[Glycated albumin as a marker of glycemia in diabetes and its vascular complications]. / Glikowana albumina jako wskaznik glikemii w cukrzycy i jej naczyniowych powiklaniach.

Effective glycemic control is very important to prevent the onset and the progression of chronic complications in diabetic patients. It is known that glycation of various proteins is increased in diabetic patients compared with non-diabetics. Among these glycated proteins, glycated hemoglobin (HbA1c) is commonly used as a gold standard index of glycemic control in the clinical setting. However, it can be unreliable in conditions affecting the lifespan of erythrocytes (120 days) as well as in the clinical state in which glycemic control alleviates or deteriorates in a short period. By overcoming the shortcomings of HbA1c, glycated albumin (GA) has gained interest as a useful index for an intermediate glycation period (2 weeks) and pathogenic protein. After giving a brief overview of the key role of HbA1c as a long-term glycemic marker, this review focuses on (a) glycation of human albumin and its main properties, (b) methods of GA determination, (c) the recent clinical status of GA as a glycemic index in diabetic patients and its association with vascular complications. Finally, conditions with a possible inaccurate GA level are also mentioned.

Activities of neutrophil membrane-bound proteases in type 2 diabetic patients.

BACKGROUND AND AIMS: Hyperglycemia and oxidative stress in type 2 diabetes (T2DM) provoke neutrophil overstimulation and the release and/or translocation of proteases from granules to the cell surface. Although the expression of neutrophil membrane-bound elastase (MLE) is well documented, the presence of the membrane-bound form of cathepsin B (MCB) is unknown. The aim of our study was to evaluate the neutrophil MLE and MCB activities in T2DM patients and their associations with the metabolic and clinical parameters of the disease. METHODS: Neutrophils were obtained from 47 T2DM patients and 20 control subjects. The activities of MLE and MCB and the intracellular activities of the examined proteases (ILE and ICB, respectively) were measured using fluorometric substrates. Additionally, the percentage equivalents of the activities, namely, MLEtot/ILEtot and MCBtot/ICBtot, were calculated. The susceptibility to inhibitors of both forms of the studied proteases was also determined. RESULTS: A significant increase in the activities of MLE, MCB, ILE, and ICB was found in neutrophils from T2DM patients compared with the control group. The percentage equivalent (contribution of the total membrane-bound activities to the total intracellular activities) was also higher. A partial resistance of the membrane-bound forms toward their inhibitors was revealed. Higher activities of both the membrane-bound and the intracellular proteases were also observed in patients with poor glycemic and metabolic control. The differences between subgroups with different therapeutic schemes were also revealed. CONCLUSIONS: The pathophysiological implications of the neutrophil membrane-bound forms of leukocyte elastase and cathepsin B are of great importance in the development of T2DM and its complications.

Influence of aminoglycoside antibiotics on chicken cystatin binding to renal brush-border membranes.

OBJECTIVES: Drug-induced kidney injury is a serious adverse event which needs to be monitored during aminoglycoside therapy. Urine cystatin C is considered an early and sensitive marker of nephrotoxicity. Cystatin C, a low-molecular-weight serum protein, and basic drugs have a common transport system expressed in the apical membrane of renal proximal tubular cells. The aim of this study was to investigate whether aminoglycoside antibiotics influenced cystatin C binding to the renal brush-border membrane. METHODS: The binding study was performed using a rapid filtration technique and affinity column displacement method. KEY FINDINGS: Concentration-dependent inhibition of chicken cystatin binding to brush-border membranes by gentamicin was observed. The gentamicin interaction with brush-border membranes was of relatively low affinity (Ki = 32 µm) in comparison with the chicken cystatin affinity to the binding sites (Kd = 3.6 µm). Amikacin and gentamicin were only able to displace chicken cystatin from the chromatographic affinity column in concentrations several times higher than normally found in the tubular fluid during standard aminoglycoside therapy. CONCLUSION: Cystatin reabsorption in the proximal tubule cannot be significantly affected by aminoglycoside antibiotics because of their relatively low affinity to common binding sites on the brush-border membrane.

Binding of glycated ovocystatin to rat renal brush border membranes.

Glycated proteins are considered as one of the factors involved in the pathogenesis of diabetic complications, including nephropathy. These proteins are formed endogenously under conditions of hyperglycemia, as well as being provided with food containing sugars, which was subjected to high temperature. Examples are egg products. One of the proteins found in eggs in a relatively high concentration is chicken cystatin (ovocystatin). It is now believed that some proteins can passage the intestinal epithelium by transcytosis directly into the bloodstream. Thus, glycated protein present in food can be an additional source of glycotoxins. The aim of this study was to compare the affinity of native and glycated cystatin to the brush border membranes of rat kidney. Kinetic analysis was performed with surface plasmon resonance technique using sensor chip L1. Dissociation constants for native and glycated cystatin (Kd ) were 2.76 µmol/L and 3.82 µmol/L, respectively. The results of our study indicate that glycation only slightly affects binding of cystatin to brush border membranes. This suggests that glycated cystatin and other glycated proteins may also be efficiently taken up in the kidney proximal tubule. The observation may be important for understanding the mechanisms involved in the development of diabetic nephropathy.

Ischemia-modified albumin (IMA) is increased in patients with chronic hepatitis C infection and related to markers of oxidative stress and inflammation.

Inflammation and oxidative stress have been reported in patients with chronic hepatitis C (CHC) infection, but their influence on ischemia-modified albumin (IMA) levels and diabetes prevalence remains unknown. Sixty-three CHC patients, 28 with diabetes, and 40 healthy controls were enrolled in the study. Circulating levels of oxidative stress markers [Nε-(carboxymethyl)lysine- advanced glycation end products (CML-AGEs) and advanced oxidation protein products-(AOPPs)], pro-inflammatory cytokines (interleukin-6, and tumor necrosis factor α), and high-sensitivity C-reactive protein (hsCRP) were assessed. Compared with the controls, the CHC patients with diabetes showed a significant increase in plasma concentrations of IMA, AOPPs, interleukin-6 and hsCRP (P < 0.05). The values of IMA and hsCRP were more elevated in patients with diabetes than without diabetes (both P < 0.01). The positive relationships were found between hsCRP and presence of diabetes, IMA (both P < 0.01) and AOPP levels (P < 0.05). CML-AGEs did not show any significant correlation with IMA, markers of inflammation and presence of diabetes. In conclusion, we have documented significant elevation in plasma levels of IMA and AOPPs in CHC patients. In addition, circulating IMA was associated with inflammation markers and diabetes prevalence. This observation suggests a relationship between IMA and inflammation in CHC patients with diabetes, which may represent one of the mechanisms involved in the accelerated atherosclerosis in this population.

Picolinic acid in patients with chronic hepatitis C infection: a preliminary report.

Macrophage activation seems to be a feature of chronic liver diseases. Picolinic acid (PA) as a macrophage secondary signal causes the activation of interferon-gamma- (IFN-γ-) prime macrophage and triggers cytokine-driven inflammatory reactions. The rationale for seeking increased PA formation in chronic viral hepatitis is based on the involvement of activated macrophages in chronic viral hepatitis-associated inflammation. The aim of this study was to determine serum PA levels in patients with chronic hepatitis C infection, taking into account the presence of diabetes. We assessed PA and high-sensitivity C-reactive protein (hsCRP) as a marker of inflammation in 51 patients with chronic hepatitis C infection (CHC), both with and without diabetes and 40 controls. Compared with the controls, the patients with CHC showed a significant increase in plasma concentrations of PA and hsCRP (P < 0.01 and P < 0.05, resp.). The values of PA and hsCRP were more elevated in patients with diabetes than without diabetes (both P < 0.01). The positive relationships were between PA and hsCRP levels (P < 0.05) and the presence of diabetes (P < 0.001). We documented that significant elevation in serum PA levels is associated with diabetes prevalence and increased inflammatory response reflected in hsCRP levels in CHC patients.

[Serum chitotriosidase activity as a biomarker of pulmonary sarcoidosis]. / Aktywnosc chitotriozydazy jako biomarker plucnej postaci sarkoidozy.

Sarcoidosis is a multisystemic granulomatous disorder of unknown etiology, which is characterized by a variable clinical presentation and course. The diagnosis of this disease is usually supported by the three elements: compatible clinical and radiologic findings, tissue biopsy specimen that reveals noncaseating epithelioid granulomas and the absence of known granulomagenic agent. During the last years the new diagnostic methods have been discovered, but serum markers of the sarcoidosis are still under studying. Among the potential markers of sarcoidosis, a recently proposed indicator is chitotriosidase, a chitinase produced by chronically activated macrophages. The review of the literature showed that chitotriosidase activity is only a surrogate biomarker to confirm diagnosis, but is a useful marker for disease activity monitoring and prognosis. The correlation with the radiological stages of disease suggest that determination of chitotriosidase activity could decrease the number of X-ray examination.

[Urinary cystatin C as a biomarker of renal tubular injury]. / Moczowa cystatyna C jako biomarker uszkodzenia kanalików nerkowych.

Cystatin C (cysC) is an endogenous cysteine peptidase (proteinase) inhibitor that has been intensively investigated as a biomarker of kidney function for many years. It is freely filtered at the kidney glomerulus because of its small size and lack of cysC binding protein. A very small amount of cysC appears in the urine because of its total reabsorption in the proximal tubule and lack of secretion. Since 1985 cystatin C has been studied mainly in serum/plasma as an alternative biomarker to serum creatinine to estimate GFR. In this review we present the recent discoveries concerning urinary cystatin C determination as a tubular injury biomarker.

Advanced oxidation protein products and inflammatory markers in liver cirrhosis: a comparison between alcohol-related and HCV-related cirrhosis.

Advanced oxidation protein products (AOPPs) are protein markers of oxidative stress with pro-inflammatory properties that accumulated in liver cirrhosis. In the present study, we investigated the association between chronic inflammatory response triggered by AOPPs and the severity of liver disease as assessed by the Child-Pugh score. Plasma concentrations of AOPPs and inflammatory markers such as C-reactive protein, tumor necrosis factor-α, and interleukin-6 were measured in 41 patients with HCV-related cirrhosis, 43 patients with alcohol-related liver cirrhosis (ALC), and in 30 age and sex matched controls. In comparison with controls, AOPPs were increased in HCV-related compensated (Child-Pugh A) and decompensated (Child-Pugh B-C) cirrhosis and in alcohol-related compensated cirrhosis. AOPPs level positively correlated with Child-Pugh score in alcohol-related cirrhosis but not in HCV-related cirrhosis and the correlation with the indices of chronic inflammation was stronger in ALC. In turn, AOPPs in HCV-related cirrhosis was related to inflammation to a lesser extent, but a significant correlation with antioxidant defense could be noted. In summary, liver cirrhosis was associated with increased formation of AOPPs, which differed between alcohol-related and HCV-related cirrhosis with respect to the relationship between AOPPs and antioxidant defense, stage of liver cirrhosis, and inflammatory response. The significant correlation between AOPPs accumulation and indices of chronic inflammation, more specifically TNF-α, suggests that oxidative stress may be a mediator of chronic inflammatory state in the early stage of alcohol-related cirrhosis.

Comparison of the usefulness of plasma levels of oxidatively modified forms of albumin in estimating kidney dysfunction in diabetic patients.

PURPOSE: Advanced oxidation protein products (AOPP) and ischemia-modified albumin (IMA) are forms of oxidatidatively modified albumin and have recently been investigated as indicators of oxidative stress. They are increased in different disorders, including diabetes mellitus, as a result of hyperglycaemia, oxidative stress and hypoxia. The usefulness of the plasma levels of these two parameters in estimating kidney dysfunction in type 2 diabetic patients (T2DM) was compared in this study. METHODS: Plasma levels of AOPP and IMA were determined spectrophotometrically in 218 individuals, 153 patients with T2DM and 65 healthy people.. The urinary albumin/creatinine ratio (UACR) was used as the reference to define the stage of kidney dysfunction by the assessment of the degree of albuminuria. RESULTS: Receiver Operating Characteristic (ROC) curve analysis, likelihood ratio (LR), and Youden's index (J) revealed that AOPP and IMA had acceptable sensitivities and specificities in individuals with different degrees of albuminuria; however, AOPP had higher values of the area under the curve (AUC: 0.934) than IMA, as well as 100% sensitivity and 77.01% specificity for distinguishing patients with micro- and macroalbuminuria. CONCLUSIONS: Both AOPP and IMA may be helpful clinical markers for estimating kidney dysfunction, but AOPP is better able to identify diabetic patients with nephropathy. We suggest that AOPP is almost ideal for discriminating between T2DM patients with micro- and macroalbuminuria.

Elevated advanced oxidation protein products levels in patients with liver cirrhosis.

Serum concentrations of advanced oxidation protein products (AOPPs) and glycation end products (AGEs) were assessed with respect to functional compromise of liver, as determined by the Child-Pugh and MELD scores. Patients with decompensated liver cirrhosis (Child-Pugh B and C) exhibited significantly higher serum concentrations of AOPPs than both patients with compensated liver cirrhosis (Child-Pugh A) and controls. The levels of plasma AGEs in all liver cirrhotic patients were higher when compared with those with the controls and this difference was statistically significant. Plasma total antioxidant status of the patients was significantly lower than that of controls. Significant positive correlations between AOPPs level and the MELD score and between the oxidative stress index and the MELD score were found in all patients with liver cirrhosis. Altered AOPPs levels in decompensated patients may influence the potency of oxidative stress and the progression of liver disease.

[Serum activity of chitotriosidase, lysozyme and cathepsin H in patients with lung cancer and patients with inflammatory exudate (preliminary report)]. / Aktywnosc chitotriozydazy oraz lizozymu i katepsyny H w surowicy chorych na raka pluca i chorych z wysiekiem zapalnym (doniesienie wstepne).

UNLABELLED: Lung cancer remains the leading cause of cancer death over the world. Although new diagnostic methods have been discovered, new biomarkers of the cancer are still under studying. A human chitinolytic enzyme called chitotriosidase hydrolyzes chitin and chitotrioside substrates. It is specifically expressed by activating macrophages and seems to play a role in the defense against chitinous human pathogens. Recently it has been shown that chitotriosidase may also attend to the inflammatory process. The aim of the study was to determine chitotriosidase activity in serum of patients with lung cancer and patients with inflammatory exudate. We studied the usefulness of the above parameter determination in differentiation between lung cancer and inflammation. In addition, serum activity of lysozyme and cathepsin H was determined. MATERIALS AND METHODS: The study included 17 patients with inflammatory pleural exudate--group 1., 40 lung cancer patients with malignant pleural effusion--group 2. and 37 healthy subjects. All the patients of group 2. were divided into 2 subgroups: 2A without metastases (n = 23) and 2B with metastases (n = 17). Chitotriosidase and cathepsin H activity was determined in serum by a fluorometric methods. Serum lysozyme activity was measured by turbidimetric method with Micrococcus luteus as substrate. RESULTS: We observed an increase of the chitotriosidase activity in serum patients of both studied group in comparison with the control. The activity of the chitotriosidase in lung cancer patients was significantly higher than in the control (36.7 vs 68.1 nmol/ml/h; p < 0.01). There were no significant differences in serum lysozyme and cathepsin H activity in patients in comparison to healthy subjects. CONCLUSION: The results suggest that activity of the chitotriosidase can not be used to differentiation between inflammation and cancer in lung.

[Oxidative stress and endothelium dysfunction in diabetes mellitus type 2]. / Stres oksydacyjny a dysfunkcja sródblonka w cukrzycy typu 2.

UNLABELLED: The aim of our study was to estimate the influence of oxidative stress on the function of vascular endothelium in diabetes mellitus type 2, through the measurement plasma levels of chosen parameters reflecting these disturbances--concentration of advanced oxidation protein products (AOPP) and activity of gamma glutamyltransferase (GGT) and N-acetyl-beta-glucosaminidase (NAG). MATERIALS AND METHODS: 73 patients with type 2 diabetes mellitus and 23 healthy people, which made up the control group were examined. In plasma of these subjects concentration of AOPP by spectrophotometric method with the use of potassium iodide; activity of GGT by spectrophotometric method and NAG activity by spectrofluorymetric method were determined. RESULTS: The plasma levels of all examined parameters were significantly higher in diabetic patients than in healthy people. We observed increase of these parameters in groups of patients clustered on the basis of disease duration, glicemic state of diabetes and vascular area occupied by diabetic complication. The most significant changes in AOPP concentration were observed. There was statistically significant correlation between AOPP and GGT, however there was no any direct connection of these two parameters with NAG activity. CONCLUSIONS: We showed significantly increase in the AOPP concentration and activities of GGT and NAG in plasma of patients with type 2 diabetes, which was induced by hyperglycemia and oxidative stress connected with this disease. The growth of examined parameters had no direct connection with each other, however was connected with chronic nature of this disease, glycemic decomposition and vascular area occupied by diabetic complication.

[Fluorescence of age in serum in detecting liver cirrhosis and hepatocellular carcinoma among patients with anti-HCV antibodies]. / Fluorescencja koncowych produktów glikacji (AGE) surowicy krwi w wykrywaniu marskosci i raka watroby u osób z przeciwcialami anty-HCV.

OBJECTIVE: To evaluate usefulness of total fluorescence of advanced glycation end products (AGE) and haptoglobin (Hp) measurement in human serum as parameters in liver cirrhosis and hepatocellular carcinoma development among patients with anti-HCV antibodies. MATERIALS AND METHODS: 43 patients (20 women and 23 men) with chronic hepatitis HCV were examined (14 individuals with liver cirrhosis and 9 with primary liver cancer). The control group numbers 20. As reflection of AGE concentration, total fluorescence in serum samples was measured with spectrofluorimetric method and haptoglobin with microplate guaiacol test. RESULTS: We affirmed that total fluorescence in examined groups was higher than in healthy subjects, but increase was not statistically significant. Fluorescence of AGE in serum from patients with hepatocellular carcinoma was lower in comparison to patients with cirrhosis and anti-HCV carriers. Haptoglobin was significantly decreased in serum of cirrhosis patients as compared to HCV carriers of patients with hepatocellular carcinoma (p < 0.001). CONCLUSIONS: The measurement of total fluorescence AGE is not differentiating for liver cirrhosis and hepatocellular carcinoma among anty-HCV carriers. We confirmed that haptoglobin, parameter included in fibrotest, is very useful, in detecting liver cirrhosis.

Ischemia-modified albumin level in type 2 diabetes mellitus - Preliminary report.

AIM: The main goal of the present study was the evaluation of ischemia-modified albumin (IMA) in patients with type 2 diabetes mellitus and estimation of its connection with vascular complications, glycemic control, hypertension, dyslipidemia and obesity. METHODS: In 76 diabetic patients and 25 control subjects, a plasma level of IMA by manually performed, spectrophotometric Co(II)-albumin binding assay was determined. Other parameters such as glucose, fructosamine, HbA_{1c}, total cholesterol and its fractions (HDL, LDL), triglicerydes were estimated by routine methods. RESULTS: Diabetic patients had significantly higher level of IMA in comparison with control subjects. There were not significant differences between groups with various states of vascular complications although the lowest concentration of IMA was observed in patients with microangiopathy. Patients with poor glycemic control had higher IMA level in comparison with these with good glycemic control. Significant correlation was observed between IMA and HbA_{1c}. Among the risk factors, only blood pressure and LDL showed a weak relationship with IMA level. CONCLUSIONS: Our results revealed, for the first time, higher level of IMA in diabetic patients which confirms that it may be of non-cardiac origin. We can suggest that the albumin molecule in plasma of diabetic patients is modified in the chronic hypoxia conditions provoked mainly by hyperglycemia and oxidative stress in diabetes.

Plasma glycooxidation protein products in type 2 diabetic patients with nephropathy.

BACKGROUND: In diabetes mellitus, hyperglycaemia accelerates non-enzymatic glycation and oxidative stress leading to damage of macromolecules, among others proteins. This manifests in the increased levels of advanced glycation end products (AGE) and advanced oxidation protein products (AOPP). OBJECTIVES: To assess the plasma levels of AGE and AOPP in the patients with type 2 diabetes mellitus (T2DM) and to estimate its relation and connection with the degree of nephropathy. MATERIAL AND METHODS: In 121 diabetic patients and 22 healthy people plasma levels of AGE and AOPP were determined with fluorimetric and spectrophotometric methods, respectively. To estimate nephropathy stage, albumin/creatinine ratio was calculated on the basis of albumin and creatinine concentrations in early morning urine samples. RESULTS: Diabetic patients had significantly higher levels of AGE and AOPP in comparison to healthy people. Both parameters were increasing progressively from normoalbuminuria, through microalbuminuria to macroalbuminuria. Statistically, the most significant differences were observed in AOPP concentration between separated groups. AGE fluorescence was significantly different on the same low, statistical level between patients with normoalbuminuria when compared to those with micro- and macroalbuminuria. Plasma AGE correlated significantly with urinary albumin/creatinine ratio whereas AOPP correlated with plasma creatinine level. CONCLUSIONS: The connection between plasma levels of both glycooxidation protein products-AGE and AOPP with nephropathy severity, measured by the degree of albuminuria, in T2DM patients was observed. We can suggest that the AOPP better reflect the progression of kidney damage than AGE in examined diabetic patients.

[Ischemia modified albumin--specific marker in cardiological diagnostics?]. / Albumina modyfikowana niedokrwieniem--specyficzny marker w diagnostyce kardiologicznej?

Ischemia modified albumin (IMA) is a new biological marker for early identification of chest pain and ruling out myocardial infarction among patients with acute syndromes submitting to emergency department. Recently IMA has been investigated in the light of other cardiac markers (cTnT, CK-MBmas, NT-proBNP) in various states of ischemia (acute coronary syndromes, after percutaneous coronary intervention, in coronary vasospasm). Ischemia modified albumin levels were elevated in these states what suggests myocardial ischemia. However decrease in IMA concentration after exercise-induced skeletal muscle ischemia still remains unclear. Increased IMA concentration in patients with acute ischemic stroke and exposed to trauma limits its ability for detection myocardial ischemia. Specificity of IMA measurement is limited also in patients with peripheral vascular disease, systemic sclerosis, diabetes, end stage renal disease, pulmonary embolism and other pathological states with accompanying oxidative stress.

[Molecular aspects of aminoglycoside nephrotoxicity]. / Molekularne aspekty nefrotoksycznosci antybiotyków aminoglikozydowych.

Aminoglycosides are potent bactericidal antibiotics particularly active against aerobic Gram-negative bacteria. This review focuses on the recent concept of a molecular understanding of aminoglycoside-induced nephrotoxicity. As receptor-mediated endocytosis plays an important role in the accumulation of aminoglycosides in renal proximal tubules, the biochemical properties of the two main receptors, megalin and cubilin, involved in this process are described. Literature data on megalin and acidic phospholipids as potential targets for preventing aminoglycoside-induced nephrotoxicity are also presented.

AOPP and its relations with selected markers of oxidative/antioxidative system in type 2 diabetes mellitus.

BACKGROUND: The aim of this study was to evaluate the selected components of the oxidative/antioxidative system in T2DM; estimation of relationships between them; search for the more expressive one and examine their alterations in angiopathy and obesity. METHODS: In 94 diabetic patients and 36 healthy people, plasma levels of TRAP, as a marker of antioxidative defence, as well as concentrations of CO, SH, and NH(2) groups and AOPP, as markers of oxidative protein damage (OPD) were determined. RESULTS: Patients had significantly lower levels of TRAP and SH groups, as well as higher NH(2), CO and AOPP in comparison to control. Significant correlation was observed between TRAP and SH groups and AOPP as well as between AOPP and SH and CO groups. Concentration of AOPP was significantly higher in the macroangiopathy and obese subgroups. CONCLUSIONS: Our results support the idea that diabetes mellitus is a complex metabolic disorder with oxidant/antioxidant defence disturbances. Among the studied parameters AOPP showed the most expressive raise in plasma of diabetic patients and significant differences between their subgroups with vascular complications and overweight. We can conclude that AOPP seems to be considered as a useful marker to estimate the degree of OPD in diabetic patients.

Characterization of chicken cystatin binding to rat renal brush-border membranes.

Chicken cystatin, a homologue of human cystatin C, like other low-molecular-weight proteins is metabolized by renal proximal tubule cells. However, the precise mechanism(s) of this process has not been elucidated yet. To characterize chicken cystatin binding to renal brush-border membranes, the incubation of fluorescein labelled protein with rat cortical homogenate was performed. Saturation-dependent and reversible binding with low affinity (K(d)=3.67-4.07 microM) and high capacity (B(max)=2.32-2.79 nmol/mg) was observed. Bovine albumin was the most potent competitor (K(i)=0.7 microM) among other megalin/cubilin ligands tested. The presence of Ca(+2) ions was necessary to effective cystatin binding by brush-border membranes. Obtained data strongly support the hypothesis that chicken cystatin is a novel ligand for megalin/cubilin receptors tandem on proximal tubular cells.