Protein oxidation in Type 2 diabetic patients on hemodialysis

Fluorescent advanced glycation end products in type 2 diabetes and its association with diabetes duration, hemoglobin A1c, and diabetic complications

Background

Fluorescent advanced glycation end products (fAGEs) are generated through the Maillard reaction between reducing sugars and amino compounds. fAGEs accumulation in human bodies have been confirmed to be related to many chronic diseases. To date, the correlations between serum fAGEs levels and clinical parameters or carotid intima media thickness (CIMT) in patients with T2DM remain unclear. Thus, this study aimed to investigate the relationship between serum AGEs levels and clinical parameters or CIMT in patients with T2DM.

Method

A total of 131 patients with diabetes and 30 healthy controls were enrolled. Patients were divided into three groups according to diabetes duration, including ≤5, 5-10, and ≥10 years. Serum fAGEs, protein oxidation products, clinical parameters, and CIMT were determined.

Results

The result showed that levels of fAGEs and protein oxidation products increased with the increasing duration of diabetics. Pearson correlation coefficients of fAGEs versus hemoglobin A1c (HbA1c) were >0.5 in patients with diabetes duration ≥10 years. A continued increase in fAGEs might cause the increase of HbA1c, urinary albumin/creatinine ratio (UACR) and CIMT in patients with T2DM.

Conclusion

Our study suggested that levels of fAGEs could be considered as an indicator for duration of diabetics and carotid atherosclerosis. Diabetes duration and smoking might have a synergistic effect on the increment of fAGEs levels, as evidence by the results of correlation analysis in patients with long-duration diabetics (≥10 years) and smoking. The determination of fAGEs might be helpful to advance our knowledge on the overall risk of complications in patients with T2DM.

Plasma thiol/disulphide homeostasis changes in patients with relapsing-remitting multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) is a neuroinflammatory disease and inflammation and oxidative stress play important roles in its pathology. Thiol/disulphide homeostasis (TDH) is a special oxidative stress biomarker that has been found to be affected in several disorders including MS. There is no study demonstrating the effects of attack status of the relapsing-remitting multiple sclerosis (RRMS) patients on TDH levels. Our aim was to determine TDH levels in three different periods of RRMS patients and healthy individuals.

METHODS

The study was carried out in 29 patients with RRMS without a prior attack in the last twelve months (MS Control), 21 RRMS patients having a clinical acute attack within the last week (MS relapse), 12 of 21 MS relapse patients one month after the onset of attack and following 1000 mg methylprednisolone for 7 days (MS Remission) and 30 age- and sex-matched healthy individuals. TDH status was determined using an automated spectrophotometric analysis method. TDH levels in all patient groups and control subjects were compared with each other.

RESULTS

The lowest native thiol, total thiol levels and native thiol/total thiol ratio were found in the MS relapse patients in comparison to the MS control, MS remission groups and healthy controls. In contrast, disulphide levels, disulphide/native thiol and disulphide/total thiol ratios were highest in the MS relapse group compared to the other patient groups and healthy subjects.

CONCLUSION

Our findings indicate that increased oxidative stress in RRMS patients is reflected with decreased native and total thiol and increased disulphide levels. Since the formation of disulphide bonds is reversible, the progression of RRMS involving abnormal TDH may be controlled, converting disulphides to thiols. So, we suggest determining the dynamic TDH status as a novel and special biomarker in the diagnosis and prognosis of the RRMS patients.

Plasma thiol/disulphide homeostasis changes in patients with restless legs syndrome

OBJECTIVES

Restless legs syndrome (RLS) is a common neurological condition. Oxidative stress plays an important role in its pathogenesis. Thiol-disulphide homeostasis (TDH) is a new biomarker of oxidative stress. We studied plasma TDH to determine whether TDH could be used as a new biomarker for RLS and evaluated correlations between TDH and various disease severity rating scales.

METHODS

A total of 25 RLS patients and 25 healthy controls were included into the study. TDH status was determined using an automated spectrophotometric analysis method and correlations were analyzed between the TDH status and various disease rating scales in the RLS patients.

RESULTS

Plasma total (401±27 μmol/L) and native thiol (354±30 μmol/L) levels were significantly lower, but disulphide level (24±6 μmol/L) was significantly (<0.0001) higher in the RLS patients compared to the controls (455±36, 424±37, 15±5 μmol/L, respectively). The disulphide/native thiol and disulphide/total thiol ratios increased, in contrast, native thiol/total thiol ratio decreased significantly in the RLS patients compared to the healthy controls (<0.0001). The disulphide levels correlated positively with age and various rating scores of the RLS patients. International Restless Legs Syndrome Study Group (IRLSSG) rating score and age correlated negatively with the total and native thiol levels.

CONCLUSIONS

Our findings indicate increased oxidative stress in the RLS patients reflected by decreased native and total thiol, and increased disulphide levels and positive correlations between the disulphide levels and various rating scores. We suggest dynamic TDH status to be used as a novel biomarker for the diagnosis and follow-up of the RLS patients.

Can we Overcome the Predestined Poor Survival of Diabetic Patients? Perspectives from Pre- and Post-Dialysis

Although the survival of diabetic peritoneal dialysis (PD) patients has improved, it is still much worse than the survival of nondiabetic patients. Diabetes has its own risks for cardiovascular disease (CVD), such as increased levels of advanced glycation end-products, carbonyl and oxidative stress, and low-grade inflammation. An independent, graded association has been observed between a reduced glomerular filtration rate and the risk of CVD events in chronic kidney disease (CKD). Both CKD and diabetes synergistically lead to a high risk of CVD. It seems that the poor survival of diabetic PD patients is predestined at the initiation of dialysis because of multiple pre-existing risk factors and comorbid diseases, particularly CVD.

Recently, several trials were successful in improving the survival of patients with diabetic CKD. Tight control of glucose, blood pressure management using angiotensin converting-enzyme inhibitors or angiotensin II receptor blockers, and use of statins, antioxidants, or peroxisome proliferator-activated receptor gamma agonists may improve the survival of diabetic PD patients. However, simple correction of a single CVD risk factor is not likely to be effective. New PD solutions such as those low in glucose degradation products or those with icodextrin may also be effective in reducing the risk of CVD in diabetic PD patients. Therefore, multifactorial interventions—including diet control, early referral, and choice of an optimal PD solution—may improve the survival of diabetic PD patients.

Oxidative Stress Biomarkers and Left Ventricular Hypertrophy in Children with Chronic Kidney Disease

Cardiovascular diseases remain the most frequent cause of morbidity and mortality in patients with chronic kidney disease (CKD). The aim of the study was to assess the association between oxidative stress biomarkers and cardiovascular risk factors and left ventricular hypertrophy in children with CKD. Material and Methods. The studied group consisted of 65 patients aged 1.4-18.6 (mean 11.2) years with stages 1 to 5 CKD. Serum oxidized low-density lipoprotein (oxLDL), protein carbonyl group, creatinine, cystatin C, albumin, lipids, high-sensitivity C-reactive protein, intercellular adhesion molecule-1, insulin, plasma renin activity, and aldosterone levels were measured. Patients were divided into groups depending on CKD stage. Anthropometric measurements, ambulatory blood pressure (BP) measurements, and echocardiography with left ventricular mass (LVM) calculation were performed. Results. Serum oxLDL strongly correlated with creatinine (R = 0.246; p = 0.048), cystatin C (R = 0.346; p = 0.006), total cholesterol (R = 0.500; p < 0.001), triglycerides (R = 0.524; p < 0.001), low-density lipoprotein concentrations (R = 0.456; p < 0.001), and 24 hour BP values of systolic (R = 0.492; p = 0.002), diastolic (R = 0.515; p < 0.001), and mean arterial pressure (R = 0.537; p < 0.001). A significant correlation between oxLDL levels and LVM z-scores (R = 0.299; p = 0.016) was found. Conclusions. Hypertension and dyslipidemia correlated with lipid oxidation in children with CKD. oxLDLs seem to be valuable markers of oxidative stress in CKD patients, correlating with left ventricular hypertrophy.

Chard (Beta vulgaris var. cicla) extract improved hyperglycemia-induced oxidative stress and surfactant-associated protein alterations in rat lungs

CONTEXT

Chard is used as an antidiabetic agent by the diabetic patients in Turkey.

OBJECTIVE

The effect of chard extract [Beta vulgaris L. var. cicla (Chenopodiaceae)] on the antioxidant system and the expression of surfactant-associated proteins (SP) in the lungs of hyperglycemic rats were examined.

MATERIALS AND METHODS

Hyperglycemia was induced by a single dose of streptozotocin (60 mg/kg) provided intraperitoneally. Fourteen days after the rats were rendered hyperglycemic, the chard (2 g/kg/d), insulin (6 U/kg/d), and chard plus insulin (as mentioned above) were administered to rats for 45 d. On day 60, rats' lungs were removed. Oxidative stress parameters and SP expression were assayed.

RESULTS

The lungs of hyperglycemic rats were characterized by the induced lipid and protein oxidation, elevated myeloperoxidase and xanthine oxidase activities, decreased glutathione levels, and reduced tissue factor and antioxidant enzymes activities (catalase, superoxide dismutase, glutathione peroxidase, and glutathione-S-transferase). Chard treatment alone and chard treatment combined with insulin were capable of achieving a regression of pulmonary oxidative stress, by inhibiting lipid and protein oxidation, and restoring the antioxidant system of hyperglycemic rats. SP-A expressions were significantly unchanged in all groups, whereas pro-SP-C and SP-D expressions were reduced in hyperglycemic rats. Pro-SP-C and SP-D levels were increased by chard and insulin administrations alone and combined in hyperglycemic rats.

DISCUSSION AND CONCLUSION

All treatments have a positive effect on the surfactant and antioxidant systems of the lungs of hyperglycemic rats. The best therapeutic effect was provided by treatment with chard extract alone in the compensation of hyperglycemic symptoms.

Advanced oxidation protein products and ischaemia-modified albumin in obstructive sleep apnea

BACKGROUND

Several studies have shown that obstructive sleep apnea increases incidence of cardiovascular morbidity and mortality. The high systemic oxidative stress in obstructive sleep apnea has been considered as a major pathogenic mechanism leading to cardiovascular disease. Oxidative stress-related lipid and DNA oxidation in obstructive sleep apnea have been reported in the previous studies. In contrast, there is limited and contradictory information regarding protein oxidation in obstructive sleep apnea patients such as ischaemia-modified albumin and advanced oxidation protein products. Therefore, we aimed to investigate plasma ischaemia-modified albumin and advanced oxidation protein products and their correlation with total oxidative status and total antioxidative capacity in the obstructive sleep apnea patients.

METHODS

Plasma ischaemia-modified albumin, advanced oxidation protein products, total oxidative status and total antioxidative capacity were measured in 25 healthy volunteers and 59 obstructive sleep apnea patients diagnosed with polysomnography.

RESULTS

Plasma total antioxidative capacity was significantly lower (P = 0·012) and total oxidative status was significantly higher (P < 0·001) in the patients compared to the controls demonstrating increased oxidative stress in the patients. Plasma advanced oxidation protein products were significantly higher in the patients than the controls (P = 0·024). Plasma ischaemia-modified albumin levels were not statistically different between the obstructive sleep apnea patients and controls (P = 0·74).

CONCLUSIONS

We conclude that high systemic oxidative stress in obstructive sleep apnea is reflected by increased advanced oxidation protein products without causing an increase in ischaemia-modified albumin.

Chromium, selenium, and zinc multimineral enriched yeast supplementation ameliorates diabetes symptom in streptozocin-induced mice

Chromium, selenium, and zinc malnutrition has been implicated in the pathogenesis of diabetic mellitus. This study aims to investigate the effects of novel multiminerals-enriched yeast (MMEY) which are minerals supplementation containing elevated levels of chromium, selenium, and zinc simultaneously in a diabetic animal model. Streptozocin-induced diabetic male Balb/c mice (n = 80) were randomly divided into diabetes control group and three treatment groups. They were administrated oral gavages with low, medium, or high doses of MMEY, respectively. Meanwhile, healthy male Balb/c mice (n = 40) of the same body weight were randomly assigned into normal control group and high dose of MMEY control group. After 8 weeks duration of treatment, the animals were sacrificed by cervical dislocation. Serum glucose concentrations, lipid profiles, oxidative/antioxidant, and immunity status were determined. No significant adverse effects were observed in the high-dose MMEY control group. Treatment of the diabetic mice with medium- or high-dose MMEY significantly decreased serum glucose, triglyceride, total cholesterol, and malondialdehyde and increased high-density lipoprotein cholesterol, glutathione, and the activities of superoxide dismutase and glutathione peroxidase. In addition, MMEY ameliorated the pathological damage of the pancreatic islets, elevated the thymus or spleen coefficient, and increased the expressions of interleukin-2 and -4 in spleen lymphocytes compared with unsupplemented diabetic mice. In conclusion, these results indicate that supplemental MMEY inhibits hyperglycemia, abates oxidative stress, modulates disorders of lipid metabolism, and reduces the impairment of immune function in diabetic mice; especially notable are the protective effects of medium doses of MMEY on the islet cells of diabetic mice.

In vitro upregulation of erythrocytes glucose uptake by Rhaphnus sativa extract in diabetic patients

In diabetes, both the increase in the oxidative stress and the decrease in the antioxidant defense may elevate the susceptibility of diabetic patients to many pathological complications. So, the aim of the present study was to investigate the effect of superoxide dismutase (SOD) like activity protein, partially purified from radish (Rhaphnus sativa) on uptake of glucose in vitro by erythrocytes of diabetic patients. In hyperglycemic patients, erythrocytes malondialdehyde level was highly significantly increased (P < 0.0001) than that of the control. However, the erythrocytes glutathione content and glutathione reductase activity, were both highly significantly decreased (P < 0.0001) compared to that corresponding control values. The glucose uptake by erythrocytes of diabetic patients was highly significantly decreased (P < 0.0001) with increasing hyperglycemia, while it was highly significantly elevated (p < 0.0001) after addition of the partially purified SOD like activity protein. On the other hand, the malondialdehyde concentration was highly significantly reduced (p < 0.001) on adding the partially purified protein. It thus can be concluded that, an appropriate support for enhancing antioxidant supply, such as SOD like activity protein from natural sources, may help control blood glucose level and may prevent clinical complications of diabetes.

A fluorescent dual labeling technique for the quantitative measurement of reduced and oxidized protein thiols in tissue samples

Oxidative stress can result in the reversible oxidation of protein thiols. Because the activity of numerous proteins is sensitive to thiol oxidation, this has the potential to affect many cellular functions. We describe a highly sensitive, quantitative labeling technique that measures global and specific protein thiol oxidative state in skeletal muscle tissue. The technique involves labeling the reduced and oxidized protein thiols with different fluorescent dyes. The resulting sample is assayed using a 96-well plate fluorimeter, or individual protein bands are separated using SDS-PAGE. We show that artifactual oxidation during sample preparation and analysis has the potential to confound results, and techniques to prevent this are described. We tested the technique by analyzing the muscles of mdx and c57 mice and found that the muscles of mdx mice were significantly (p<0.05) more oxidized (13.1±1.5% oxidized thiols) than those of c57 mice (8.9±0.7% oxidized thiols). This technique provides an effective means to measure the extent to which oxidative stress affects the oxidation of protein thiols in biological tissues.

The oxidative stress status in diabetes mellitus and diabetic nephropathy

The aim of this study is to assess the oxidative stress status in diabetes mellitus (DM) and diabetic nephropathy. The study group comprised 40 control subjects, 40 type 2 DM patients without complications and 37 diabetic nephropathies. Compared with control subjects, superoxide dismutase, glutathione peroxidase, catalase, vitamin C were decreased (P < 0.01). There was a significant increase in serum malondialdehyde (MDA), conjugated diene (CD), advanced oxidation protein products (AOPP), protein carbonyl (PC) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in diabetes patients when compared with normal subjects (P < 0.01). Moreover, these indexes were much higher in diabetic nephropathy than that of diabetic patients without vascular complications (P < 0.05, P < 0.01). There was a significant correlation between the serum glucose levels and PC, 8-OHdG (P < 0.05, P < 0.01). There were highly significant positive correlation of CD and MDA, AOPP and PC (P < 0.01). Plasma AOPP levels had a significant correlation with PC levels (P < 0.01). Our findings suggested that diabetes patients have more severe oxidative stress than normal persons and higher oxidative stress in diabetic nephropathy than those in patients without complications. Oxidative stress may play an important intermediary role in the pathogenesis of diabetes complications.

Oxidative stress biomarkers and chromogranin A in uremic patients: effects of dialytic treatment

OBJECTIVE

To evaluate oxidative stress in uremia and dialysis and chromogranin A, a stress hormone that could be related to oxidative processes.

METHODS

Plasma oxidative stress biomarkers (-SH, 8-OHdG, and ox-LDL) and chromogranin A were measured in 89 outpatients (21 uremic patients, 17 in peritoneal dialysis, and 51 in haemodialysis), and in 18 subjects with normal renal function.

RESULTS

-SH groups were significantly reduced in heamodialysis, peritoneal, and uremic patients as compared with the control group (p=0.01), while 8-OHdG was increased (p<0.01). No differences were observed for ox-LDL. Chromogranin A was increased in uremic, peritoneal and haemodialysis patients (p<0.01), showing a positive correlation to 8-OHdG (p<0.01).

CONCLUSION

Oxidative stress biomarkers and chromogranin A levels differ between control subjects when compared to both uremic and dialysis patients. No differences were observed between uremic and dialysis patients, suggesting that uremia is the major source of the increase in oxidative stress and CgA levels in patients with end stage renal disease.

Oxidative stress parameters as possible urine markers in patients with diabetic nephropathy

OBJECTIVE

Reactive oxygen species play a crucial role in the pathogenesis of diabetic nephropathy (DN). The present study was performed to assess oxidative stress parameters-thiobarbituric acid reactive substances (TBARS), reactive carbonyl derivates (RCDs), and total sulfhydryl groups (TSHGs)-in serum and urine of patients with DN.

METHODS

All parameters were determined in patients with type 2 and type 1 diabetes mellitus and microalbuminuria (DMT2-MIA, DMT1-MIA, respectively) and patients with type 2 diabetes mellitus and macroalbuminuria (DMT2-MAA) compared to healthy controls.

RESULTS

Serum and urine TBARS levels were higher in all patients with DN and microalbiminuria compared to the control group. RCD levels significantly increased in serum of patients with DMT2 relative to the controls as well as in urine of patients with DMT2-MAA and DMT1-MIA. In all groups of patients, TSHGs decreased in serum but not in urine of patients with DMT2-MAA.

CONCLUSION

Urine TBARS, RCDs, and TSHGs could be proposed as possible markers for oxidative damage of kidney in DN.

Differentially displayed proteins as a tool for the development of type 2 diabetes

Background

Type 2 diabetes is a complex disease that still requires a great deal of work to be carried out to understand the pathophysiology. Recently, researchers have focused on studying the organs and tissues known to be involved in the development of the type 2 phenotype using a proteomic approach. Little work has been reported on plasma of type 2 diabetics in whom the clinical status has been well characterized. In this study, changes in plasma proteins of type 2 diabetics were investigated by proteomic analysis in well-characterized individuals with type 2 diabetes (early and late stage) and control groups (with or without a family history of diabetes).

Methods

Samples were analysed by two-dimensional gel electrophoresis and significantly differentiated proteins were identified by nano-LC-ESI-MS.

Results

A total of 12 protein signatures that were differentially displayed with high significance compared with controls were selected. Four of the differentially displayed proteins were identified as haptoglobin alpha2, haptoglobin Hp2(fragment) and transthyretin and Chain A (formerly prealbumin), and all were up-regulated. Thiol-specific antioxidant protein, Chain A, tertiary structures of three amyloidogenic transthretin variants and haptoglobin-related protein precursor were all down-regulated in controls with a family history of diabetes, early and late diabetic patients in comparison with the control.

Conclusion

A proteomic-based approach was used to discover and identify the differentially expressed proteins in various states of type 2 diabetes.

Protein carbonylation in kidney medulla of the spontaneously hypertensive rat

Enhanced generation of ROS has been reported in models of hypertension such as the spontaneously hypertensive rat (SHR). Impairment of kidney function has been implicated in development and progression of hypertension, and the renal medulla appears to play an important role in regulating long-term blood pressure. A key biomarker of oxidative stress is the formation of protein carbonyls, which we set out to characterize in the SHR medulla. We identified 11 proteins that were differentially carbonylated in SHR medulla in comparison to normotensive wistars including enolase 1, catalase, carbonic anhydrase II, transferrin and members of the aldo-keto-reductase family. This enhanced protein oxidation was not only accompanied by an increase in intracellular iron deposition, but aldo-keto-reductase activity was also significantly less in SHR medulla than in normotensive Wistars. Oxidative stress appears selectively to target a subset of proteins in SHR kidney and modification of these proteins may in turn contribute to the renopathy associated with hypertension.

Determination of thiols and disulfides via HPLC quantification of 5-thio-2-nitrobenzoic acid

This work presents an assay for total thiols and total disulfides in biological samples via HPLC quantification of 5-thio-2-nitrobenzoic acid (TNB) derived from the reaction of thiols with 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB, Ellman's reagent). This method also provides simultaneous quantification of glutathione (GSH) via the measurement of the GSH-DTNB adduct (GSH-TNB). By using 326nm as the detecting wavelength, the HPLC detection limit for TNB and the GSH-TNB adduct was determined to be 15 and 7.5pmol respectively. A recovery study with OVCAR-3 cells revealed that the recovery yields for TNB in the procedures for determining non-protein thiols, protein thiols, non-protein disulfides, and protein disulfides were 99.4+/-1.2% (n=3), 98.1+/-5.0% (n=3), 95.6+/-0.9% (n=3), and 96.6+/-2.3% (n=3) respectively. The recovery yield for GSH-TNB in the procedures for determining non-protein thiols, protein thiols, non-protein disulfides, and protein disulfides was 99.0+/-0.3% (n=3), 95.1+/-4.9% (n=3), 96.8+/-0.6% (n=3), and 95.1+/-2.9% (n=3) respectively. The reproducibility, expressed as the relative standard deviation for the analyte, for TNB was determined to be 2.8% (n=6) for non-protein thiols, 3.9% (n=6) for protein thiols, 3.6% (n=6) for non-protein disulfides and 4.6% (n=6) for protein disulfides. The reproducibility for GSH-TNB was determined to be 1.6% (n=6) for non-protein thiols and 2.6% (n=6) for non-protein disulfides. By comparing the amount of GSH determined in a biological sample before NaBH(4) reduction with that after the reduction, this method can provide information associated with thiol glutathionylation which would be useful for protein glutathionylation study. This method should be applicable to cellular, subcellular, protein, or other biomatrix samples for thiol and disulfide quantification and will be a useful analytical method in the study of thiol redox state and thiol glutathionylation.

Characterization of a novel dithiocarbamate glutathione reductase inhibitor and its use as a tool to modulate intracellular glutathione

Thiol redox state (TRS) is an important parameter to reflect intracellular oxidative stress and is associated with various normal and abnormal biochemical processes. Agents that can be used to increase intracellular TRS will be valuable tools in TRS-related research. Glutathione reductase (GR) is a critical enzyme in the homeostasis of TRS. The enzyme catalyzes the reduction of GSSG to GSH to maintain a high GSH:GSSG ratio. Inhibition of the enzyme can be used to increase TRS. Despite the reports of various GR inhibitors, N,N-bis(2-chloroethyl)-N-nitrosourea, an anticancer drug with IC(50) = 647 microm against yeast GR, remains the most commonly used GR inhibitor in the literature. However, the toxicity caused by nonspecific interactions, as well as inhibition of DNA synthesis, complicates the use of N,N-bis(2-chloroethyl)-N-nitrosourea as a GR inhibitor. We report 2-acetylamino-3-[4-(2-acetylamino-2-carboxyethylsulfanylthiocarbonylamino)phenylthiocarbamoylsulfanyl]propionic acid (2-AAPA) as a novel irreversible GR inhibitor. 2-AAPA was prepared by one-step synthesis from commercially available reagents. The K(i) and k(inact) of 2-AAPA against yeast GR were determined to be 56 microm and 0.1 min(-1), respectively. At the concentration that produced >80% yeast GR inhibition, 2-AAPA showed no inhibition against glutamylcysteine synthetase, glutathione synthetase, catalase, and superoxide dismutase, but minimal inhibition against glutathione S-transferase and glutathione peroxidase. In CV-1 cells, 2-AAPA (0.1 mm) produced 97% GR inhibition, 25% GSH reduction, and a 5-fold increase in GSSG in 20 min. The compound can be a useful tool in TRS-related research.

Evidence for oxidative stress at elevated plasma thiol levels in chronic exposure to carbon disulfide (CS2) and coronary heart disease

OBJECTIVES

Oxidative stress in plasma may be promoted by plasma thiols such as homocysteine. However, other thiols such as glutathione may also exert antioxidant effects in vitro and in vivo. To further investigate whether plasma thiols act as prooxidants or antioxidants, we compared plasma oxidative status in patients with coronary heart disease (CHD) and in subjects occupationally exposed to carbon disulfide (CS(2)).

METHODS

Fifty-five subjects chronically exposed to CS(2), 53 CHD patients, and 52 healthy controls were examined. To assess plasma oxidative status, concentrations of thiobarbituric reactive substances (TBARS) and total antioxidative capacity (TAC), as well as ferritin and ceruloplasmin were determined. Antioxidative reserve was assessed by the determination of vitamine E, uric acid, superoxide dismutase, catalase, and glutathion peroxidase. In addition, protein and non-protein plasma thiol levels were measured.

RESULTS

Patients in both groups had increased levels of plasma thiols as compared to controls: CS(2)-exposed subjects presented with increased levels of thiols associated with plasma proteins, whereas CHD patients presented with elevated total homocysteine and cysteine levels. TBARS were significantly increased and TAC was significantly decreased both in CS(2)-exposed subjects and in CHD patients. In addition decreased activity of glutathione peroxidase, an antioxidative enzyme inhibited by thiol-containing compounds, was noted in both groups.

CONCLUSION

These results demonstrate that regardless of their metabolic origin increased thiols are associated with increased oxidative stress in plasma.

Dialyzer membrane characteristics and outcome of patients with type 2 diabetes on maintenance hemodialysis

BACKGROUND

Effects of dialyzer membrane characteristics on morbidity and mortality are highly controversial.

METHODS

Post hoc, we analyzed data from the German Diabetes and Dialysis Study that evaluated atorvastatin in high-risk patients. Four groups were identified being constantly dialyzed with high-flux synthetic (n = 241), low-flux synthetic (n = 247), low-flux semisynthetic (n = 119), or cellulosic low-flux membranes (n = 41). Two end points were investigated: (1) a cardiovascular end point consisting of cardiac death, nonfatal myocardial infarction, and stroke and (2) death.

RESULTS

After 4 years of follow-up, adjusted multivariate relative risks (RRs) were calculated. The RR to reach a cardiovascular end point was greater for patients dialyzed with cellulosic low-flux (RR, 2.33; 95% confidence interval [CI], 1.38 to 3.94; P = 0.002), low-flux semisynthetic (RR, 1.92; 95% CI, 1.35 to 2.73; P = 0.0003), or low-flux synthetic membranes (RR, 1.35; 95% CI, 0.99 to 1.85; P = 0.06) than for those treated with high-flux synthetic dialyzers. The likelihood to die was greater with cellulosic low-flux (RR, 4.14; 95% CI, 2.79 to 6.15; P < 0.0001), low-flux semisynthetic (RR, 2.24; 95% CI, 1.66 to 3.02; P < 0.0001), and low-flux synthetic membranes (RR, 1.59; 95% CI, 1.22 to 2.07; P = 0.0006) than with high-flux synthetic membranes. With respect to low-flux synthetic membranes, RRs of mortality for patients using cellulosic low-flux and low-flux semisynthetic membranes were 161% (RR, 2.61; 95 % CI, 1.80 to 3.79; P < 0.0001) and 41% (RR, 1.41; 95% CI, 1.07 to 1.86; P = 0.016) greater. Cellulosic low-flux membrane use was associated with an 85% (RR, 1.85; 95% CI, 1.24 to 2.76; P = 0.0025) greater RR of death than low-flux semisynthetic membranes.

CONCLUSION

These data suggest that biocompatibility and permeability may impact on death and cardiovascular events in hemodialysis patients with type 2 diabetes mellitus.