Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0086543 (cataract)
 29,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To assess the significance of glycation, nonenzymatic browning, and oxidation of lens crystallins in cataract formation in elderly diabetic patients, we measured three distinct products of glycation, browning, and oxidation reactions in cataractous lens crystallins from 29 diabetic patients (mean +/- SD age 72.8 +/- 8.8 yr) and 24 nondiabetic patients (age 73.5 +/- 8.3 yr). Compounds measured included 1) fructoselysine (FL), the first stable product of glycation; 2) pentosidine, a fluorescent, carbohydrate-derived protein cross-link between lysine and arginine residues formed during nonenzymatic browning; and 3) N epsilon-(carboxymethyl)lysine (CML), a product of autoxidation of sugar adducts to protein. In diabetic compared with nondiabetic patients, there were significant increases (P less than 0.001) in HbA1 (10.2 +/- 3.1 vs. 7.1 +/- 0.7%), FL (7.6 +/- 5.4 vs. 1.7 +/- 1.2 mmol/mol lysine), and pentosidine (6.3 +/- 2.8 vs. 3.8 +/- 1.9 mumol/mol lysine). The disproportionate elevation of FL compared with HbA1 suggests a breakdown in the lens barrier to glucose in diabetes, whereas the increase in pentosidine is indicative of accelerated nonenzymatic browning of diabetic lens crystallins. CML levels were similar in the two groups (7.1 +/- 2.4 vs. 6.8 +/- 3.0 mmol/mol lysine), providing no evidence for increased oxidative stress in the diabetic cataract. Thus, although the modification of lens crystallins by autoxidation reactions was not increased in diabetes, the increase in glycation and nonenzymatic browning suggests that these processes may acclerate the development of cataracts in diabetic patients.
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PMID:Role of glycation in modification of lens crystallins in diabetic and nondiabetic senile cataracts. 190 46

The chaperone-like activity of alpha-crystallin is considered to play an important role in the maintenance of the transparency of the eye lens. However, in the case of aging and in diabetes, the chaperone function of alpha-crystallin is compromized, resulting in cataract formation. Several post-translational modifications, including non-enzymatic glycation, have been shown to affect the chaperone function of alpha-crystallin in aging and in diabetes. A variety of agents have been identified as the predominant sources for the formation of AGEs (advanced glycation end-products) in various tissues, including the lens. Nevertheless, glycation of alpha-crystallin with various sugars has resulted in divergent results. In the present in vitro study, we have investigated the effect of glucose, fructose, G6P (glucose 6-phosphate) and MGO (methylglyoxal), which represent the major classes of glycating agents, on the structure and chaperone function of alpha-crystallin. Modification of alpha-crystallin with all four agents resulted in the formation of glycated protein, increased AGE fluorescence, protein cross-linking and HMM (high-molecular-mass) aggregation. Interestingly, these glycation-related profiles were found to vary with different glycating agents. For instance, CML [N(epsilon)-(carboxymethyl)lysine] was the predominant AGE formed upon glycation of alpha-crystallin with these agents. Although fructose and MGO caused significant conformational changes, there were no significant structural perturbations with glucose and G6P. With the exception of MGO modification, glycation with other sugars resulted in decreased chaperone activity in aggregation assays. However, modification with all four sugars led to the loss of chaperone activity as assessed using an enzyme inactivation assay. Glycation-induced loss of alpha-crystallin chaperone activity was associated with decreased hydrophobicity. Furthermore, alpha-crystallin isolated from glycated TSP (total lens soluble protein) had also increased AGE fluorescence, CML formation and diminished chaperone activity. These results indicate the susceptibility of alpha-crystallin to non-enzymatic glycation by various sugars and their derivatives, whose levels are elevated in diabetes. We also describe the effects of glycation on the structure and chaperone-like activity of alpha-crystallin.
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PMID:Effect of glycation on alpha-crystallin structure and chaperone-like function. 1769 77

Total body irradiation combined with cyclophosphamide (TBI/CY) and busulphan combined with cyclophosphamide (BU/CY) are standard conditioning regimens in hematological stem cell transplantation for patients with myelogenous leukemia. This study was aimed to compare the therapeutic efficacy of TBI/CY and BU/CY as conditioning regiment for acute or chronic myelogenous leukemia. The Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, CNKI, CBM (Chinese Bio-medicine Database) had been searched for all relevant articles (1999-2007). Comparative studies were carried out on clinical therapeutic effects of TBI/CY and BU/CY including stem cell engraftment, relapse, complications, transplant-related mortality, and disease-free survival. A meta-analysis was performed using Review Manager 4.2 software and funnel plot regression was adopted to assess the publication bias. The results indicated that 2149 articles in English and 46 articles in Chinese were got, and finally 9 clinical trials with total 3039 patients have been assessed. No significantly difference was found in engraftment failure and transplant-related mortality resulting from TBI/CY and BU/CY conditioning regimens, but the incidence of veno-occlusion of liver and hemorrhagic cystitis obviously increased in BU/CY group after transplantation, the acute GVHD, interstitial pneumonia and cataract significantly increased in TBI/CY group. The relapse rate of AML in TBI/CY group was lower than that in BU/CY group, and the rate of long-term disease-free survival of AML patients in TBI/CY group also significantly lower than that in BU/CY group, but the relapse rate of CML in TBI/CY group after transplantation was obviously higher than that in BU/CY group, but there was no difference in longterm disease-free survival rate between the two conditioning regimens mentioned above. It is concluded that the meta-analysis confirms different effects of TBI/CY and BU/CY regimens on myelogenous leukemia transplantation. This result is useful for physicians to select treatment regimens.
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PMID:[Comparison of total body irradiation-cyclophosphamide versus busulphan-cyclophosphamide as conditioning regimens for myelogenous leukemia: a meta-analysis]. 1909 43