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Glycation of nail proteins: from basic biochemical findings to a representative marker for diabetic glycation-associated target organ damage.

Kishabongo AS, Katchunga P, Van Aken EH, Speeckaert R, Lagniau S, Coopman R, Speeckaert MM, Delanghe JR - PLoS ONE (2015)

Bottom Line: A significant higher amount of glycated eye lens proteins was found in diabetes mellitus patients (mean: 3.80 ± 1.57 μmol/g eye lens) in comparison with nondiabetics (mean: 3.35 ± 1.34 μmol/g eye lens) (P<0.05).The concentration of glycated eye lens proteins and the HbA1c level were found to be predictors of the concentration of glycated nail proteins.Glycation of nail proteins can be regarded as a representative marker for diabetic glycation-associated target organ damage.

View Article: PubMed Central - PubMed

Affiliation: Department of Laboratory Medicine, Catholic University of Bukavu, Bukavu, Democratic Republic of the Congo.

ABSTRACT

Background: Although assessment of glycated nail proteins may be a useful marker for monitoring of diabetes, their nature and formation are still poorly understood. Besides a detailed anatomical analysis of keratin glycation, the usefulness of glycated nail protein assessment for monitoring diabetic complications was investigated.

Methods: 216 patients (94 males, 122 females; mean age ± standard deviation: 75.0 ± 8.7 years) were enrolled. Glycation of nail and eye lens proteins was assessed using a photometric nitroblue tetrazolium-based assay. Following chromatographic separation of extracted nail proteins, binding and nonbinding fractions were analyzed using one-dimensional gel electrophoresis. Using a hand piece containing a latch-type-bur, a meticulous cutting of the nail plate into superficial and deep layers was performed, followed by a differential analysis of fructosamine.

Results: Using SDS PAGE, four and two bands were identified among the nonglycated and glycated nail fraction respectively. Significantly lower fructosamine concentrations were found in the superficial nail layer (mean: 2.16 ± 1.37 μmol/g nails) in comparison with the deep layer (mean: 4.36 ± 2.55 μmol/g nails) (P<0.05). A significant higher amount of glycated eye lens proteins was found in diabetes mellitus patients (mean: 3.80 ± 1.57 μmol/g eye lens) in comparison with nondiabetics (mean: 3.35 ± 1.34 μmol/g eye lens) (P<0.05). A marked correlation was found between glycated nail and glycated eye lens proteins [y (glycated nail proteins) = 0.39 + 0.99 x (eye lens glycated proteins); r2 = 0.58, P<0.001]. The concentration of glycated eye lens proteins and the HbA1c level were found to be predictors of the concentration of glycated nail proteins.

Conclusions: Glycation of nail proteins takes place in the deep layer of finger nails, which is in close contact with blood vessels and interstitial fluid. Glycation of nail proteins can be regarded as a representative marker for diabetic glycation-associated target organ damage.

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Illustration of the diffusion process of glucose from the deep part to the superficial part of the nail, explaining the differential concentration of glycated proteins in both layers of the human finger nail.
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pone.0120112.g005: Illustration of the diffusion process of glucose from the deep part to the superficial part of the nail, explaining the differential concentration of glycated proteins in both layers of the human finger nail.

Mentions: In spite of the great interest of protein glycation in the diagnosis of diabetes mellitus, little attention has been paid to the glycation process occurring in nail tissues. The analysis of glycated proteins from deep and superficial layers of the nail contributes to the understanding of glycated keratin formation. The significant higher fructosamine concentration in the deep layer than in the superficial layer of the human finger nail suggests that keratin glycation occurs in the deep layer of nails. The human nail structure is an appendage of the integument and forms a continuous and integrated structure with the skin, consisting of a nail bed, a nail matrix and a nail plate. The nail bed is a deep membrane with nerves, lymph vessels and blood vessels [26]. As nail proteins are exposed to glucose, originating from the blood and the extracellular fluid through its nail bed part, glycation of nail keratins can take place. Because of the complex morphological structure of nails (abundance of disulfide crosslinks), the diffusion of glucose from the deep part to the superficial part occurs very slow, explaining the differential concentration of glycated proteins in both layers of the human finger nail (Fig. 5). For that reason, the concentration of glycated proteins in the deep layer of the human finger nail is probably a better marker for diabetes mellitus and its complications in comparison with the superficial layer.


Glycation of nail proteins: from basic biochemical findings to a representative marker for diabetic glycation-associated target organ damage.

Kishabongo AS, Katchunga P, Van Aken EH, Speeckaert R, Lagniau S, Coopman R, Speeckaert MM, Delanghe JR - PLoS ONE (2015)

Illustration of the diffusion process of glucose from the deep part to the superficial part of the nail, explaining the differential concentration of glycated proteins in both layers of the human finger nail.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4363324&req=5

pone.0120112.g005: Illustration of the diffusion process of glucose from the deep part to the superficial part of the nail, explaining the differential concentration of glycated proteins in both layers of the human finger nail.
Mentions: In spite of the great interest of protein glycation in the diagnosis of diabetes mellitus, little attention has been paid to the glycation process occurring in nail tissues. The analysis of glycated proteins from deep and superficial layers of the nail contributes to the understanding of glycated keratin formation. The significant higher fructosamine concentration in the deep layer than in the superficial layer of the human finger nail suggests that keratin glycation occurs in the deep layer of nails. The human nail structure is an appendage of the integument and forms a continuous and integrated structure with the skin, consisting of a nail bed, a nail matrix and a nail plate. The nail bed is a deep membrane with nerves, lymph vessels and blood vessels [26]. As nail proteins are exposed to glucose, originating from the blood and the extracellular fluid through its nail bed part, glycation of nail keratins can take place. Because of the complex morphological structure of nails (abundance of disulfide crosslinks), the diffusion of glucose from the deep part to the superficial part occurs very slow, explaining the differential concentration of glycated proteins in both layers of the human finger nail (Fig. 5). For that reason, the concentration of glycated proteins in the deep layer of the human finger nail is probably a better marker for diabetes mellitus and its complications in comparison with the superficial layer.

Bottom Line: A significant higher amount of glycated eye lens proteins was found in diabetes mellitus patients (mean: 3.80 ± 1.57 μmol/g eye lens) in comparison with nondiabetics (mean: 3.35 ± 1.34 μmol/g eye lens) (P<0.05).The concentration of glycated eye lens proteins and the HbA1c level were found to be predictors of the concentration of glycated nail proteins.Glycation of nail proteins can be regarded as a representative marker for diabetic glycation-associated target organ damage.

View Article: PubMed Central - PubMed

Affiliation: Department of Laboratory Medicine, Catholic University of Bukavu, Bukavu, Democratic Republic of the Congo.

ABSTRACT

Background: Although assessment of glycated nail proteins may be a useful marker for monitoring of diabetes, their nature and formation are still poorly understood. Besides a detailed anatomical analysis of keratin glycation, the usefulness of glycated nail protein assessment for monitoring diabetic complications was investigated.

Methods: 216 patients (94 males, 122 females; mean age ± standard deviation: 75.0 ± 8.7 years) were enrolled. Glycation of nail and eye lens proteins was assessed using a photometric nitroblue tetrazolium-based assay. Following chromatographic separation of extracted nail proteins, binding and nonbinding fractions were analyzed using one-dimensional gel electrophoresis. Using a hand piece containing a latch-type-bur, a meticulous cutting of the nail plate into superficial and deep layers was performed, followed by a differential analysis of fructosamine.

Results: Using SDS PAGE, four and two bands were identified among the nonglycated and glycated nail fraction respectively. Significantly lower fructosamine concentrations were found in the superficial nail layer (mean: 2.16 ± 1.37 μmol/g nails) in comparison with the deep layer (mean: 4.36 ± 2.55 μmol/g nails) (P<0.05). A significant higher amount of glycated eye lens proteins was found in diabetes mellitus patients (mean: 3.80 ± 1.57 μmol/g eye lens) in comparison with nondiabetics (mean: 3.35 ± 1.34 μmol/g eye lens) (P<0.05). A marked correlation was found between glycated nail and glycated eye lens proteins [y (glycated nail proteins) = 0.39 + 0.99 x (eye lens glycated proteins); r2 = 0.58, P<0.001]. The concentration of glycated eye lens proteins and the HbA1c level were found to be predictors of the concentration of glycated nail proteins.

Conclusions: Glycation of nail proteins takes place in the deep layer of finger nails, which is in close contact with blood vessels and interstitial fluid. Glycation of nail proteins can be regarded as a representative marker for diabetic glycation-associated target organ damage.

Show MeSH
Related in: MedlinePlus