摘要:

The effects of adrenergic drugs on intracellular electrical potential difference (PD) of rabbit ciliary epithelial cells were investigated. Epinephrine as well as norepinephrine hyperpolar-ized the PD at lower concentrations (10−6M) and depolarized the PD at higher concentrations (>10−5M). Isoproterenol produced a depolarization of PDIand phenylephrine caused a hyperpolar-ization only. After pretreatment with propranolol, the change of PDIby isoproterenol was minimal. Selective agonists and antagonists were used to further characterize adrenergic effects on the PDI. Both beta1, and beta2agonists caused a depolarization of PDIwhile both beta2. and beta2antagonists produced a hyperpolarization. Alpha1, antagonist depolarized the PDIand alpha2antagonist hyperpolarized the PDI. Such electrophysiological effects of the adrenergic drugs confirm the presence of alpha and beta adrenoceptors in the rabbit ciliary epithelial cells.

ISSN:0271-3683    

DOI:10.3109/02713689009000049

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

The damaging effects of continuous light exposure to the albino rat retina have been well documented. However, the cumulative effects of multiple light exposures are not well defined. We therefore compared the retinal injury induced by a single 24 hour light exposure with that caused by three intermittent exposures of 8 hours each. Eight dark-adapted albino Lewis rats were exposed for 24 hours to green fluorescent light (490–580 nm) at an illuminance level of 175 foot-candles. A second group of 8 rats was exposed under similar conditions in three split doses of 8 hours each at intervals of 7 days between each exposure. Recovery was allowed in total darkness, and the animals were sacrificed 2 weeks following the last exposure. Retinal damage was assessed by morphometry and light and electron microscopy. Mild cumulative retinal injury, mostly in photoreceptor cells with relative sparing of the retinal pigment epithelium, was seen in the split dose group, while extensive damage involving photoreceptor cells and retinal pigment epithelium was noted in the group exposed continuously for 24 hours.

ISSN:0271-3683    

DOI:10.3109/02713689009000050

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

Fresh isolates of neonatal human corneal endothelial cells were maintained in tissue culture using a technique employing collagen-coated, dextran-based microcarrier beads. This method provides large yields of endothelial cells suitable for biochemical and/or transplant studies without exposing the cells to enzymatic passage. Our results suggest that microcarrier culture of human corneal endothelial cells can provide a usefulin vitrosystem for the growth and maintenance of actively mitotic cells.

ISSN:0271-3683    

DOI:10.3109/02713689009000051

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

Cultured cells derived from transgenic animals have not generally been utilized to investigate questions in cell biology; however, to study the properties of proteins from the lens of the eye, a cell line which synthesizesα-crystallin was established from a transgenic mouse. All theα-crystallins,αA,αB, and alnsert, accumulate in the cell line. Theα-crystallin, 1.6% of the cellular protein, is found in large molecular weight aggregates similar to the aggregates found in the normal mouse lens. Theα-crystallins in the lens cells correspond exactly to both the unmodified and the phosphorylatedα-crystallins found in the lens of the mouse, suggesting that some post-translational modification of the mouseα-crystallin may be important to the structure of this protein.

ISSN:0271-3683    

DOI:10.3109/02713689009000052

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

The purpose of this study was to provide a direct assay for calpain and its endogenous inhibitor calpastatin in normal rabbit epithelium. Corneal epithelial extracts were fractionated by DEAE (1) chromatography on HPLC. Fractions were analyzed for calpain by ELISA, immunoblotting, and caseinolytic enzyme activity with FITC-labeled casein. Results demonstated Immunoreactive peaks for calpains I and II. Calpain II from the soluble fraction of corneal epithelium eluted at a similar NaCl concentration (260 raM) as calpain II from other tissues, was inhibited by both E64 and the removal of Ca, contained an 80 kDa subunit in immunoblots, and was present at specific activity of 220 units/g protein (in a crude homogenate). Calpain antigen was also present in the EDTA/EGTA washed insoluble fraction of corneal epithelium. Calpastatin in corneal epithelium eluted at 130 -160 mM NaCl on DEAE, coeluted with calpain I, and was present at 330 units/g protein (crude homogenate). The results demonstrated a calpain/calpastatin system in corneal epithelium, where it is speculated to play a role in epithelial cell turnover and wound healing.

ISSN:0271-3683    

DOI:10.3109/02713689009000053

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

This investigation examined many parameters during the course of early development of naphthalene-induced cataract in a time span of 0 to 79 days of treatment. Feeding naphthalene daily to Black-Hooded rats resulted in gradual progressive development of cataract. The first faint opacities were detectable after 7 days. Free soluble total glutathione (oxidized and reduced) of these lenses was shown to gradually decrease to a maximum loss of about 20%, a value reached by day 30 of treatment.No activity loss of either enzyme required for glutathione synthesis (γ-glutamylcysteine synthetase or glutathione synthetase) was observed in homog-enates of naphthalene versus control lenses. There was also neither impairment of [35S]-L-cystine uptake nor of [35S]-glutathione synthetic capacity in lenses cultured from rats after 12, 24 or 36 days of naphthalene feeding when compared to control lenses. Hence, glutathione loss cannot be explained by a damaged glutathione synthesis system.Progressive activity loss of glutathione peroxidase and glutathione reductase was observed. The loss of glutathione peroxidase activity was especially remarkable. Thus, the defense system against oxidative damage is impaired and may be a significant factor in naphthalene-induced cataract of the rat.

ISSN:0271-3683    

DOI:10.3109/02713689009000054

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

This investigation was concerned with factors which would maximize and inhibit L-cyst(e)ine uptake and glutathione synthesis of rat lenses cultured for 24 hours in a medium containing [35S]-L-cystine. The lenticular protein-free extract was separated and quantified by use of HPLC equipment which included an in-line radioisotope detector coupled with extensive post-run computer analysis.Six thiols were assessed for their ability to increase the uptake of L-cyst(e)ine and its utilization for glutathione synthesis. The most successful was 2-mercaptoethanol, which increased the L-cyst(e)ine uptake 3.6-fold and glutathione synthesis 2.9-fold. This work demonstrated that the rate of glutathione synthesis was directly proportional to the rate of uptake of L-cyst(e)ine.An inhibitor of glutathione synthesis, buthionine sulfoximine, in a concentration range of 0.11-3 mM, decreased uptake of the [35S]-label by one-third. The 3.0 mM concentration inhibited glutathione synthesis 98.7% and decreased glutathione 51% in 24 hours. The data indicate that half the glutathione disappeared in 23 hours in these cultured rat lenses. Because determination of this value did not depend upon the variable rate of cysteine transport, the value may approximate thein vivovalue.

ISSN:0271-3683    

DOI:10.3109/02713689009000055

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

Rod outer segment (ROS) phagocytosis by ex-planted bovine retinal pigment epithelium (RPE) was evaluated by a procedure using an indirect double radioimmunoassay which distinguished between ROS attached to the RPE cell surface and those which had been ingested. This approach has been used to investigate the effect of a variety of glycoconjugates on the phagocytic process. Inclusion of the glycosaminoglycans (GAGs) chondroitin sulphate type-A (CS-A) and type-C (CS-C), hyaluronic acid (HA) or dermatan sulphate (DS) in the incubation medium significantly inhibited the ingestion phase of ROS phagocytosis, whereas the binding phase was inhibited to a lesser extent. The interphoto-receptor matrix (IPM), containing these GAGs as part of proteoglycans, also had an inhibitory effect on phagocytosis. The free monosaccharides mannose, fucose and galactose all stimulated the ingestion of ROS by RPE cells. These findings support the suggestion that glycoconjugates may have a physiological role in the photoreceptor renewal process.

ISSN:0271-3683    

DOI:10.3109/02713689009000056

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

To further clarify the role of epidermal growth factor (EGF) in the physiology and pathophysiology of the ocular surface the effects of reflex tearing on concentrations of EGF in tear fluid were studied. Tear fluid samples were collected with glass capillaries before (basal samples, 59 eyes, 30 individuals) and during reflex tearing (stimulated samples, n=212, 40 eyes, 20 individuals). The rate of tear fluid flow in the capillaries (TFFc) was measured. The concentrations of human EGF (hEGF) was determined by time-resolved immunofluorometric assay (TR-IFMA). The first basal samples contained higher concentrations of hEGF than the samples from the contralateral eyes (n=28) collected thereafter (p<0.05). The basal samples from 40 eyes contained a significantly higher mean concentration of hEGF (8466 pg/ml) than did the stimulated samples (n=212, 2763 pg/ml); p<0.001). The mean TFFc increased from 63 nl/s to 506 nl/s during reflex tearing (p<0.001) and the amount of hEGF released from 567 fg/s (n=40) to 1400 fg/s (n=212; p<0.001). Basal samples from females contained higher concentrations of hEGF than did those from males. The maintenance of the hEGF concentration at a certain level and the increased amount of hEGF released into the tear fluid during reflex tearing suggests continuous release of hEGF into tear fluid from the lacrimal gland.

ISSN:0271-3683    

DOI:10.3109/02713689009000057

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

The subset distribution of lymphocyte populations isolated from rat lacrimal glands (LG) was compared with those from tissues of both mucosal and non-mucosal origin. In spleen (SPL), mesenteric (MLN) and cervical lymph node (CLN) populations the percentages of cells bearing W3/13 (pan T) and OX19 (pan T) were greater than the percentages obtained for cells bearing the 0X7 (Thy-1) marker. In contrast, for lacrimal (LG), salivary (SG) and mammary gland (MG) populations, cells bearing OX7 predominated over those bearing the W3/13 and 0X19 markers, with the exception of day 1 post-partum MG tissue which displayed equal numbers of OX7 and 0X19 cells. Except for MG, in which OX8 (T non-helper) predominated over W3/25 (T helper) populations, the proportions of these two subsets in the other tissues were generally similar. Analysis of SPL and LG cells for coexpression of OX7 with OX19 or L chain indicated that significant percentages of OX7 bearing cells also expressed I or J cell markers. However, the higher values noted for the OX7 population in LG were not attributable to increased numbers of cells coexpressing pan T or B cell markers. These findings show that lymphocyte subset distribution in LG and other glandular mucosal tissues is distinct from that of non-mucosal tissues, in that mucosal tissues contain a predominance of cells bearing the Thy-1 (OX7) phenotype.

ISSN:0271-3683    

DOI:10.3109/02713689009000058

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor