Development Of Galactose Cataracts Research Articles

Ascorbate deficiency increases the rate of galactose-induced cataract formation in guinea pig: A study of the possible mechanism: Yokoyama, T., Sasaki, H., Giblin, F.J. and Reddy, V.N. Eye Research Institute, Oakland University, Rochester, MI 48309-4401, U.S.A.

An early decrease in 86Rb uptake was found in lenses of galactose-fed rats. Dissections in normal rat lenses showed that 86Rb acoumulation occurred in areas closer to the lens epithelium. The decreased uptake in lenses of galactosemic rats occurred in all lens areas; however, these lenses recovered their ability to accumulate 86Rb following galactose withdrawal from the diet.High dulcitol (galactitol) levels were found in lenses of galactose-fed rats. Dulcitol accumulations in the lens suggested a possible inhibitory role of this metabolite on the concentrating mechanisms of cations and amino acids in the lens during the development of galactose cataract in rats.

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. This was done on normal lens epithelia and on epithelia from lens of rats fed a diet of Purina Chow containing 50% galactose for periods of from 6 hr to 20 days. We found AR mRNA to elevate to about 5-fold the control levels by 12-24 hr on galactose, then decrease to the control levels by day 4. The increase in AR mRNA appears to be transitory. The high abundance in AR mRNA by 24 hr on galactose was confirmed by in situ hybridization. At later periods, from 8 to 20 days on galactose, a slow increase in AR mRNA took effect, as we have previously reported. Changes in the levels of galactose and dulcitol between 0 and 96 hr were also quantitated by gas chromatography, showing that there was a significant increase in both galactose and dulcitol occurring throughout the experimental period.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of sodium iodate injection on the development of galactose cataract in the rat.

The effect of sodium iodate injection on the development of galactose cataract in the rat was investigated clinically and biochemically. Galactose cataracts were induced in animals which had been injected with a single dose of sodium iodate and compared with those given a saline injection. The degeneration of retinal pigment epithelium was observed electron microscopically after sodium iodate injection. A slit lamp examination of the lens showed that, in animals injected with sodium iodate, galactose-associated lens alterations progressed faster, and mature cataract development was achieved earlier than in the saline-injected animals. Biochemical data which indicated a significantly higher concentration of Na+ and lower concentration of K+ in lenses of sodium iodate-injected animals confirmed the above clinical data. The level of galactitol was higher in lenses of sodium iodate-injected than those of saline-injected animals. Acceleration of the development of galactose cataract following sodium iodate injection is apparently due to the higher level of galactose entering the aqueous humor because of breakdown of blood-ocular barriers.

Rubidium-86 accumulation and dulcitol distributions in lenses of galactose-fed rats

An early decrease in 86Rb uptake was found in lenses of galactose-fed rats. Dissections in normal rat lenses showed that 86Rb acoumulation occurred in areas closer to the lens epithelium. The decreased uptake in lenses of galactosemic rats occurred in all lens areas; however, these lenses recovered their ability to accumulate 86Rb following galactose withdrawal from the diet. High dulcitol (galactitol) levels were found in lenses of galactose-fed rats. Dulcitol accumulations in the lens suggested a possible inhibitory role of this metabolite on the concentrating mechanisms of cations and amino acids in the lens during the development of galactose cataract in rats.

Synthesis of Creatine Phosphate by the Crystalline Lens : In normal conditions and during the development of galactose cataract

Synthesis of Creatine Phosphate by the Crystalline Lens : In normal conditions and during the development of galactose cataract

Glucose-6-phosphate dehydrogenase and aldolase in lenses of lactose-fed rats.

IT has been shown that in lenses of galactose-fed rats there is a decrease of glucose-6-phosphate dehydrogenase1,2 and aldolase3. These findings support the statement that there is an interference of glucose metabolism in the lens during the development of galactose cataracts. In the previous experiments2 glutathione reductase was also determined as a coupled system with the glucose-6-phosphate dehydrogenase through the utilization of the oxidized and reduced forms of nicotinamide-adenine dinucleotide phosphate (NADP). The activity of the glutathione reductase was reduced similarly to the glucose-6-phosphate dehydrogenase. Incubation of normal lens homogenate with galactose or galactose-1-phosphate showed no inhibitory effect on the glucose-6-phosphate dehydrogenase or aldolase activities2,3. Considering these results, and also that a lowered amount of soluble proteins per mg lens was found in the lactose-fed rats3, we came to the conclusion that this was due to a decreased protein synthesis in lenses in this condition. However, aldolase was more affected than glucose 6-phosphate dehydrogenase, which may indicate a more direct action on the glycolytic pathway, which is, quantitatively, the most important pathway of glucose metabolism in lens4. The former experiments were performed independently with two different sets of rats. In order to know which of the two pathways is affected first, another group of animals was examined.

Hypophysectomy effect on lens epithelium mitosis and galactose cataract development in rats.

Introduction Endocrine disorders, such as diabetes and hypoparathyroidism, are known to be associated with cataracts in both human and experimental eyes. 1-3 The possible effects of other endocrine glands on the lens stimulated the present series of experiments. As a preliminary approach to the problem, the effects of hypophysectomy on the mitosis of the lens epithelium and on the development of galactose cataract in the rat were studied. The different criteria utilized to evaluate possible alterations in the lens were (1) the number of mitotic cells in the lens epithelium in static conditions and after colchicine administration; (2) biomicroscopic changes; (3) lens transparency, and (4) the level of total plasma-reducing sugar before and after yeast incubation. Material and Methods Male albino rats (weight 150 gm. at the beginning of each experiment) were obtained from the Hormone Assay Laboratory (Chicago). Hypophysectomized and control animals were born on the same day and

Studies on Protein and Protein Synthesis : During the Development of Galactose Cataract

Studies on Protein and Protein Synthesis : During the Development of Galactose Cataract

Effect of cocarboxylase on the development of galactose cataract in rats.

Effect of cocarboxylase on the development of galactose cataract in rats.