الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 192 |  |  |
| | | from | 192 | | |
Abstract
Cataract (or opacity of the crystalline lens) is one of the major
causes of impaired vision and blindness worldwide affecting more than
17 million people around the world. Cataractogenesis is one of the often
seen consequences of aging process, and diabetes mellitus is a major risk
factor for the development of cataract at an early age compared to senile
cataract.
Advanced glycation end products (AGEs) are heterogeneous
fluorescent derivatives formed by the Maillard process, a non-enzymatic
reaction between the reducing sugars and the free amino groups of
proteins, lipids and nucleic acids. AGEs play a pivotal role in
cataractogenesis. Production of AGEs takes place throughout the normal
aging process but its accumulation is found to be accelerated in diabetes.
Advanced glycation end products formation and cataract
progression are extremely slow processes and are triggered in the
presence of free radicals. Oxidative stress along with AGEs may integrate
resulting in acceleration of cataract formation.
Obesity has also been proposed to be a risk factor for cataract
development. Obesity has been linked to cataract by its associated
complications such as diabetes.
The purposes of this study are to investigate the potential role of
advanced glycation end products (AGEs) in age-related (senile) and
diabetic cataract subjects. In addition, this study is designed to determine
the possible role of obesity in the development and progression of
diabetic cataract. This study was conducted according to the Ethical
Committee Approval of the Research Institute of Ophthalmology, Egypt
on 40 patients, 20 of them were senile cataract patients. The other 20
patients were diabetic cataract, in addition to 20 subjects served as control
group. The body mass index (BMI) was measured and the levels of FBG,
HbA1c, MDA, TAC, GSH, SOD, and AGEs were determined in all
subjects.
Also, a comparative experimental study was performed on 40 rats
for the detection of the modification of lens crystallin with glycation and
obesity. The animals were divided into four groups of 10 animals each:
control (group I); diabetic (group II) injected with a dose of 40 mg/kg by
streptozotosin, high fat diet (Group III) were access to high fat diet and
(Group IV) were access to a high fat diet and injected individually with a
dose of 40 mg/kg by streptozotosin.
There was no significant change in the body mass index (BMI)
among the groups. There were significant increases in FBG and HbA1c
in the diabetic cataract group compared to senile cataract and control
groups. However, there was statistical significant increase in plasma
MDA and AGEs levels in both the senile and diabetic cataract groups
compared to control group. On the other hand, there were significant
decreases in TAC, GSH, SOD activities in both the senile and diabetic
cataract groups compared to control group.
In the experimental study, there was a statistical significant
increase in FBG, HbA1c, MDA and AGEs levels in diabetic and HFD
groups compared to control group. However, there were statistical
significant decreases in GSH and SOD activities in diabetic and HFD
groups compared to control group. On the other hand, there were
statistical significant decreases in TAC level and total lens protein in
diabetic groups compared to control group but no significant decrease in
123 Summary and Conclusion
TAC level and total lens protein in HFD group compared to control
group.
Sodium dodecyl sulfate (SDS) electrophoresis showed aggregation
of lens proteins in the diabetic groups compared to HFD and control
groups. This aggregation of lens proteins is an indicator of accelerated
cataractogenesis.
In conclusion, this study clearly demonstrated increased
accumulation of AGEs, and increased lipid peroxidation products along
with impaired antioxidant status in patients with both diabetic and senile
cataract. Proper control of hyperglycemia, blocking of AGEs pathways
by AGEs-inhibitors and low fat diet may be beneficial to delay cataract
development.