Biomarkers of enzymatic and non-enzymatic antioxidative defense in type 2 diabetes mellitus - comparative analysis

Cilj naše studije bio je odrediti međusobne odnose između „prve", neenzim-ske, te „druge", enzimske crte antioksidacijske zaštite u bolesnika s šećernom bolesti tipa 2 i očitovanim kardiovaskularnim komplikacijama. Drugi je cilj bio utvrditi odnose između prooksidacijskih (lipidni status) i antioksidacijskih parametara u ispitivanih bolesnika. Materijali i metode: U našu je studiju parova bilo uključeno ukupno 117 bolesnika s šećernom bolesti tipa (69 sa, te 48 bez kardiovaskularnih komplikacija) i 42 zdrava ispitanika. Određivani su sljedeći antioksidacijski enzimski parametri: eritrociti, Cu, Zn-SOD, glutation-peroksidaza (GPx) i glutation-reduk-taza (GR), kao i ukupni antioksidacijski status (engl. total antioxidant status, TAS), te bilirubin, mokraćna kiselina, ukupni proteini, albumin i haptoglobin. Enzimski antioksidacijski parametri i TAS analizirani su pomoću komercijalnih testova tvrtke RandoxLtd, V. Britanija, koji se temelje na spektrofotometrij-skim metodama, dok su ostali neenzimski i lipidni parametri određeni standardnim laboratorijskim metodama. Rezultati: U odnosu na zdrave ispitanike, bolesnici s šećernom bolesti tipa 2 i kardiovaskularnim komplikacijama imali su značajno niže vrijednosti en-zimskih antioksidansa (P < 0,001) i više vrijednosti ukupnog bilirubina (P = 0,050), mokraćne kiseline (P < 0,001) i haptoglobina (P < 0,001). Slaba je pozitivna korelacija utvrđena između SOD i GPx (R = 0,289, P = 0,028) te između SOD i GR (R = 0,259, P = 0,045), a slaba negativna korelacija zabilježena je između GPx i mokraćne kiseline (R = - 0,35, P = 0,009) te GPx i ukupnog bilirubina (R = - 0,40, P = 0,018). TAS je slabo korelirao s trigliceridima (R = 0,32, P = 0,037), a GPx i GR su korelirali s HDL-kolesterolom (R = 0,457, P = 0,007; te R = 0,466, P = 0,001). Zaključci: Temeljem dobivenih rezultata može se zaključiti da bolesnici s šećernom bolesti tipa 2 imaju značajno promijenjenu antioksidacijsku zaštitu, uz različiti stupanj neravnoteže između skupa neenzimskih tvari i aktivnosti enzimskih antioksidanasa, koja ovisi o tome jesu li se kardiovaskularne komplikacije pojavile ili ne.The objective of our study was to determine the interrelations between the "first", non-enzymatic, and the "second", enzymatic line of antioxidant defense in patients with type 2 diabetes mellitus and manifested cardiovascular complications. The second aim was to determine the relations between pro-oxidant (lipid status) and antioxidant parameters in patients under observation. Methods: In our case-control study, a total of 117 type 2 diabetic patients (69 with and 48 without cardiovascular complications) and 42 healthy subjects were included. Antioxidant enzymatic parameters: erythrocyte, Cu,Zn-SOD, glutathione peroxidase (GPx) and glutathione reductase (GR), as well as total antioxidant status (TAS), bilirubin, uric acid, total proteins, albumin and haptoglobin were determined. The enzymatic antioxidant parameters and TAS were analyzed using commercial tests manufactured by Randox Ltd. UK, based on spectrophotometer methods, while the other non-enzymatic and lipid parameters were determined by standard laboratory methods. Results: In relation to healthy subjects, type 2 diabetics with cardiovascular complications had significantly lower values of enzymatic antioxidants (P < 0.001), and higher values of total bilirubin (P = 0.050), uric acid (P < 0.001) and haptoglobin (P < 0.001). Weak positive correlation was found between SOD and GPx (R = 0.289, P = 0.028) and between SOD and GR (R = 0.259, P = 0.045), while weak negative correlation was obtained between GPx and uric acid (R = -0.35, P = 0.009), GPx and total bilirubine (R = -0.40, P = 0.018). TAS correlated weakly with triglycerides (R = 0.32, P = 0.037), while GPx and GR correlated with HDL-cholesterol (R = 0.457, P = 0.007; and R = 0.466, P = 0.001). Conclusions: Based on the obtained results, it may be concluded that type 2 diabetic patients have significantly modified antioxidant defense, with a varying degree of imbalance between the "pool" of non-enzymatic substances and the activity of enzymatic antioxidants, which depends on whether they have or not manifested cardiovascular complications

Oxidative Stress and DNA Damage in Peripheral Blood Mononuclear Cells from Normal, Obese, Prediabetic and Diabetic Persons Exposed to Thyroid Hormone In Vitro

Diabetes, a chronic group of medical disorders characterized byhyperglycemia, has become a global pandemic. Some hormones may influence the course and outcome of diabetes, especially if they potentiate the formation of reactive oxygen species (ROS). There is a close relationship between thyroid disorders and diabetes. The main objective of this investigation was to find out whether peripheral blood mononuclear cells (PBMCs) are more prone to DNA damage by triiodothyronine (T3) (0.1, 1 and 10 μM) at various stages of progression through diabetes (obese, prediabetics, and type 2 diabetes mellitus—T2DM persons). In addition, some biochemical parameters of oxidative stress (catalase-CAT, thiobarbituric acid reactive substances—TBARS) and lactate dehydrogenase (LDH) were evaluated. PBMCs from prediabetic and diabetic patients exhibited increased sensitivity for T3 regarding elevated level of DNA damage, inhibition of catalase, and increase of TBARS and LDH. PBMCs from obese patients reacted in the same manner, except for DNA damage. The results of this study should contribute to a better understanding of the role of thyroid hormones in the progression of T2DM

How the sialylation level of serum N-acetyl-β-D-glucosaminidase a form in type 1 diabetes mellitus influences its activity?

It has been verified that serum N-acetyl-β-D-glucosaminidase (NAG) activity is elevated in diabetes, but there are no reports about changes of the sialic acid (SA) content in the carbohydrate parts of NAG A form and its influence on total NAG activity changes in type 1 diabetes mellitus patients without and with secondary complications. NAG A forms were isolated, purified and characterized from the serum of 81 IDDM patients with and without secondary complications (retinopathy, polyneuropathy and nephropathy) and 25 healthy persons. The content of α-2,6-bound SA and isoenzyme patterns of purified A form, total NAG and A form activities were determined. In all diabetic groups, A form sialylation levels were 2-3.5 times lower compared to control, while their acidities (fractions with pI 4.25-5.1) increased, particularly with progression of secondary complications. Total serum NAG activities and percentages of A form were significantly higher (P<0.001) in all diabetic groups and negatively correlated with the α-2,6-bound SA content of the A form. In addition, they decreased as secondary diabetic complications became more complex. Observed changes could be the consequence of structural changes in the A form due to significant increase in its acidity, i.e. negative charge which originate from groups other than SA. [Projekat Ministarstva nauke Republike Srbije, br. 172049

Effect of alcohol on insulin secretion and viability of human pancreatic islets

Introduction/Objective. There are controversial data in the literature on the topic of effects of alcohol on insulin secretion, apoptosis, and necrosis of the endocrine and exocrine pancreas. The goal of this research was to determine how alcohol affects the insulin secretion and viability of human adult pancreatic islets in vitro during a seven-day incubation. Methods. Human pancreatic tissue was digested with Collagenase XI, using a non-automated method. Cultures were incubated in Roswell Park Memorial Institute (RPMI) medium containing alcohol (10 μl of alcohol in 100 ml of medium). Insulin stimulation index (SI) and viability of the islets were determined on the first, third, and seventh day of cultivation. Results. Analysis of the viability of the islets showed that there wasn’t significant difference between the control and the test group. In the test group, viability of the cultures declined with the time of incubation. SI of the test group was higher compared to the control group, by 50% and 25% on the first and third day of cultivation, respectively. On the seventh day, insulin secretion was reduced by 25%. The difference was not statistically significant (p > 0.05). In the test group, significant decline in insulin secretion was found on the third and seventh day of incubation (p ≤ 0.05). Conclusion. Alcohol can increase or decrease insulin secretion of islets cultures, which may result in an inadequate response of pancreatic β-cells to blood glucose, leading to insulin resistance, and increased risk of developing type 2 diabetes. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 41002

Effects of total fibre or resistant starch-rich diets within lifestyle intervention in obese prediabetic adults

Starting from the evidence-based health benefits that resistant starch (RS) shows when added to the diet, our aim in this study was to evaluate the effects of increased fibre intake with two different levels of RS coming from regular daily consumed foods on normalization of glycaemia within lifestyle intervention in the population with risk factors for developing diabetes. Study included 47 overweight and obese men and women with disordered glucoregulation and dyslipidaemia, aged between 45-74, divided into RS and Fibre group. Participants were subjected to the lifestyle and dietary intervention with low-fat and high-fibre (> 25 g/day) diet for 12 months and were offered two different dietary advices aimed at increasing total fibre intake in Fibre group and at increasing RS intake in RS group. The intake of macronutrients and total fibre was similar between groups at the end of the study, but achieved RS intake was two times higher in the RS group. Decrease in total cholesterol and non-HDL-cholesterol was more pronounced in RS group in comparison with Fibre group (p = 0.010, p = 0.031, respectively), whereas in Fibre group, a more pronounced effect on glucoregulation was observed: significant fall in glycaemia after 2-h oral glucose tolerance test (7.93 vs 6.96 mmol/L, p = 0.034). At the end of the study, RS-rich diet failed to affect glycaemic control in prediabetic obese individuals in contrast to the regular fibre-rich diet, which indicated that fibre profile could be an important determinant of the effect of dietary intervention

Pre- and postoperative characteristics of metabolic syndrome in patients with colorectal cancer

The pathological mechanisms that link the metabolic syndrome (MS) and colorectal cancer (CRC) are most probably related to abdominal obesity and insulin resistance. This study aimed to assess the relationship between MS and its clinical characteristics, with CRC. We investigated the changes in the appearance of MS features three months after surgical treatment, and its relationship with the concentration of tumor and inflammation markers. The retrospective cohort study was performed on 193 patients who were diagnosed with CRC and consequently surgically treated (at the Department of General Surgery, Clinical Hospital Center “Bežanijska kosa”, Belgrade). The included patients were divided into two groups based on the presence of MS. Body mass index (BMI), waist circumference, blood pressure, blood glucose, triglycerides (TG), high density lipoproteins - cholesterol (HDL-C), carcinoembryonic antigen (CEA), α-fetoprotein (AFP), carbohydrate antigen 19-9 (CA 19-90) and C-reactive protein (CRP) were analyzed at the time when the CRC diagnosis was made and three months after surgery. We observed a significant decrease in the number of patients with MS three months postoperatively compared to the number of patients in the preoperative period (106 versus 81; p<0.001). CRP levels were significantly decreased postoperatively compared to the preoperative period in patients with MS (p<0.001). AFP concentrations were significantly decreased (p<0.001), while CEA and CA 19-9 were significantly increased postoperatively compared to preoperatively (p<0.001, p<0.001). Further studies should be conducted in order to examine the influence of MS and its characteristics solely on CRC prognosis and its overall effect on CRC treatment

Characterisation of dietary fibre components in cereals and legumes used in Serbian diet

The typical Serbian diet is characterised by high intake of cereal products and also legumes are often used. The content of total fibre as well as certain fibre fractions was determined in cereals, cereal products, and cooked legumes. The content of total fibre in cooked cereals and cereal products ranged from 2.5 to 20.8 g/100 g, and in cooked legumes from 14.0 to 24.5 g/100 g (on dry matter basis). Distribution of analysed fibre fractions and their quantities differed significantly depending on food groups. Fructans and arabinoxylans were the most significant fibre fractions in rye flakes, and beta-glucan in oat flakes, cellulose and resistant starch were present in significant amounts in peas and kidney beans. When the size of regular food portions was taken into consideration, the best sources of total dietary fibre were peas and kidney beans (more than 11 g/serving). The same foods were the best sources of cellulose (4.98 and 3.56 g/serving) and resistant starch (3.90 and 2.83 g/serving). High intake of arabinoxylans and fructans could be accomplished with cooked wheat (3.20 g and 1.60 g/serving, respectively). Oat (1.39 g/serving) and barley flakes (1.30 g/serving) can be recommended as the best sources of beta-glucan

Influence of the purification of human adult pancreatic islets on insulin secretion

Background/Aim. The most effective method for human adult pancreatic islets purification is density-gradient centrifugation. The aim of this study was to analyze the effects of non-automated purification on preservation of functional capacity of human adult pancreatic islet cells. Methods. Human pancreata were obtained after pancreatectomy in the patients with chronic pancreatitis or benign tumors. Pancreatic islets were purified by non-automated method in discontinuous Ficoll density gradient. The samples were divided in 2 fractions: purified (P) and non-purified (NP) cultures. Islets were stained with diphenyl-thiocarbazone. The efficiency of separation was determined by comparing percentage of stained cells in P and NP cultures on day 1, 3 and 7 of shortterm cultivation. Glucose-stimulated insulin secretion was expressed as stimulation index (SI). Results. The results obtained showed a statistically significant difference (p &lt; 0.01) between P and NP cultures. P cultures had higher percentages of stained cells (70.43 ± 3.97%, 73.77 ± 4.22% and 71.34 ± 4.69% on the first, third and seventh day of cultivation, respectively) than NP cultures (53.68 ± 1.71%, 57.14 ± 3.94% and 43.97 ± 4.56%, respectively). P cultures had higher values of SI for the first, third and seventh day of cultivation than NP cultures (0.45 ± 0.08, 0.80 ± 0.21, 1.28 ± 0.15 and 0.46 ± 0.10, 0.752 ± .0.16, 0.76 ± 0.11 for P and NP cultures respectively). The difference was statistically significant on day seven (p = 0.01). Conclusion. Although during purification process islets were exposed to a number of insults that might result in cellular damage and functional impairment, our assessments showed that islets in P cultures preserved their functional capacity better than islets in NP cultures, since they had greater insulin secretion