UVA light in vivo reaches the nucleus of the guinea pig lens and produces deleterious, oxidative effects.

The possible role of ultraviolet light in the formation of cataract is not well understood. In this study, guinea pigs were exposed to a chronic, low level of UVA light (0.5 mWcm(-2), 340-410 nm wavelength, peak at 365 nm) for 4-5 months.

Glutathione peroxidase-1 deficiency leads to increased nuclear light scattering, membrane damage, and cataract formation in gene-knockout mice.

Purpose: Previous in vitro studies with transgenic and gene-knockout mice have shown that lenses with elevated levels of glutathione peroxidase (GPX)-1 activity are able to resist the cytotoxic effect of H(2)O(2), compared with normal lenses and lenses from GPX-1-deficient animals. The purpose of this study was to investigate the functional role of this enzyme in antioxidant mechanisms of lens in vivo by comparing lens changes of gene-knockout mice with age-matched control animals.

Methods: In vivo lens changes were monitored by slit lamp biomicroscopy, and enucleated lenses were examined under a stereomicroscope in gene-knockout animals and age-matched control animals ranging in age from 3 weeks to 18 months.

Effect of pretreatment of germanium-132 on Na(+)-K(+)-ATPase and galactose cataracts.

Purpose: Recently, we reported that topical administration of 2-carboxyethyl germanium sesquioxide (Ge-132) concurrently with 50% galactose feeding delayed the establishment of mature cataracts and reduced advance glycation product. This study was to determine the effect of pretreatment of Ge-132 on galactose associated morphological changes and Na(+)-K(+)-ATPase activity.

Methods: Young Sprague Dawley rats received topical eye drops four times a day of either saline or Ge-132 seven days prior to the 50% galactose diet and during galactose feeding.

Effect of germanium-132 on galactose cataracts and glycation in rats.

Germanium compounds have been shown to be effective in preventing the formation of advanced glycation end-products and for reversible solubilization of glycated proteins. As protein glycation has been proposed to play a role in lens opacification, we initiated studies to evaluate the effects of 2-carboxyethyl germanium sesquioxide (germanium compound 132 or Ge-132) on galactose-induced cataractogenesis. For this study young Sprague-Dawley rats were fed a 50% galactose diet.

Nuclear light scattering, disulfide formation and membrane damage in lenses of older guinea pigs treated with hyperbaric oxygen.

Nuclear cataract, a major cause of loss of lens transparency in the aging human, has long been thought to be associated with oxidative damage, particularly at the site of the nuclear plasma membrane. However, few animal models have been available to study the mechanism of the opacity. Hyperbaric oxygen (HBO) has been shown to produce increased nuclear light scattering (NLS) and nuclear cataract in lenses of mice and human patients.

Lenticular alterations in hypertensive rats.

Cataract development has been reported in Dahl salt-sensitive (DS) hypertensive rats with high-salt intake. An alteration in ionic transport and electrolyte balance has been reported to be associated with hypertension in these animals. A morphological evaluation of the lenses of salt-sensitive 'cataract-prone' (DS) and salt-resistant (DR) control animals is lacking.

Elemental studies in rat lens during galactose cataract reversal.

Alterations in elemental composition of the normal lens have been reported to accompany galactose cataract development in rats. In this report we present the changes in regional distribution of Na, K, Cl, P, S and Ca during the reversal of galactose-induced cataracts. Elemental X-ray maps of lenses from young female Sprague Dawley rats fed 50% galactose for 20 days were examined at 0, 20, 40 and 90 days following the transfer of galactose fed rats to Purina Rat Chow diet.

Aldose reductase inhibitors and galactose toxicity in neonatal and maternal rat lenses.

We reported that in utero galactose-induced cataracts could be inhibited if aldose reductase inhibitors (ARIs) were included in the galactose diet of pregnant rats. These studies involved morphological and cytochemical approaches. We undertook this investigation to evaluate the effects of ARIs in preventing the formation, accumulation and depletion of dulcitol in lenses of in utero galactose exposed neonates and in mothers during and following pregnancy.

Transient elevation of aldose reductase mRNA in lens of rats developing galactose cataracts.

Aldose reductase (AR), a major enzyme in the polyol pathway, is thought to be responsible for accumulation of polyols in lenses exposed to high doses of galactose or glucose, and it may be linked to some of the complications found in diabetes. In this report we examined the level of expression of AR mRNA in lens epithelia undergoing development of galactose cataracts in vivo. The AR mRNA was quantitated by Northern blot hybridization with a [35S]-RNA transcript from a previously described AR cDNA clone.

Expression of c-myc protooncogene in rat lens cells during development, maturation and reversal of galactose cataracts.

It is well established that normal patterns of epithelial cell proliferation and metabolism, and of fiber cell differentiation and maturation are essential for the maintenance of transparency in the ocular lens. Several factors, including exposure to high levels of sugars, have been known to result in the compromise of lens transparency. For example, initiation of lens cell damage by galactose induces lens epithelial cells to proliferate.

Effect of aldose reductase inhibitors on lenticular dulcitol level in galactose fed rats.

We have shown that galactose cataract development is delayed or inhibited with the administration of aldose reductase inhibitors (ARIs). Dulcitol forms and accumulates in the lens of rats fed galactose. We undertook investigations to study the effectiveness of ARIs in preventing the formation and accumulation of dulcitol in the lens.

Alterations in lens permeability during galactose cataract development in rat.

Lens permeability has been shown to be compromised during galactose-induced cataract development in rats. Recent studies have demonstrated permeability and diffusion pathways as well as endocytotic activity in normal lenses of different species using tracers of different molecular weights. We investigated the permeability and diffusion of tracers in normal rat lenses and in lenses during cataract development using three different molecular weight tracers, lanthanum nitrate (LN, MW 430), ruthenium red (RR, MW 858.

In utero and milk-mediated effect of aldose reductase inhibitor on galactose cataracts.

Our previously reported investigations showed that cataracts could be induced in fetal lenses through the maternal feeding of galactose during pregnancy. We also reported that the lens opacity present at birth reverses completely by 30 days of age if there is no further post-natal exposure to galactose. This investigation was designed to investigate if an aldose reductase inhibitor (ARI) has any cross-placental effect in preventing galactose-induced cataracts in fetuses.

Crystallin mRNA concentrations and distribution in lens of normal and galactosemic rats. Implications in development of sugar cataracts.

It is well established that high concentrations of sugar in the lens of the eye eventually lead to fiber cell destruction and cataracts. In these studies the decrease in crystallin mRNAs was quantified as a result of influx of high concentrations of galactose into the lens of rats. The alpha A-, alpha B1-, and gamma-crystallin mRNA concentrations were assessed in normal lens and in lens undergoing development of sugar cataracts by northern blot and in situ hybridization methods.

Evaluation of lens epithelial cell differentiation by quantitation of MP26 mRNA relative to gamma-crystallin mRNA in initiation of galactose cataracts in the rat.

It is well established that in response to feeding of galactose to four-week-old rats cataracts develop (Unakar, Genyea, Reddan & Reddy, Exp. Eye Res. 26, 123-33, 1978).

Permeability studies in neonatal rat lens epithelium.

Lanthanum nitrate (LN) and horseradish peroxidase (HRP) were used as tracers to study intercellular permeability as well as the existence and location of tight junctions and changes in them, if any, in the lens epithelium of Sprague Dawley rats. Thin sections of lenses taken from animals at birth and at three day intervals until the neonates were weaned at approximately 22 days were studied at the electron microscope level. At every age both tracers permeated the intercellular spaces of the anterior region epithelium and between the fiber cells of the equatorial region.

Aldose reductase mRNA is an epithelial cell-specific gene transcript in both normal and cataractous rat lens.

Aldose reductase (AR) is implicated in the development of sugar cataracts by its reduction of galactose or glucose to polyols. The authors' recent work suggested that AR mRNA is found to be expressed in high concentrations in rat-lens epithelial cells after exposure of the animal to a diet containing 50% galactose. They localized the AR mRNA in the lens cells by in situ hybridization with a previously described AR clone.

Management of aldose reductase mRNA abundance in rat lens undergoing reversal of galactose induced cataracts. A model for gene response to changes in the environment.

Aldose reductase (AR) mRNA concentration in rat lens was quantitated by hybridization of a RNA transcript from a previously described AR cDNA clone to mRNA found in epithelial and cortical cytosols. This was done on normal rat lens and on lens initially made cataractous by feeding of a diet of Purina Chow containing 50% galactose, followed by reversal of the cataracts due to the removal of the galactose from the diet. Recent data from this laboratory has shown that AR mRNA was increased in lens epithelial cells upon administration of galactose; while in the cortex it was reduced to insignificant levels when fiber cell damage became extensive by day 20 on galactose.

Reversal of the limited proteolysis of MP26 during the reversal and prevention of the galactose cataract in rat lenses.

The reversal and prevention of the galactose-induced cataract in rats were employed to study their effects on the acceleration of the limited proteolysis of MP26 into MP23-24 previously observed in cataractous lenses of galactose-fed animals. Lenses of rats on a cataract reversal-diet demonstrated the reversal of MP23-24 and MP26 levels to control levels in the clearing cortical areas but not in remaining cataractous nuclear areas. Acceleration of the limited proteolysis of MP26 was observed in the nucleus but not the cortex in the clear lenses of animals on a cataract prevention-diet.

Relative abundance of aldose reductase mRNA in rat lens undergoing development of osmotic cataracts.

Aldose reductase (AR) messenger RNA concentration was determined in normal rat lens and in lens from rats fed a 50% galactose diet over a period of 20 days. The AR mRNA was detected by using a previously described AR cDNA clone. The relative concentration of the AR mRNA was estimated by cpm of 35S-UTP labeled antisense RNA hybridized to dot-blots prepared from cytosols isolated from single lens, decapsulated lens (cortex) and its respective capsule (epithelia).

Prefeeding of aldose reductase inhibitor and galactose cataractogenesis.

Our recent investigations have shown that the Eisai compound, E-0722, (2R-4S-6-fluoro-1-2-methylspirochroman 4,4'-imidazolidine 2,5'-dione) is a more potent aldose reductase inhibitor than Sorbinil (D-6-fluorospirochroman 4,4'-imidazolidine 2,5'-dione). In the previous studies these aldose reductase inhibitors were added to the 50% galactose diet fed to rats to determine their effect on galactose-induced alterations in the lens and the development of cataract. In this report we present our results on the effect of prefeeding the aldose reductase inhibitor, E-0722, on the alterations in rat lens following subsequent feeding of galactose.

Aldose reductase inhibitors and prevention of galactose cataracts in rats.

Our previous studies have shown that the aldose reductase inhibitor (ARI), sorbinil, prevents galactose-induced alterations and cataracts in rat lenses. We have now used sorbinil as well as another ARI, Eisai compound E-0722, to determine their potency in inhibiting aldose reductase- and galactose-induced alterations in lens morphology and Na+-K+-ATPase activity. Young Sprague Dawley rats were fed Purina Rat Chow plus 50% galactose, with or without 15 mg sorbinil, 0.

Histochemical localization of catalase in cultured lens epithelial cells.

The diaminobenzidine (DAB) technique was used to investigate the localization of the peroxidatic activity of catalase in cultured lens epithelial cells at the ultrastructural level. Cultured rabbit, bovine and mouse lens epithelial cells incubated in an alkaline DAB reaction mixture contained catalase-positive microperoxisomes which were randomly distributed throughout the cytoplasm. The reaction product of catalase was abolished when cells were treated with 3-amino-1-H-1,2,4-triazole, a specific inhibitor of catalase, and was not detected when DAB or H2O2 was omitted from the incubation medium, or when the pH of the reaction mixture was lowered to 7.

Elemental and structural studies of the rat galactose cataract.

A series of rat galactose lenses, from 1 to 20 days on the 50% galactose diet, were frozen in the whole eye, and fractured from pole to pole in the frozen state. Lyophilized half-lenses were prepared for analysis by energy dispersive spectrometry (EDS). Following elemental analysis, some specimens were embedded and sectioned for histological studies.