Development of cataract caused by diabetes mellitus: Raman study

Abstract

Diabetes mellitus succeeded by diabetic cataract was induced to experimental animals (Wistar rats) by applying an Alloxan injection. Eye properties deterioration were monitored from clinical standpoint and using Raman and infrared spectroscopies. All cases of developed cataract were followed by important changes in vibrational spectra, but Raman spectroscopy proved to be more useful because of larger number of resolved bands. Each kth Raman spectrum of diseased lens (in our notation k denotes disease age and cataract degree as described in chapter Alloxan diabetes) can be expressed as a sum of the Raman spectrum of healthy lens, I R , multiplied by a suitable constant c k , and the fluorescent background spectrum, I FB . We introduce the ratio of integrated intensities I FB and c k *I R as a physical parameter called fluorescent background index F FB . It turns out that F FB grows as cataract progresses and has its maximum at approx. 4, whence it decreases. F FB values are larger for 200-1800 cm −1 spectral interval than for 2500-4000 cminterval.In the same manner another quantity called water band index F W is defined for each Raman spectrum of diseased lens in the 2800-3730 cm −1 interval. It is the ratio of the integrated intensity from 3100 to 3730 cm −1 (water band interval) divided by the integrated intensity of the 2800-3100 cm −1 interval (C-H stretching region). F W increases monotonously with cataract progression with maximum at the end of monitored period (5 months).These two indices helped us to formulate a model describing disease development from the earliest molecular changes to its macroscopic manifestation. As glucose and other small saccharide molecules enter the lens tissue, they bind to crystallin and other proteins via O -and Sglycosidic linkages which occur probably at tyrosine and cystein sites. In Raman spectrum this corresponds to broad bands at 540 and 1100 cm −1 which grow together with the fluorescent background, because both contributions originate in nonenzimatically glycated proteins. The maximum of possible binding ends after approximately 4 months (cataract degree 4), but the water continues to enter the tissue and resides in water agglomerates.The lens impairing caused by fluorescent light scattering on aberrant glycoproteins and other fluorescent centers appears first and is usually associated with the ageing cataract, while deterioration of lens properties caused by increased binding of water steadily rises with glucose Furić, K., Mohaček-Grošev, V., Hadžija, M. (2005), ''Development of cataract caused by diabetes mellitus: Raman study '' Journal of Molecular Structure, and is characteristic of diabetic cataract. This interpretation is in agreement with electron microscopy results of other groups and with our preliminary findings obtained with light microscopy.

Water ice at low temperatures and pressures: New Raman results

“…The presence and the structure influence of water was investigated and published in several articles, see only for example: destruction of oxides [22], temperature, salinity measurement, See mucilage-blooming excesses [23][24][25], water in the mineral [26], cataract lens deterioration [27], polymer's structural (de)stabilization [28], and Ni-complex polymorphism [29]. To complete our work we paid also significant attention to the similar topic: Pure water -low temperatures; that results are presented here for the first time.…”

Confocal Raman microscopy can quantify advanced glycation end product (AGE) modifications in Bruch's membrane leading to accurate, nondestructive prediction of ocular aging

“…Combining Raman spectroscopy with optical microscopy allows acquisition of highly detailed chemical, physical, and biochemical data on a micron scale of spatial resolution without tissue destruction. So far there have been no published characterizations of AGE accumulation using Raman spectroscopy, although the technique has been used to detect diabetes-related changes in vitreous samples from patients with diabetic retinopathy (16), to analyze cataract formation and AGE precursor formation in diabetic lenses (17), and for in situ monitoring of macular carotenoid pigments (18,19). The development of confocal Raman microscopy as a noninvasive, robust method for the valid identification and quantification of AGEs offers considerable diagnostic potential for analysis of these pathogenic agents in ocular tissues.…”