Diagnostic potential of YKL-40 in bladder cancer.

OBJECTIVES: YKL-40 is a glycoprotein, which is thought to play a role in inflammatory conditions and tissue remodeling. Although it has been investigated in numerous cancers, there is very limited knowledge about the role of YKL-40 in bladder cancer. In this study, our aim was to determine the levels of YKL-40 in the sera and urines of the patients with bladder cancer, and compare it to urinary bladder tumor antigen (BTA), a tumor marker that can be used in the diagnosis of bladder cancer. METHODS: The study was comprised of 2 major groups as 65 healthy controls and 67 patients with bladder cancer. The patient group was also divided into subgroups according to tumor stage and grade. Serum and urine YKL-40 levels and urine BTA levels in controls and patients were determined using commercially available enzyme-linked immunosorbent assay kits. RESULTS: Serum YKL-40 and urinary BTA levels were significantly elevated in patients and all patient subgroups compared to healthy controls. Urine YKL-40 levels, on the other hand, were significantly elevated in all subgroups except low stage (Ta) and low grade, compared to controls. Although serum YKL-40 levels could not differentiate any subgroup from one another, urinary BTA could only differentiate low stage (Ta) from all invasive (T1-T4) cancers. However, urine YKL-40 levels were significantly elevated in all invasive subgroups (T1, T2-T4, and T1-T4), compared to low stage (Ta). CONCLUSIONS: In summary, urine YKL-40 levels can be used to assist BTA in the diagnosis of bladder cancer as a marker for early invasiveness and thus help determine its treatment regimen.

Serum levels of epidermal growth factor, transforming growth factor, and c-erbB2 in ovarian cancer.

OBJECTIVE: This study aimed to investigate serum levels of epidermal growth factor (EGF), transforming growth factor α (TGF-α), and c-erbB2 in patients with ovarian cancer. MATERIALS AND METHODS: In this retrospective cohort study, the study and control groups were composed of 43 women with a prediagnosis of ovarian cancer and 43 healthy women, respectively. Blood samples from all women were obtained and studied by enzyme-linked immunosorbent assay kits for EGF, TGF-α, and c-erbB2. After surgery of the study group, ovarian cancer was confirmed and compared with control group. Stage, grade, and histological types were defined after histopathologic examination, and subgroups were constructed and compared. RESULTS: Serum EGF, TGF-α, and c-erbB2 levels were significantly increased in study group compared with those in the control group (P < 0.001). There were no differences in serum levels of EGF, TGF-α, and c-erbB2 among all stages, grades, and histological types of ovarian cancer. If 47.90 pg/mL was selected as the cutoff value, EGF has an 80% sensitivity and a 65% specificity for detecting ovarian cancer. The cutoff value of 41,095.00 pg/mL for TGF-α has a 90% sensitivity and a 72% specificity for detecting ovarian cancer. The c-erbB2 level of 4.63 pg/mL as the cutoff value has an 83% sensitivity and a 76% specificity for predicting ovarian cancer. CONCLUSIONS: Serum levels of EGF, TGF-α, and c-erbB2 may be used for diagnosing ovarian cancer.

Leukocyte DNA damage in children with iron deficiency anemia: effect of iron supplementation.

Iron deficiency is frequently associated with anemia. Iron is a transition-metal ion, and it can induce free radical formation, which leads to formation of various lesions in DNA, proteins, and lipids. The aim of this study was to investigate baseline oxidative DNA damage and to clarify the role of the administration of a therapeutic dose of iron on DNA oxidation in children with iron deficiency anemia (IDA). Twenty-seven children with IDA and 20 healthy children were enrolled in the study. Leukocyte DNA damage (strand breaks and Fpg-sensitive sites) was assessed using comet assay before and after 12 weeks of daily iron administration. Before the iron administration, the frequency of DNA strand breaks in the children with IDA was found to be lower than those in the control group (P < 0.05), but there was not a significant difference for frequency of Fpg-sensitive sites. After 12 weeks of iron administration, the frequency of both DNA strand breaks and Fpg-sensitive sites were found to be increased (P < 0.01). No significant association was determined between DNA damage parameters and hemoglobin, hematocrit, serum iron, total iron binding capacity, and ferritin. In conclusion, basal level of DNA strand breaks is at a low level in children with IDA. After iron administration, DNA strand breaks and Fpg-sensitive sites, which represent oxidatively damaged DNA, increased. However, this increase was unrelated to serum level of iron and ferritin.

Assessment of DNA nucleo base oxidation and antioxidant defense in postmenopausal women under hormone replacement therapy.

BACKGROUND AND OBJECTIVE: The aim of the present study was to evaluate oxidative stress by investing oxidatively damaged DNA AS Formamidopyrimidine DNA glycosylase (Fpg) -sensitive sites, glutathione peroxidase (GPx), superoxide dismutase (SOD) activities reduced glutathione (GSH) level and nitrite level as satble end product of in women receiving hormone replacement therapy (HRT). MATERIALS AND METHODS: 127 healthy postmenopausal women receiving HRT and 25 healthy control postmenopausal women were included in this study. Women receiving HRT, comprised surgical menopausal women who underwent surgery for benign conditions and received conjugated equine estrogen, 0.625 mg/day for 1 year (group 1), 5 years (group 2) and more than 10 years (group 3), spontaneous postmenopausal women received conjugated equine estrogen, 0.625 (Premarin) mg/day and medroxyprogesterone acetate, 2.5 mg/day (Premelle) for 1 year (group 4), 5 years (group 5) and more than 5 years (group 6).We investigated in the present study the effects of HRT on nitrite level and GSH level, activities of SOD and GPx and oxidative damage to DNA by comet assays by measuring levels of Fpg-sensitive sites. RESULTS: Although no significant differences were found in the SOD activities, in total group receiving HRT, increased DNA oxidation (P<0.001) together with an increased GPx activity (P<0.001) and nitrite level (P<0.001) as well as a decreased GSH level (P < 0.05) as compared with controls were observed. CONCLUSION: Estrogen alone or oestrogen in combination with progesterone and duration of use did not significantly alter the results. We evaluated that caused oxidative stress by investigating oxidative DNA damage as Fp-sensitive sites and GSH.NO levels in women receiving HRT.

DNA damage and glutathione level in children with asthma bronchiale: effect of antiasthmatic therapy.

When the production of reactive oxygen species (ROS) exceeds the capacity of antioxidant defences, a condition known as oxidative stress occurs and it has been implicated in many pathological conditions including asthma. Interaction of ROS with DNA may result in mutagenic oxidative base modifications such as 8-hydroxydeoxyguanosine (8-oxo-dGuo) and DNA strand breaks. Reduced glutathione (GSH) serves as a powerful antioxidant against harmful effects of ROS. The aim of this study was to describe DNA damage as level of DNA strand breaks and formamidopyrimidine DNA glycosylase (Fpg)-sensitive sites, which reflects oxidative DNA damage and GSH level in children with mild-to-moderate persistent asthma; and to examine the effect of antiasthmatic therapy on these DNA damage parameters and GSH level. Before and after 8 wk of antiasthmatic therapy blood samples were taken, DNA strand breaks and Fpg-sensitive sites in peripheral leukocytes were determined by comet assay, GSH level of whole blood was measured by spectrophotometric method. DNA strand breaks and Fpg-sensitive sites in the asthma group were found to be increased as compared with control group. GSH level in the asthma group was not significantly different from those in the control group. Levels of strand breaks, Fpg-sensitive sites and GSH were found to be decreased in the asthma group after the treatment. In conclusion, oxidative DNA damage (strand breaks and Fpg-sensitive sites) is at a high level in children with asthma. DNA damage parameters and GSH level were found to be decreased after therapy. Our findings imply that antiasthmatic therapy including glucocorticosteroids not only controls asthma but also decreases mutation risk in children with asthma bronchiale.

Circulating p53 and cytochrome c levels in acute myocardial infarction patients.

BACKGROUND: Apoptosis causes myocardiocyte loss during and after myocardial infarction. Therapeutic approaches designed to arrest apoptosis would be a significant new development in the recovery of acute myocardial infarction (AMI). In order to examine apoptotic markers in the circulation, serum levels of p53 and cytochrome c were assessed in patients with AMI. METHODS: Blood samples were taken on admission (before initiation of therapy) and on the 3rd and 7th days of hospitalization. Serum levels of p53 and cytochrome c were measured by enzyme-linked immunassay. RESULTS: The serum level of p53 was higher in AMI patients on admission compared to the control group. A time-dependent decrease was observed in the serum level of p53, but there was no significant change in the serum level of cytochrome c during therapy. CONCLUSIONS: p53, but not cytochrome c, appears to have potential as a biomarker for reporting on apoptosis following myocardial infarction.

Serum levels of p53 and cytochrome c in subjects with type 2 diabetes and impaired glucose tolerance.

PURPOSE: To examine apoptotic markers in serum of subjects with diabetes and impaired glucose tolerance (IGT). Serum levels of p53 and cytochrome c, regulator molecules for apoptosis, were measured in subjects with type 2 diabetes, subjects with IGT and healthy controls. METHODS: Forty one subjects with type 2 diabetes, 27 with IGT and 27 healthy volunteers were included in the study. Serum level of cytochrome c and p53 were measured with competitive ELISA. RESULTS: Serum levels of p53 were lower in the group of subjects with type 2 diabetes (085+/-0.39 U/ml) than in controls (1.09+/-0.49 U/ml) (P < 0.05) and in the subjects with IGT (0.98+/-0.37 U/ml) (P < 0.05). There was no significant difference between the group with IGT and controls. Also, there was no difference for serum level of cytochrome c among the groups. In the group of subjects with type 2 diabetes, serum level of cytochrome c was mildly correlated with HbA1c (r:0.39, P < 0.05). CONCLUSION: The present study shows that the serum level of p53 is lower in the patients with type 2 diabetes than in controls or in subjects with IGT. No difference was seen among the the groups for the serum level of cytochrome c.

DNA oxidation and antioxidant status in breast cancer.

PURPOSE: : Oxidant/antioxidant balance has been suggested as an important factor for initiation and progression of cancer. The objective of this study was to determine 8-hydroxydeoxyguanosine (8-OHdG) level as a marker of oxidative DNA damage, glutathione peroxidase (G-Px), and superoxide dismutase (SOD) activities as antioxidant activity, in sera from women with breast cancer. METHODS: : Forty-nine patients with malign breast tumor were included in the study. Blood samples were collected before the surgical operation. Serum level of 8-OHdG was measured with a competitive enzyme-linked immunusorbent assay kit, SOD, and G-Px activities were measured by spectrophotometric kits. RESULTS: : 8-Hydroxydeoxyguanosine level and SOD activity were found to be increased in breast cancer group as compared with control group. Glutathione peroxidase activity in the breast cancer group was lower than those in the control group. The ratio of 8-OHdG/G-Px in breast cancer patients was found to be higher than those in the controls. There were correlations between 8-OHdG and CA19-9 (r = 0.77; P < 0.01); age and G-Px (r = -0.84; P < 0.05) in the breast cancer group. CONCLUSIONS: : Data show that serum levels of 8-OHdG and SOD activities are higher in patients with breast cancer. Glutathione peroxidase activity is lower in the breast cancer group. Increased ratio of 8-OHdG/G-Px in breast cancer patients is the evidence for impaired oxidant/ antioxidant balance in breast cancer.

Oxidative DNA damage and antioxidant defense after reperfusion in acute myocardial infarction.

PURPOSE: Myocardial damage mediated by oxidative stress during acute myocardial infarction (MI) has been suggested as an obstructive factor on recovery after an MI. 8-Hydroxydeoxyguanosine (8-OHdG) is a marker for oxidative DNA damage; superoxide dismutase (SOD) and glutathione peroxidase (G-Px) are major antioxidant enzymes. We determined changes in the plasma level of 8-OHdG and activities of SOD and G-Px in patients with MI and examined the relations between those changes and other cardiac markers. METHODS: Blood samples were taken at the beginning of the therapy, on the third day of hospitalization, and on the day patients were discharged home. Plasma level of 8-OHdG and SOD and G-Px activities were measured by enzyme-linked immunosorbent assay and spectrophotometric kits, respectively. RESULTS: 8-Hydroxydeoxyguanosine level at the beginning of the therapy was found to be decreased on the third day of therapy and on the day patients were discharged home. With respect to the treatment way, 8-OHdG level was found to be slightly decreased on the third day of therapy and then remained stable in the group treated with thrombolytic agents. However, 8-OHdG level was found to be sharply decreased on the third day of therapy in the group that underwent primary percutaneous transluminal coronary angioplasty. No significant relations were determined between those measured parameters and serum levels of cardiac markers. CONCLUSION: Although not correlated with other cardiac markers, plasma level of 8-OHdG shows a decrease after reperfusion therapy in patients with MI, and primary percutaneous transluminal coronary angioplasty seems much more effective than thrombolytic therapy for providing a low level of 8-OHdG.

Assessment of DNA oxidation and antioxidant activity in hypertensive patients with chronic kidney disease.

The aim of this study was to evaluate the oxidative DNA damage, antioxidant activity, and effects of antihypertensive drugs on oxidative stress in hypertensive patients with different stages of chronic kidney disease (CKD). Fifty-three non-dialyzed hypertensive CKD patients were included by the study. Serum and urinary 8-hydroxydeoxy guanosine (8-OHdG) levels (as a marker of oxidative DNA damage), serum superoxide dismutase (SOD), and glutathione peroxidase (G-Px) activities (as antioxidant enzymes) were measured. SOD activity was higher and G-Px activity was lower in the patient group as compared to control group. Serum and urinary 8-OHdG levels were found to be higher in the patients with proteinuria greater than 3 g/day than those in the patients with proteinuria less than 3 g/day. It has been determined that G-Px activity and urinary 8-OHdG level were lower in the patients treated with angiotensin-converting enzyme (ACE) inhibitor compared to patients treated with calcium channel blocker. The present data show oxidative DNA damage at a higher level in the patients with proteinuria greater than 3 g/day. In comparison to a calcium channel blocker, an ACE inhibitor seems much more protective against oxidative DNA damage in hypertensive patients with different stages of CKD.

Oxidative DNA damage and antioxidant activity in patients with inflammatory bowel disease.

Chronic inflammation may contribute to cancer risk through the accumulation of specific products as a result of DNA damage. Endogenous antioxidant enzymes prevent the formation of these harmful products. Oxidative DNA damage and endogenous antioxidant defense were determined in patients with inflammatory bowel disease (IBD). Plasma levels of 8-hydroxydeoxyguanosine (8-OHdG) and nitric oxide (NO) and plasma activities of glutathione peroxidase (G-Px) and superoxide dismutase (SOD) were determined in patients with IBD by ELISA and spectrophotometric assay, respectively. Plasma levels of 8-OHdG, SOD, and G-Px activity were found to be increased in the patient group compared to the control group (P < 0.02, P < 0.001, and P < 0.001, respectively), whereas NO was unchanged. 8-OHdG level was found to be weakly correlated with age, NO, and SOD. The results show increased DNA damage in patients with IBD. This may explain the increased risk of developing colon cancer in these patients.

Nitric oxide and antioxidant defense in patients with gastric cancer.

In the present study, total nitrate and nitrite level (as end product of nitric oxide), superoxide dismutase activity, and glutathione peroxidase activity in leukocytes were determined in patients with gastric cancer, and the relationship between measured parameters and tumor grade were evaluated. Leukocyte nitrate and nitrite level was found to be increased and superoxide dismutase activity was found to be decreased in patients compared to controls. When the patient group was categorized, nitrate and nitrite level was found to be higher in patients with a high-grade tumor than in patients with a grade I tumor. We concluded that an increased level of leukocyte nitrate and nitrite is related to tumor grade in patients with gastric cancer; antioxidant activity is also impaired in these patients but it does not seem to be related to grade of tumor.

Methylguanine DNA methyl transferase activities, glutathione s transferase and nitric oxide in bladder cancer patients.

Tumor formation is a multistep process that can be divided in to the stages of tumor initiation, promotion, and progression. DNA repair protein; MGMT is a key suicide enzyme that repairs the mispairing base methylguanine, which is induced in DNA as a minor lesion. The glutathione S transferases (GSTs) are a family of enzymes that are important to protect against alkylating agents. Nitric oxide, contributes to the regulation of tumor angiogenesis. A substantial body of experimental evidence supports the hypothesis that tumor angiogenesis is fundamental for the growth and metastasis of solid tumors. We measured the activities of GST, MGMT, and levels of NO3-/NO2- in the leukocytes from patients with bladder carcinoma and healthy controls and activities of MGMT in the tissue from patients with bladder carcinoma and adjacent normal tissue in bladder. Both GST and tissue MGMT activites were significantly increased in the patient group. There was no significant difference between controls and patients for MGMT activity in peripheral blood leukocytes (PBL). Nitrate/nitrite levels in PBL, there was no significant difference between controls and patients. Nitrate/nitrite levels were increased in G2-G3 tumors. In conclusion, we determined high concentrations of nitrite in leukocytes are suspected alkylation damage by induction nitrosamine. Increased DNA alkylation damage may lead the stimulation of MGMT and GST.

Effect of alpha-lipoic acid supplementation on markers of protein oxidation in post-mitotic tissues of ageing rat.

In the present study, we investigated whether DL-alpha-lipoic acid (LA) supplementation could have prooxidant or antioxidant effects on oxidative protein damage parameters such as protein carbonyl (PCO), nitrotyrosine (NT), advanced oxidation protein products (AOPP), and protein thiol (P-SH), as well as oxidative stress parameters such as total thiol (T-SH), non-protein thiol (Np-SH), and lipid hydroperoxide (LHP) in the brain and the skeletal muscle tissue of aged rats. PCO, and NT levels were increased, AOPP and P-SH levels were not changed in the brain tissue of aged rats given LA supplementation. On the other hand, TSH, Np-SH, and LHP levels were decreased in the brain tissue of aged rats given LA supplementation. The levels of the same parameters were not significantly different in the skeletal muscle tissue of aged rats given LA supplementation. The increased levels of protein oxidation markers such as PCO, and NT in the brain tissue of LA-supplemented aged rats compared with non-supplemented aged rats may suggest that oxidative protein damage is increased in LA-supplemented aged rats. We assume that an explanation for our findings regarding LA supplementation on protein oxidation markers in the brain tissue of aged rats may be due to the prooxidant effects of LA. Depending on post-mitotic tissue type and dosage of LA, the prooxidant effects of LA supplementation, should be considered in future studies.

Significance of the O6-methylguanine-DNA methyltransferase and glutathione S-transferase activity in the sera of patients with malignant and benign ovarian tumors.

OBJECTIVE: To demonstrate O6-methylguanine-DNA methyltransferase (MGMT) and glutathione S-transferase (GST) activities by analyzing the sera separately obtained from patients with malignant ovarian tumors, benign ovarian tumors, and healthy individuals. STUDY DESIGN: Fourty-nine patients with ovarian cancer, nine patients with benign tumors, and 22 healthy women were included in this study. Blood samples were obtained from all the subjects in the malignant-tumor, benign-tumor, and control groups. Patients with malignant tumors underwent second and third phlebotomies one week following the surgery and after the chemotherapy regimen, respectively. MGMT, GST, and protein levels were measured for each serum sample. GST activity of the samples was measured by the method of Habig et al. using l-chloro-2-4 dinitrobenzene (CDNB) as substrate. MGMT activity was measured by the transfer of radio labelled methyl groups from a prepared MG-DNA substrate to the enzyme fraction of serum. Protein concentration was measured by biuret method. RESULTS: Our work demonstrated that untreated patients with malignant ovarian tumors revealed significantly greater MGMT and GST activities in their sera than did both healthy individuals and patients with benign ovarian tumors, while no significant difference was found between the healthy group and the patients with benign ovarian tumors with respect to their sera MGMT and GST activities. GST activity following chemotherapy was significantly lower than the postoperative values preceding chemotherapy. A relationship between sera MGMT and GST activities, tumor histology and pathology was not found in this study. CONCLUSION: Our work suggests the fact that detection of sera MGMT and GST activities is important in diagnostic and therapeutic approaches during the course of ovarian cancer.

The effect of prostate cancer and antiandrogenic therapy on lipid peroxidation and antioxidant systems.

In living organism, excessive free radicals or oxidative damage which occur as a result of deficient antioxidant defensive mechanisms by the effect of endogenous and exogenous factors, influences especially developmental steps of chemically induced cancers. In our study, plasma malondialdehyde level (MDA) as an indicator of lipid peroxidation, erythrocyte glutathione (GSH) level as an indicator of antioxidant state, glutathione reductase (GSH-Red), glutathione peroxidase (GSH-Px), glutathione-S-transferase (GST) as an antioxidant enzymes and plasma vitamin E level were detected in patients with prostate cancer (21 males; age, 69.4 +/- 4.8 years) before and after three months of antiandrogenic therapy with goserelin acetate as luteinizing hormone releasing hormone (LHRH) analogue. Healthy people evaluated as a control group (20 males; age, 63.7 +/- 3.9). Erythrocyte GSH levels, the activities of GSH-Red and GSH-Px and plasma vitamin E levels were found significantly low in patients with prostate cancer when compared with the healthy subjects (p < 0.01, p < 0.05, p < or = 0.001 and p < or = 0.001 respectively). Plasma MDA level and erythrocyte GST activity of patient group were significantly higher than the levels of control group (p < or = 0.001 and p < or = 0.001 respectively). After antiandrogenic therapy erythrocyte GSH level, GSH-Red, GSH-Px activity and plasma vitamin E level were found unchanged. Significant decrease in plasma MDA level and significant increase in erythrocyte GST activity were detected in patient group (p < 0.05 and p < or = 0.01 respectively). The study has revealed the shift in the oxidant-antioxidant balance towards oxidative state in patients with metastatic prostate cancer. Our results showed that antiandrogenic therapy increased in GST activity, decreased in lipid peroxidation.

Decrease in mitochondrial oxidative protein damage parameters in the streptozotocin-diabetic rat.

BACKGROUND: Many authors have shown that hyperglycemia leads to an increase in oxidative protein damage in diabetes. The aim of this study was to reveal the susceptibility of mitochondria from liver, pancreas, kidney, and skeletal muscle of diabetic Sprague-Dawley rats, a model of type 1 diabetes, to oxidative protein damage. METHODS: Mitochondrial fractions were obtained by differential centrifugation. To show the effect of hyperglycemia in promoting oxidative protein damage, we determined mitochondrial protein carbonyl, total thiol, nitrotyrosine, advanced oxidation protein products, and lipid hydroperoxide levels. The levels of the studied markers, except nitrotyrosine, were determined by colorimetric methods. Nitrotyrosine levels were measured by ELISA. All values were compared with those of the controls by using the Mann-Whitney U-test. RESULTS: Nitrotyrosine and lipid hydroperoxide levels were decreased and other parameters were not changed in liver mitochondria of diabetic rats. Protein carbonyl, nitrotyrosine, advanced oxidation protein products, and lipid hydroperoxide levels were decreased and total thiol levels were not changed in pancreas mitochondria of diabetic rats. Only advanced oxidation protein products and lipid hydroperoxide levels were decreased in kidney mitochondria of diabetic rats. The levels of the same parameters were not significantly different in muscle mitochondria of diabetic rats. CONCLUSIONS: The decrease in mitochondrial oxidative protein damage in diabetes may correspond to either an increase in antioxidant defense mechanisms or a different adaptive response of the cells to the increased extramitochondrial oxidative stress in diabetes. The mitochondrial oxidative protein damage-lowering mechanisms in diabetes remain to be clarified.

Increased formation of 8-hydroxy-2'-deoxyguanosine in peripheral blood leukocytes in bladder cancer.

INTRODUCTION: Reactive oxygen species-induced damage to DNA plays a major role in carcinogenesis. METHODS: In order to estimate the level of oxidative damage in bladder cancer, 8-hydroxy-2'-deoxyguanosine (8-OHdG) was determined in DNA isolated from peripheral blood leukocytes of healthy adults and patients with superficial transitional cell carcinoma. Patients with transitional cell carcinoma of the bladder and control individuals were similar in age. In this study, the level of 8-OHdG in DNA in male subjects was measured by the high-performance liquid chromatography-electrochemical detector method. RESULTS: The 8-OHdG levels in DNA from leukocytes of bladder cancer patients were significantly higher than those in controls. CONCLUSION: Reduction of oxidative stress is thought to be a very important measure for primary prevention of bladder cancer.

O(6)-methylguanine DNA methyltransferase activity in diabetic patients.

In the present study, we evaluated O(6)-methylguanine-DNA methyltransferase (MGMT) activity in diabetic patients. The study was performed on 27 patients with Type 1 diabetes, and 42 with Type 2 diabetes. Patients with complications were excluded from the study. 36 non-diabetic volunteers, non-smokers who do not consume alcoholic beverage, were chosen from the medical staff as control subjects. MGMT activity was measured by the transfer of radiolabeled methyl groups from a prepared methylguanine-DNA substrate to the enzyme fraction of leukocyte extract. Leukocyte MGMT activity was significantly reduced in both Type 1 and Type 2 diabetes patients as compared with control subjects (P<0.001). The present study demonstrates decreased MGMT activity in leukocytes from patients with Type 1 and Type 2 diabetes.