies with SKF 104078 or rauwolscine reversed the inhibitory effect of UK on Isoproterenol- and VIP-induced accumulation of cAMP. These data provide the first evidence that the pre- and post junctional $aL2adrenoceptors represent pharmacologically distinct subpopulations of receptors in the eye. Moreover, these data indicate that drugs such as SKF 104078 can be used to determine the relative contributions of pre- and post junctional $aL2adrenoceptors in the modulation of aqueous humor dynamics.

ISSN:0271-3683    

DOI:10.3109/02713689209033494

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

The Lens Opacities Classification System II (LOCS II) utilizes photographic standards (two retroilluminated Neitz-CTR and one standard slit lamp Zeiss photographs) for the classification of cortical and posterior subcapsular cataracts, nuclear color and nuclear opalescence. However, dedicated photographic devices, particularly retroillumination cameras, are not always available and this study was aimed at evaluating the suitability of a retroillumination photographic technique with a standard slit lamp camera for cortical and posterior subcapsular cataract classification according to LOCS II. Two observers examined 273 eyes. Kappa statistics demonstrated that agreement between the standard slit lamp, clinical grading (according to published LOCS II methodology) and photographic grading (according to our photographic technique), as well as inter- and intraobserver reproducibility, were excellent (Kappa>0.74) for the classification of all lenticular regions. The results indicate that a standard slit lamp camera can be as useful as a dedicated retroillumination camera when LOCS II standards are used for cataract classification.

ISSN:0271-3683    

DOI:10.3109/02713689209033495

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

Hyaluronan (hyaluronic acid) is a high molecular weight viscoelastic polymer which has been postulated to enhance wound healing. We investigated the dose and molecular weight (9×104- 280×104) dependent effects of hyaluronan on the rate of migration of rabbit corneal epithelium in organ culture and on wound closurein vivoafter debridement with n-heptanol. When corneal blocks were cultured with hyaluronan for 20 hours, distances of epithelial migration significantly increased over exposed stroma in proportion to hyaluronan concentration. However, there was no difference in the stimulatory action of hyaluronan on epithelial migration when corneal blocks were cultured at 1 mg/ml of hyaluronan irrespective of changes in the molecular weight range between 9×104and 280×104. Glycosaminoglycans other than hyaluronan (chondroitin, chondroitin sulfate, keratan sulfate and heparan sulfate) failed to increase the epithelial migration. When hyaluronan eye drops were instilled after corneal epithelial removal with n-heptanol, hyaluronan stimulated wound closure in a dose-dependent manner, but its stimulatory efficacy was not dependent on molecular weight.

ISSN:0271-3683    

DOI:10.3109/02713689209033496

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

Stimulation of cultured human trabecular meshwork cells by histamine caused time and dose related increases in inositol phosphates and intracellular free calcium. The increase in inositol trisphosphate (IP3) was immediate and calcium independent while that of inositol monophosphate (IP1) was gradual and calcium dependent. The rise in intracellular calcium was also rapid and occurred as a result of mobilization from intracellular stores and influx from external medium. Histamine also caused time and concentration related de novo synthesis of inositol phospholipids. Mepyramine but not cimetidine inhibited the action of histamine. These results indicate that histamine, via H1receptor, evokes an early hydrolysis of inositol phospholipids and increase in intracellular free calcium, signals which may be involved with the function of the trabecular meshwork cells.

ISSN:0271-3683    

DOI:10.3109/02713689209033497

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

Recently, growth factors are known to phosphorylate tyrosine residues of proteins to regulate cellular functions. We investigated growth factor-dependent phosphorylation of membrane proteins in cultured human retinal pigment epithelial (RPE) cells. The phosphorylation experiments were done in membrane preparations of cultured RPE cell and the reaction was started by applying [32P]adenosine 5′-triphosphate (ATP) at O°C, and terminated after 0, 1, 5, 15, and 30 min. The samples were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and were analyzed by autoradiography. Many proteins showed time-dependent phosphorylation. Among them, a 170 kDa protein showed platelet-derived growth factor (PDGF)-specific phosphorylation with both time- (up to 30 min) and dose- (maximal effect at 50 ng/ml) dependence. On the other hand, epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) showed no specific phosphorylation. Phosphoaminoacids of the 170 kDa protein were analyzed by thin layer chromatography and autoradiography. Phosphotyrosine showed much higher radioactivity than phosphoserine or phosphothreonine. Consequently, PDGF induced phosphorylation of the 170 kDa protein which mainly consisted of phosphotyrosine. The data suggest that tyrosine phosphorylation of membrane protein is involved in signal transduction of PDGF in human RPE cells.

ISSN:0271-3683    

DOI:10.3109/02713689209033498

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

Basic fibroblast growth factor (bFGF) delays photoreceptor degeneration when injected intraocularly in Royal College of Surgeons (RCS) rats with inherited retinal dystrophy. In the present study, we have determined the localization of endogenous bFGF in retinas of normal and RCS rats during the normal developmental period (postnatal days 0–20) and the period of photoreceptor degeneration in RCS rats (days 20–90). bFGF was localized immunohistochemically by indirect immunoperoxidase using two different polyclonal antibodies and one monoclonal antibody against bFGF. bFGF was present in retinas as early as birth, and remained through adult age. Controls using either PBS, non-immune IgG or antibody preabsorbed with bFGF peptide were devoid of label. In normal rats between the ages of birth and postnatal day (P) 4, bFGF was found in developing ganglion cells, superficial blood vessels, some of the innermost cells in the neuroblastic layer, developing horizontal cells, and retinal pigment epithelial (RPE) cells. Between P0 and P4, the intensity of staining increased significantly in horizontal cells. From P6-P10, some cells in the inner nuclear layer remained positive, but horizontal cell staining became less intense in the central retina. The superficial vessels, ganglion cells and RPE cells also remained positive for bFGF. At P20–25, when the retina was essentially mature, bFGF was found in RPE cells, most cells of the ganglion cell layer, and many cells of the inner nuclear layer, but horizontal cells and blood vessels showed a lower concentration of bFGF than they did at younger ages. At P45 and older, blood vessels no longer showed bFGF immunoreactivity. The staining pattern in RCS rats was indistinguishable from that for normal rats at all ages examined. These results show that bFGF is present in the developing and adult rat retina in some neural cells, in addition to vessels and RPE cells. The transient elevated expression of bFGF immunoreactivity in developing horizontal cells and blood vessels suggests a possible role for this growth factor in retinal development. In addition, if RCS retinas possess any difference in bFGF localization or concentration compared to normal retinas, it must be too small to detect by immunohistochemical means, or at least with the reagents used.

ISSN:0271-3683    

DOI:10.3109/02713689209033499

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor

摘要:

Freshly isolated bovine non-pigmented ciliary epithelial cells were studied using the whole-cell voltage-clamp and permeabilized patch techniques. In a study of 148 cells three classes of cell were found; those containing inward currents alone, 31%; those containing outward currents alone, 37% and those containing both inward and outward currents, 32%.The outward currents exhibited slow, delayed activation, were blocked by tetraethylammonium (TEA+) but were not effected by changes in [Cai] suggesting they are K+-currents similar to IK(V), the delayed rectifier. The inward currents were reduced by TEA+and blocked by Cs+suggesting they are inward rectifier K+-currents.Intracellular cAMP levels were increased by isoprenaline with a Kaof 20nM. However, the resting membrane potential recorded from whole ciliary processes in intracellular microeletrode studies was not effected by adrenergic stimulation, neither were the leak current, the outward current nor the sustained inward current significantly effected by isoprenaline, noradrenaline or dibutyryl-cAMP in whole-cell and permeabilized patch clamp studies.

ISSN:0271-3683    

DOI:10.3109/02713689209033500

出版商:Taylor&Francis    

年代:1992

数据来源: Taylor