Carnosine prevents apoptosis of glomerular cells and podocyte loss in STZ diabetic rats.

BACKGROUND/AIMS: We identified carnosinase-1 (CN-1) as risk-factor for diabetic nephropathy (DN). Carnosine, the substrate for CN-1, supposedly is a protective factor regarding diabetic complications. In this study, we hypothesized that carnosine administration to diabetic rats might protect the kidneys from glomerular apoptosis and podocyte loss. METHODS: We examined the effect of oral L-carnosine administration (1g/kg BW per day) on apoptosis, podocyte loss, oxidative stress, AGEs and hexosamine pathway in kidneys of streptozotocin-induced diabetic Wistar rats after 3 months of diabetes and treatment. RESULTS: Hyperglycemia significantly reduced endogenous kidney carnosine levels. In parallel, podocyte numbers significantly decreased (-21% compared to non-diabetics, p<0.05), apoptotic glomerular cells numbers increased (32%, compared to non-diabetic, p<0.05) and protein levels of bax and cytochrome c increased (175% and 117%). Carnosine treatment restored carnosine kidney levels, prevented podocytes loss (+23% compared to diabetic, p<0.05), restrained glomerular apoptosis (-34% compared to diabetic; p<0.05) and reduced expression of bax and cytochrome c (-63% and -54% compared to diabetics, both p<0.05). In kidneys of all diabetic animals, levels of ROS, AGEs and GlcNAc-modified proteins were increased. CONCLUSION: By inhibition of pro-apoptotic signaling and independent of biochemical abnormalities, carnosine protects diabetic rat kidneys from apoptosis and podocyte loss.

Oral carnosine supplementation prevents vascular damage in experimental diabetic retinopathy.

BACKGROUNDS/AIMS: Pericyte loss, vasoregression and neuroglial activation are characteristic changes in incipient diabetic retinopathy. In this study, the effect of the antioxidant and antiglycating dipeptide carnosine was studied on the development of experimental diabetic retinopathy. MATERIALS/METHODS: STZ-induced diabetic Wistar rats were orally treated with carnosine (1g/kg body weight/day). Retinal vascular damage was assessed by quantitative morphometry. Retinal protein extracts were analyzed for markers of oxidative stress, AGE-formation, activation of the hexosamine pathway and changes in the expression of Ang-2, VEGF and heat shock proteins Hsp27 and HO-1. Glial cell activation was analyzed using Western blot analysis and immunofluorescence of GFAP expression and retinal neuronal damage was histologically examined. RESULTS: Oral carnosine treatment prevented retinal vascular damage after 6 months of experimental hyperglycemia. The protection was not caused by ROS- or AGE-inhibition, but associated with a significant induction of Hsp27 in activated glial cells and normalization of increased Ang-2 levels in diabetic retinas. A significant reduction of photoreceptors in retinas of carnosine treated animals was noted. CONCLUSION: Oral carnosine treatment protects retinal capillary cells in experimental diabetic retinopathy, independent of its biochemical function. The vasoprotective effect of carnosine might be mediated by the induction of protective Hsp27 in activated glial cells and normalization of hyperglycemia-induced Ang-2.

Comparison of two different methods for CA19-9 antigen determination.

BACKGROUND: This study was designed to investigate the clinical performance of the Access GI Monitor (Beckman Coulter) on the UniCel DxI 800, a method for CA19-9 antigen determination, and to compare with CA19-9 assay on the AxSYM system (Abbott). METHODS: 1,063 serum samples from unselected patients with different underlying diagnoses were tested with both methods. Passing-Bablok regression analysis and Bland Altman analysis was performed. In addition, using ROC analysis, the distribution of Access GI Monitor and AxSYM CA19-9 antigen levels was tested in patients with pancreatic cancer (n = 50), acute inflammatory disease (n = 20), and with chronic inflammation of the pancreatic gland (n = 18). Furthermore, four patients with pancreatic cancer were monitored individually in their courses of the disease (before, during, and after therapeutic procedures) to compare their CA19-9 values with regard to inter-method concordance. RESULTS: Passing-Bablok analysis showed a systematic difference with R = 0.93, slope 0.75, and intercept -1.0. Bland Altman analysis showed a wide scatter of relative differences between both methods, especially in the low end measuring range. In the selected group of patients with pancreatic diseases the analysis of concordance revealed 95.5 % agreement between both methods with a comparable area under the ROC curves (0.73 vs. 0.76). A clear concordance was found for all four selected patients. CONCLUSIONS: Although we found significant systematic measuring variations in the global analysis, the two different automated methods for the quantitative determination of CA19-9 antigen were comparable with respect to their clinical accuracy and applicability to support decision making in the management of pancreatic cancer.

L-carnosine, a substrate of carnosinase-1, influences glucose metabolism.

OBJECTIVE: Carnosinase 1 (CN1) is a secreted dipeptidase that hydrolyzes L-carnosine. Recently, we have identified an allelic variant of human CN1 (hCN1) that results in increased enzyme activity and is associated with susceptibility for diabetic nephropathy in human diabetic patients. We therefore hypothesized that L-carnosine in the serum represents a critical protective factor in diabetic patients. RESEARCH DESIGN AND METHODS: L-carnosine serum levels were manipulated in db/db mice, a model of type 2 diabetes. In a transgenic approach, hCN1 cDNA was expressed under the control of a liver-specific promoter in db/db mice, mimicking the expression pattern of hCN1 in humans. RESULTS: Fasting plasma glucose as well as A1C levels rose significantly earlier and remained higher in transgenic animals throughout life. Body weights were reduced as a result of significant glucosuria. In an opposite approach, nontransgenic db/db mice were supplemented with L-carnosine. In these latter mice, diabetes manifested significantly later and milder. In agreement with the above data, serum fasting insulin levels were low in the transgenic mice and elevated by L-carnosine feeding. Insulin resistance and insulin secretion were not significantly affected by L-carnosine serum levels. Instead, a significant correlation of L-carnosine levels with beta-cell mass was observed. CONCLUSIONS: hCN1-dependent susceptibility to diabetic nephropathy may at least in part be mediated by altered glucose metabolism in type 2 diabetic patients.

C-reactive protein as predictor of death in end-stage diabetic nephropathy: role of peripheral arterial disease.

BACKGROUND: Patients with diabetes type 2 receiving dialysis therapy have a poor survival prognosis, mainly due to cardiovascular events. Increased C-reactive protein (CRP) levels, important in atherosclerosis, are associated with an increased risk for cardiovascular events. However, to date no study has shown the predictive value of CRP in relation to peripheral arterial disease stage. METHODS: We enrolled all 445 prevalent patients with diabetic nephropathy receiving maintenance hemodialysis in 30 centers in Southern Germany from August 1999 to January 2000 for prospective study until December 2003. At inclusion, CRP and a complete clinical phenotype, including peripheral arterial disease Fontaine Stage were determined. The primary end point was all-cause mortality. RESULTS: A total of 305 (68.5%) patients died. An increased log CRP at study inclusion was significantly associated with an increase in hazard ratio (HR) by multivariate Cox regression for all-cause (HR = 1.5, P= 0.002) and cardiac death (HR = 1.76, P= 0.02) in the entire collective. This result was applicable only to patients with peripheral arterial disease Fontaine stage IV (N= 190, multivariate HR = 1.75 for all-cause mortality, P= 0.006). Possibly due to inadequate power, we observed only an insignificant trend for CRP as predictor of all-cause death in patients without peripheral arterial disease or with less severe forms of peripheral arterial disease (HR = 1.36, P= 0.08). CONCLUSION: In contrast to patients with peripheral arterial disease stage IV, patients with less severe atherosclerosis and elevated CRP are, if any, at less risk for cardiovascular mortality, possibly due to the difference in extent of affected vasculature and thus activated platelets and coagulation. Before judging the predictive value of CRP for mortality, peripheral vessel status should be determined.

RANTES gene polymorphisms predict all-cause and cardiac mortality in type 2 diabetes mellitus hemodialysis patients.

INTRODUCTION: Patients with type 2 diabetes (DM2) and end stage renal disease (ESRD) have a dismal survival prognosis, mainly due to cardiovascular events. There is sparse data on genetic predictors. Chemokines and their receptors are important in regulating leukocyte influx and activation in atherosclerosis, and functional polymorphisms in the respective genes are associated with cardiovascular disease risk. METHODS: We enrolled 225 prevalent Caucasian DM2 patients receiving maintenance hemodialysis in 30 centres in Southern Germany (time from dialysis initiation <2.0 years) from August 1999 to January 2000 for prospective study until December 2003. The CX3CR1 T280M, and MCP-1 -2518 and RANTES -403 and -28 promoter and intronic In1.1T/C polymorphisms were assessed by real-time PCR. Primary end point was all-cause mortality (ACM). RESULTS: Patients carrying the RANTES -403A or In1.1C allele had a significantly higher ACM risk (multivariate hazard ratio for -403A, dominant model=1.81 [95% CI: 1.22-2.67], p=0.003), mainly due to cardiac events. Similar data were obtained by haplotype analysis. The other SNPs showed no effect on survival. DISCUSSION: In DM2 patients with ESRD, ACM due to cardiac events is associated with RANTES gene variants that are known to alter the expression of this chemokine important in atherosclerosis. Further study of the role of chemokine and chemokine receptor gene variation in determining vascular end points is needed.