Spectroscopic and biochemical correlations during the course of human lens aging.
BACKGROUND
With age, the human lens accumulates variety of substances that absorbs and fluorescence, which explains the color of yellow, brunescent and nigrescent cataract in terms of aging. The aim of this study was to assess lens fluorophores with properties comparable to those of advanced glycated end products (AGEs) in relation to age in human lenses. These fluorescent compounds are believed to be involved in the development of cataract.


METHODS
Spectroscopic (UV-Vis-NIR) and fluorescence photography (CCD-Digital based image analysis) studies were carried out in randomly selected intact human lenses (2-85 years). AGE-like fluorophores were also measured in water soluble and insoluble (alkali soluble) fractions of human lenses (20-80 years).


RESULTS
Our experimental findings suggest that there was a progressive shift in the absorbance characteristic of intact lens in the range of lambda210 nm-lambda470 nm. A relative increase in the absorptivity at lambda(511-520 nm), with age, was also observed. In addition, the ratio of absorptivity at lambda(511-520 nm) versus the maximum absorbance recorded at blue-end cut-off (210-470 nm) was also found to increase, with age. The fluorescent intensity in the intact lens at both UV-B (lambdaEx312 nm) and UV-A (lambdaEx365 nm) were found to be positively correlated (r2 = 0.91 & 0.94, respectively; Confidence interval 95%) upto 50 years of age. In addition, a concomitant changes in AGE- like fluorophores were also observed in the processed lens samples (soluble and insoluble fractions) along the age. A significant increase in the concentration of AGE- like fluorophores, both in intact and processed lens was observed during the period of 40 - 50 years.


CONCLUSIONS
Based on the present investigation, it was concluded that significant changes do occur in the AGE-like fluorophores of human lenses during the period of 40-50 years.
Ranjan
Mala
M
Department of Biochemistry, University College of Science, Osmania University, Hyderabad- 500 007 (A.P.), India. ranjanmalarai@rediff.com
Beedu
Sashidhar Rao
SR
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D005453:Fluorescence; D017127:Glycation End Products, Advanced / Q000378:metabolism*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007908:Lens, Crystalline / Q000378:metabolism*; D008875:Middle Aged; D013057:Spectrum Analysis
D017127:Glycation End Products, Advanced