Micronutrients and antioxidants in the progression of diabetes

How Diabetes and Other Comorbidities of Elderly Patients and Their Treatment Influence Levels of Glycation Products

Medical care for geriatric patients is a great challenge, mainly due to various overlapping deficits relevant to numerous coexisting diseases, of which the most common are diabetes mellitus and atherosclerosis. In the case of diabetes, the glycation process is intensified, which accelerates atherosclerosis development and diabetic complications. Our goal was to investigate the relationship between the classical biochemical parameters of diabetes and atherosclerosis, as well as parameters which may indicate a nephropathy, and the parameters strictly related to glycation, taking into account the pharmacological treatment of patients. Methods: We analyzed the patients’ serum concentrations of fluorescent glycation product—pentosidine, concentrations of soluble receptors for advanced glycation products (sRAGE), lipoprotein receptor-1 (LOX-1), galectin 3 (GAL3), scavenger receptor class A (SR-A), and scavenger receptor class B (SR-BI), as well as the level of lipid peroxidation and free amine content. Among the identified correlations, the most interesting are the following: sRAGE with triglycerides (r = 0.47, p = 0.009), sRAGE with SR-BI (r = 0.47, p = 0.013), SR-BI with LOX-1 (r = 0.31, p = 0.013), and SR-BI with HDL (r = −0.30, p = 0.02). It has been shown that pentosidine and reactive free amine contents are significantly higher in elderly patients with ischemic heart disease. Pentosidine is also significantly higher in patients with arterial hypertension. Malondialdehyde turned out to be higher in patients with diabetes mellitus type 2 that was not treated with insulin or metformin than in those treated with both medications (p = 0.052). GAL3 was found to be lower both in persons without diabetes and in diabetics treated with metformin (p = 0.005). LOX-1 was higher in diabetic patients not treated with metformin or insulin, and lowest in diabetics treated with both insulin and metformin, with the effect of metformin reducing LOX-1 levels (p = 0.039). Our results were the basis for a discussion about the diagnostic value in the clinical practice of LOX-1 and GAL3 in geriatric patients with diabetes and also provide grounds for inferring the therapeutic benefits of insulin and metformin treatment.

A Cross-Sectional Study of the Effects of Physical Activity and Nutrient Intakes on Blood Glucose Control Rates in Middle-Aged and Elderly Diabetes Patients: Korean National Health and Nutrition Examination Survey 2015-2017

This study aimed to investigate factors affecting blood glucose control among middle-aged and older diabetic patients taking medications or receiving insulin therapy. In 2015–2017 data obtained from the Korean National Health and Nutrition Examination Survey (KNHANES), 1257 patients with diabetes were divided into a controlled group and an uncontrolled group based on blood glucose levels (cutoff ≥126 mg/dL). After adjusting for confounding factors, the BMI, total cholesterol level, and triglycerides level of the uncontrolled group were significantly higher than the controlled group. The total amount of moderate-intensity activity in controlled patients was significantly higher than that of the controlled group. Total energy, fat, saturated fatty acids, and cholesterol intakes were found to be significantly higher in the uncontrolled than controlled group. Intakes of calcium, phosphorus, potassium, riboflavin, niacin, and vitamin C were significantly lower in the uncontrolled than controlled group. Adequate nutrition intake and physical activity of patients undergoing diabetes therapy are required for effective blood glucose management for both diabetic drug and insulin therapies.

Secondary Metabolites in the Treatment of Diabetes Mellitus: A Paradigm Shift

Diabetes mellitus (DM) is a chronic, polygenic and non-infectious group of diseases that occurs due to insulin resistance or its low production by the pancreas and is also associated with lifelong damage, dysfunction and collapse of various organs. Management of diabetes is quite complex having many bodily and emotional complications and warrants efficient measures for prevention and control of the same. As per the estimates of the current and future diabetes prevalence, around 425 million people were diabetic in 2017 which is anticipated to rise up to 629 million by 2045. Various studies have vaguely proven the fact that several vitamins, minerals, botanicals and secondary metabolites demonstrate hypoglycemic activity in vivo as well as in vitro. Flavonoids, anthocyanin, catechin, lipoic acid, coumarin metabolites, etc. derived from herbs were found to elicit a significant influence on diabetes. However, the prescription of herbal compounds depend on various factors, including the degree of diabetes progression, comorbidities, feasibility, economics as well as their ADR profile. For instance, cinnamon could be a more favorable choice for diabetic hypertensive patients. Diabecon®, Glyoherb® and Diabeta Plus® are some of the herbal products that had been launched in the market for the favorable or adjuvant therapy of diabetes. Moreover, Aloe vera leaf gel extract demonstrates significant activity in diabetes. The goal of this review was to inscribe various classes of secondary metabolites, in particular those obtained from plants, and their role in the treatment of DM. Recent advancements in recognizing the markers which can be employed for identifying altered metabolic pathways, biomarker discovery, limitations, metabolic markers of drug potency and off-label effects are also reviewed.

Socio-demographic patterning of the individual-level double burden of malnutrition in a rural population in South India: a cross-sectional study

BACKGROUND

The double burden of malnutrition is the co-occurrence of undernutrition (e.g. underweight, stunting, and micronutrient deficiencies) and over-nutrition (e.g. obesity, type 2 diabetes, and cardiovascular disease) at the population, household, or individual level. The objectives of this study were to determine the extent and determinants of individual-level co-morbid anemia and overweight and co-morbid anemia and diabetes in a population in rural Tamil Nadu, South India.

METHODS

We undertook a cross-sectional study of adults (n = 753) in a rural region of Tamil Nadu, South India. A survey assessed socio-demographic factors, physical activity levels, and dietary intake. Clinical measurements included body-mass index, an oral glucose tolerance test, and blood hemoglobin assessments. Multivariable logistic regression analyses were used to determine associations between risk factors and two co-morbid double burden pairings: (1) anemia and overweight, and (2) anemia and diabetes.

RESULTS

Prevalence of co-morbid anemia and overweight was 23.1% among women and 13.1% among men. Prevalence of co-morbid anemia and diabetes was 6.2% among women and 6.3% among men. The following variables were associated with co-morbid anemia and overweight in multivariable models [odds ratio (95% confidence interval)]: female sex [2.3 (1.4, 3.85)], high caste [3.2 (1.34, 7.49)], wealth index [1.1 (1.00, 1.12)], rurality (0.7 [0.56, 0.85]), tobacco consumption [0.6 (0.32, 0.96)], livestock ownership [0.5 (0.29, 0.89)], and energy-adjusted meat intake [1.8 (0.61, 0.94)]. The following variables were associated with co-morbid anemia and diabetes in multivariable models: age [1.1 (1.05, 1.11)], rurality [0.8 (0.57, 0.98)], and family history of diabetes [4.9 (1.86, 12.70).

CONCLUSION

This study determined the prevalence and factors associated with individual-level double burden of malnutrition. Women in rural regions of India may be particularly vulnerable to individual-level double burden of malnutrition and should be a target population for any nutrition interventions to address simultaneous over- and undernutrition.

Scavenging of reactive oxygen and nitrogen species with nanomaterials

Reactive oxygen and nitrogen species (RONS) are essential for normal physiological processes and play important roles in cell signaling, immunity, and tissue homeostasis. However, excess radical species are implicated in the development and augmented pathogenesis of various diseases. Several antioxidants may restore the chemical balance, but their use is limited by disappointing results of clinical trials. Nanoparticles are an attractive therapeutic alternative because they can change the biodistribution profile of antioxidants, and possess intrinsic ability to scavenge RONS. Herein, we review the types of RONS, how they are implicated in several diseases, and the types of nanoparticles with inherent antioxidant capability, their mechanisms of action, and their biological applications.

The Effects of Supplementary Mulberry Leaf (Morus alba) Extracts on the Trace Element Status (Fe, Zn and Cu) in Relation to Diabetes Management and Antioxidant Indices in Diabetic Rats

Mulberry leaves (Morus alba) have been used in folk medicine to mitigate symptoms of diabetes. The mulberry plant contains phenolic compounds that are able to decrease blood glucose concentration. Since various phenolics have antioxidant and metal binding properties, they can be used to alleviate oxidative stress and chelate trace elements involved in redox reactions. The aim of this study was to evaluate the effects of dietary supplementation with mulberry leaf extracts (acetone-water (AE) and ethanol-water (EE)) on the trace element status (Fe, Zn and Cu) in relation to diabetes management and antioxidant indices in high-fat diet-fed/STZ diabetic rats. The experiment was performed on 38 male Wistar rats with diabetes (induced by high-fat diet (HF) and streptozotocin injection) or the control fed with AIN-93M or high-fat diet. As a result, five experimental groups were used: (1) a healthy control group fed with AIN-93M; (2) an HF control group; (3) a diabetic HF group; (4) a diabetic HF + AE group (6 g/kg diet); (5) a diabetic HF + EE group (6 g/kg diet). The rats were fed with appropriate diets for 4 weeks. The content of trace elements (Fe, Zn and Cu) in the serum and tissues was measured by means of atomic absorption spectrometry (AAS). Biochemical analyses (glucose, TBARS, FRAP) were performed on the blood serum. It was shown that the AE decreased hepatic and renal Fe stores, while the EE increased hepatic Cu levels in diabetic rats and confirmed their ability to regulate the Fe and Cu status in diabetes. The results confirmed a significant hypoglycaemic and antioxidant potential of both mulberry leaf extracts in diabetic rats.

Comparative Study of Antidiabetic Activity and Oxidative Stress Induced by Zinc Oxide Nanoparticles and Zinc Sulfate in Diabetic Rats

In the current study, antidiabetic activity and toxic effects of zinc oxide nanoparticles (ZnO) were investigated in diabetic rats compared to zinc sulfate (ZnSO4) with particular emphasis on oxidative stress parameters. One hundred and twenty male Wistar rats were divided into two healthy and diabetic groups, randomly. Each major group was further subdivided into five subgroups and then orally supplemented with various doses of ZnO (1, 3, and 10 mg/kg) and ZnSO4 (30 mg/kg) for 56 consecutive days. ZnO showed greater antidiabetic activity compared to ZnSO4 evidenced by improved glucose disposal, insulin levels, and zinc status. The altered activities of erythrocyte antioxidant enzymes as well as raised levels of lipid peroxidation and a marked reduction of total antioxidant capacity were observed in rats receiving ZnO. ZnO nanoparticles acted as a potent antidiabetic agent, however, severely elicited oxidative stress particularly at higher doses.

Tobacco smoking, alcohol drinking, diabetes, low body mass index and the risk of self-reported symptoms of active tuberculosis: individual participant data (IPD) meta-analyses of 72,684 individuals in 14 high tuberculosis burden countries

BACKGROUND

The effects of multiple exposures on active tuberculosis (TB) are largely undetermined. We sought to establish a dose-response relationship for smoking, drinking, and body mass index (BMI) and to investigate the independent and joint effects of these and diabetes on the risk of self-reported symptoms of active TB disease.

METHODS AND FINDINGS

We analyzed 14 national studies in 14 high TB-burden countries using self-reports of blood in cough/phlegm and cough lasting > = 3 weeks in the last year as the measures of symptoms of active TB. The random effect estimates of the relative risks (RR) between active TB and smoking, drinking, diabetes, and BMI<18.5 kg/m2 were reported for each gender. Floating absolute risks were used to examine dyads of exposure. Adjusted for age and education, the risks of active TB were significantly associated with diabetes and BMI<18.5 kg/m2 in both sexes, with ever drinking in men and with ever smoking in women. Stronger dose-response relationships were seen in women than in men for smoking amount, smoking duration and drinking amount but BMI<18.5 kg/m2 showed a stronger dose-response relationship in men. In men, the risks from joint exposures were statistically significant for diabetics with BMI<18.5 kg/m2 (RR = 6.4), diabetics who smoked (RR = 3.8), and diabetics who drank alcohol (RR = 3.2). The risks from joint risk factors were generally larger in women than in men, with statistically significant risks for diabetics with BMI<18.5 kg/m2 (RR = 10.0), diabetics who smoked (RR = 5.4) and women with BMI<18.5 kg/m2 who smoked (RR = 5.0). These risk factors account for 61% of male and 34% of female estimated TB incidents in these 14 countries.

CONCLUSIONS

Tobacco, alcohol, diabetes, and low BMI are significant individual risk factors but in combination are associated with triple or quadruple the risk of development of recent active TB. These risk factors might help to explain the wide variation in TB across countries.

Effect of Ginkgo leaf parenteral solution on blood and cochlea antioxidant and immunity indexes in OM rats

Oxidative stress is involved in the development and progression of otitis media (OM). In this study, we investigated the effect of Ginkgo leaf parenteral solution on blood and cochlea antioxidant and immunity indexs in OM rats. In OM model rats, blood and cochlea malondialdehyde (MDA), nitric oxide (NO), tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8) and interleukin-10 (IL-10) levels were significantly increased, whereas antioxidant enzymes activities (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and glutathione reductase (GR)) were significantly decreased compared with normal rats. Treatment with Ginkgo leaf parenteral solution restored the altered parameters in a dose-dependent manner. We conclude that Ginkgo leaf parenteral solution confers protection against oxidative injuries in OM rats by increasing activities of antioxidants and immunity, suggesting a potential drug for the prevention and therapy of OM.

Determination of in vitro antidiabetic effects, antioxidant activities and phenol contents of some herbal teas

In this research, some herbal teas and infusions traditionally used in the treatment of diabetes in Turkey, have been studied for their antidiabetic effects on in vitro glucose diffusion and phenolic contents and antioxidant activities. Ten aqueous herbal tea extracts were examined using an in vitro method to determine their effects on glucose movement across the gastrointestinal tract. Total phenol content of herbal teas was analyzed by Folin-Ciocalteu's procedure. Antioxidant activities of herbal teas were evaluated by the effect of extracts on DPPH radical and hydrogen peroxide scavenging. Antioxidant activity was defined as the amount of the sample to decrease the initial DPPH concentration by 50% as efficient concentration, EC50. Antiradical activity [AE] was calculated as 1/EC50. Values were evaluated statistically. Results support the view that none of the herbal teas showed antidiabetic effect on glucose diffusion using in vitro model glucose absorption. Teas were arranged in the order of green tea > peppermint > thyme > black tea > relax tea > absinthium > shrubby blackberry > sage > roselle > olive leaves according to their total phenol contents. Among ten herbal teas, green tea had the highest hydrogen-donating capacity against to DPPH radical. Ranking of the herbal teas with respect to their DPPH radical scavenging activity were green tea > peppermint > black tea > thyme > relax tea > absinthium > roselle > olive leaves > sage > shrubby blackberry. It was determined that adding flavoring substances such as lemon, bergamot, clove and cinnamon, which are commonly used in preparation of black tea in Turkey resulted to have synergistic effect on total antioxidant activities of black and peppermint teas. The highest hydrogen peroxide inhibition value (65.50%) was obtained for green tea at a 250 microl/ml concentration. The H2O2 scavenging activity of herbal teas decreased in the order green tea > peppermint > relax tea > black tea > thyme > olive leaves > sage > absinthium > shrubby blackberry > roselle. In particular, their phenolic compounds and antioxidant activities may be useful for meal planning in type 2 diabetes. They could contribute to sustain plasma antioxidant level because antioxidants present in plants and herbs prevent the development of vascular diseases seen in type 2 diabetes.

Antioxidant activity relates to plant part, life form and growing condition in some diabetes remedies

Selection, collection and preparation of 35 plant species used by traditional healers in the boreal regions of Canada for treatment of the symptoms of diabetes were supported empirically by antioxidant activity of the plants. Because antioxidants fluctuate with growth parameters and environmental factors, these remedies were evaluated in relation to the affect of plant part, life form and growing condition on the level of activity. The parts used here more frequently as medicines were roots and bark. Activity (IC(50)) of the bark extracts used medicinally averaged to 21.38+/-3.84 ppm while root extracts used medicinally had an IC(50) of 185.11+/-32.18 ppm in a free radical DPPH assay. In contrast the analysis of extracts of overall parts (medicinal or not) in these species found leaves and bark to have the least activity (112.22+/-30.63 ppm and 123.02+/-21.13 ppm, respectively). The highest activity was found in tree extracts (24.88+/-3.32 ppm) as compared to herbs and shrubs, and increased activity was found in plant extracts from growing conditions of decreased water/fertility. The antioxidant activity of these traditional plant remedies have the potential to be partially deduced through environment signals interpreted by the traditional herbalist.

The overlap of overweight and anaemia among women in three countries undergoing the nutrition transition

OBJECTIVE

To compare the odds of anaemia in overweight and obese (OVWT) (body mass index (BMI) > or =25) versus non-overweight (non-OVWT) (BMI<25) women in three countries at different stages of the nutrition transition.

DESIGN

Analysis of cross-sectional data.

SETTING

Nationally representative data from Mexico (1998 National Nutrition Survey), Peru and Egypt (2000 Demographic and Health Surveys) were analyzed.

SUBJECTS

Data from non-pregnant women ages 18-49 years were used.

ANALYSIS

Logistic regression was used to test whether the odds of anaemia differed by BMI category, controlling for sociodemographic factors.

RESULTS

More than half of the women were OVWT in all three countries and the prevalence of OVWT reached 77% in Egypt. Anaemia prevalence was similar across countries (28, 31 and 23% in Egypt, Peru and Mexico respectively). In Egypt, OVWT women had significantly lower odds of anaemia than non-OVWT women (OR=0.78, 95% CI: 0.68, 0.90). Similar results were found in Peru, but the difference was smaller in magnitude (OR=0.83, 95% CI: 0.71, 0.96). In Mexico, there were no differences in the odds of anaemia by BMI group.

CONCLUSIONS

These findings show that the iron needs of OVWT women in developing countries are not necessarily being met. The intakes of other micronutrients might also be insufficient. Diet quality remains an important issue even among women with sufficient energy intakes.

Oxidant and antioxidant levels in children with acute otitis media and tonsillitis: a comparative study

OBJECTIVE

Recurrent episodes of acute otitis media (AOM) and acute tonsillitis (AT) are a common problem in infectious disorders during childhood and are major cause of morbidity in children. The organism maintains defense systems including nonenzymatic antioxidants such as Vitamins A, E and C and reduced glutathione (GSH) against reactive oxygen species (ROS). In the present study, lipid peroxidation status and nonenzymatic antioxidant capacity were investigated in children with AOM and AT. Our aim was to compare the lipid peroxidation and responses of the body's antioxidant status in the closely associated infections such as AOM and acute tonsillitis.

METHODS

The study included 23 (14 males, 9 females) children with AOM, 27 (14 males, 13 females) with AT and 29 (16 males, 13 females) healthy control subjects. The ages of the study and control subjects were between 2 and 7 years. Serum beta-carotene, retinol, Vitamin E, Vitamin C, and whole blood malondialdehyde (MDA) (as an indicator of lipid peroxidation) and GSH levels were studied in all subjects.

RESULTS

There was a statistically significant difference between the groups for all parameters (P<0.05). All of the antioxidant vitamins such as beta-carotene, retinol, Vitamin E, and Vitamin C levels were observed to be significantly decreased in the both patient groups. Nevertheless, GSH levels were also decreased in the patient groups. MDA levels were found to be higher in children with AOM and AT than in the healthy control subjects. When compared the AOM and AT groups, there was statistically significant difference between the groups for whole blood MDA (P<0.05).

CONCLUSION

Even though they seem to react in a similar way against ROS, in the cases of AOM and AT, it is possible to see the different approaches in these tissues for the oxidative stress.

Comparison of anti-hyperglycemic effect amongst vanadium, molybdenum and other metal maltol complexes

A wide variety of vanadium-containing complexes have been tested, both in vivo and in vitro, as possible therapeutic agents for the oral treatment of type 2 diabetes mellitus. None so far has surpassed bis(maltolato)oxovanadium(IV) (BMOV) for glucose- and lipid-lowering in an orally available formulation. Ligand choice is clearly an important factor in pharmacological efficacy of vanadium compounds as insulin enhancing agents. In this study, we kept the ligand and dose the same, varying instead the metal ion bound to the maltolato ligand in a series of binary complexes of neutral charge. A requirement for vanadyl ion as the metal ion of choice was apparent; no other metal ion tested served as a suitable substitute. Amongst [MoO(2)](2+), Co(II), Cu(II), Cr(III), and Zn(II), only [MoO(2)](2+) and Co(II) showed any hypoglycemic activity at the ED(50) dose for bis(maltolato)oxovanadium(IV), 0.6 mmolkg(-1) by oral gavage in streptozotocin (STZ)-diabetic rats within 72 h of administration of compound.

Alterações gastrointestinais no diabetes mellitus: estresse oxidativo e fluxo sangüíneo da artéria mesentérica - estudo experimental

RACIONAL: Os sintomas gastrointestinais são freqüentes no diabetes mellitus e podem estar relacionados com o estresse oxidativo, que é definido pelo desequilíbrio entre os sistemas pró-oxidante e o antioxidante. OBJETIVO: Avaliar algumas das alterações gastrointestinais no modelo de diabetes mellitus, como o estresse oxidativo no estômago e no fígado de animais diabéticos e o fluxo sangüíneo na artéria mesentérica superior em diferentes tempos de estudo. MATERIAL E MÉTODOS: Os parâmetros utilizados para verificar o estresse oxidativo no fígado e no estômago foram a mensuração da lipoperoxidação, através das técnicas das substâncias reativas ao ácido tiobarbitúrico e da quimiluminescência e a avaliação da atividade das enzimas antioxidantes catalase, superóxido dismutase e glutationa transferase. Utilizaram-se ratos machos Wistar, pesando entre 250-350 g, que foram divididos em quatro grupos: grupo I - 7 dias de diabetes, grupo II- 30 dias de diabetes, grupo III - 60 dias de diabetes e grupo IV - 90 dias de diabetes. O diabetes foi induzido por administração de estreptozotocina 70 mg/kg intraperitonialmente. RESULTADOS: Houve aumento significativo na lipoperoxidação no estômago e no fígado de animais diabéticos somente no tempo de 90 dias. No estômago, foi encontrada significativa diminuição na atividade das enzimas antioxidantes catalase e glutationa transferase. No fígado, somente a enzima glutationa transferase apresentou diminuição significativa. Houve aumento no fluxo da artéria mesentérica superior dos animais diabéticos com 90 dias, quando comparados aos animais-controle. CONCLUSÕES: É possível supor que o aumento no estresse oxidativo no estômago e no fígado e a alteração no fluxo sangüíneo da artéria mesentérica superior sejam influenciados pelo tempo de diabetes e pela hiperglicemia encontrada nos animais estudados, o que determinaria as alterações gastrointestinais.

Probucol restores the defective leukocyte–endothelial interaction in experimental diabetes

Defective leukocyte-endothelial interactions have been observed in experimental type 1 diabetes. One of the mechanisms involved in the late complications of diabetes mellitus is the formation of free radicals species. Antioxidant treatment has been demonstrated to have beneficial effects on the complications observed in this pathology. Using intravital microscopy to visualize venules of the internal spermatic fascia, we demonstrated that the defective leukocyte-endothelial interactions in alloxan-induced diabetic rats could be corrected by probucol treatment. The defects were quantitated by the number of leukocytes rolling along the venular endothelium, sticking to the venular wall after topical application of zymosan-activated plasma (10%-0.1 ml) or leukotriene B4 (1 microM/0.1 ml) and migrated after the application of a local irritant stimulus (carrageenan, 100 microg/0.1 ml). Leukocyte counts, erythrocyte velocity and venular shear rate, unaltered in diabetic rats, were not modified by this treatment. Reactive oxygen species formation by endothelial cells increased in diabetic preparations, and the reduced expression of adhesion molecules such as intercellular adhesion molecule-1 (ICAM-1) and P-selectin in cross-sections of the whole testis of the animals, were both restored by the antioxidant agent. Therefore, antioxidant treatment improves leukocyte-endothelial interaction in diabetic rats at least in part by restoring the expression of adhesion molecules in venules of diabetic rats.

Antioxidant activity in medicinal plants associated with the symptoms of diabetes mellitus used by the indigenous peoples of the North American boreal forest

Thirty-five plant species were selected from the published literature as traditionally used by the Indigenous Peoples of the boreal forest in Canada for three or more symptoms of diabetes or its complications. Antioxidant activities in methanolic extracts support the contribution of these traditional medicines in a lifestyle historically low in the incidence of diabetes. In a DPPH assay of free radical scavenging activity 89% of the methanol extracts had activity significantly greater than common modern dietary components, 14% were statistically equal to ascorbic acid and 23% had activities similar to green tea and a Trolox positive control. Superoxides produced with an NBT/xanthine oxidase assay found scavenging was significantly higher in 29% of the species as compared with the modern dietary components and Trolox. The methanol extracts of Rhus hirta, Quercus alba and Cornus stolonifera performed similarly to green tea's in this assay. Assessment of peroxyl radical scavenging using a DCF/AAPH assay showed 60% of the plant extracts statistically similar to Trolox while R. hirta and Solidago canadensis extracts were greater than green tea, ascorbic acid and Trolox. The majority of the species (63 and 97%, respectively) had scavenging activities similar to ascorbic acid in the superoxide and peroxyl radical scavenging assays.

Antioxidant therapy potentiates antihypertensive action of insulin in diabetic rats

BACKGROUND

Poorly controlled longstanding diabetes frequently results in sustained hypertension (HTN) which plays a major role in the pathogenesis of diabetic nephropathy. In addition, hyperglycemia, per se, causes a reversible rise in blood pressure (BP) and increases production of reactive oxygen species (ROS). Increased ROS activity may raise BP by promoting inactivation of nitric oxide (NO) and/or nonenzymatic generation of vasoconstrictive prostaglandins from peroxidation of arachidonic acid. Therefore, we hypothesized that antioxidant therapy may enhance the BP-lowering effect of glycemia control with insulin replacement in diabetes.

METHODS

Male Sprague-Dawley rats were rendered diabetic by streptozotocin administration and randomized to untreated, antioxidant-treated (vitamin E-fortified food, tocopherol 5000 U/kg chow and vitamin C-fortified H2O, 1000 mg/L), insulin-treated and insulin plus antioxidant-treated groups. Normal rats fed a regular diet or antioxidant-fortified diet served as controls and monitored for 4 weeks.

RESULTS

The diabetic animals showed marked hyperglycemia, HTN, proteinuria, depressed tissue glutathione level and elevated plasma lipid peroxidation product, malondialdehyde (MDA) denoting increased ROS activity. Insulin therapy alone resulted in significant, but incomplete reduction in BP and plasma MDA but not proteinuria. Antioxidant therapy alone had no effect on the measured parameters in either the diabetic or control animals. However, combined insulin and antioxidant therapies normalized BP, plasma MDA and urinary protein in the diabetic animals. As expected, uncontrolled diabetes resulted in glomerular hyperfiltration which was partially reversed by insulin therapy, but was unaffected by antioxidant therapy.

CONCLUSION

Uncontrolled hyperglycemia in the early phase of diabetes was associated with elevated plasma MDA, HTN and proteinuria. Insulin therapy alone resulted in significant but incomplete reduction of plasma MDA and BP. Antioxidant therapy which was ineffective when given alone, normalized plasma MDA, BP and reduced urinary protein excretion when combined with insulin treatment.

Selenium-deficient diet induces renal oxidative stress and injury via TGF-beta1 in normal and diabetic rats

BACKGROUND

Oxidative stress has been implicated in the pathogenesis of diabetic nephropathy. Although glucose itself can initiate oxidative stress, deficiency of essential trace elements such as selenium (Se) may exacerbate this oxidative stress in diabetic rats. The mechanism by which Se deficiency causes oxidative stress and renal injury is not completely understood. This study tested the hypothesis that Se deficiency induces renal oxidative stress and renal injury via transforming growth factor-beta1 (TGF-beta1).

METHODS

Fifty-four male Wistar rats were used. Diabetes was induced in 27 rats by streptozotocin, and the other 27 rats received buffer only. Ten weeks after induction of diabetes, both normal and diabetic rats were killed, their kidneys removed, and glomeruli were isolated. Glomeruli from normal and diabetic rats were incubated in the presence of TGF-beta1 alone or its neutralizing antibody. Antioxidant enzyme (Cu-Zn) superoxide dismutase (Cu-Zn SOD), catalase, and glutathione peroxidase (GSH-Px) activities; total glutathione; and lipid peroxidation were determined. For Se studies, 15 normal and 15 diabetic rats were divided into groups of five each and fed either a regular, Se-deficient, or Se-supplemented diet one week after induction of diabetes. Ten weeks after feeding these diets, rats were killed and glomeruli were isolated. Oxidative stress was examined by determining the mRNA expressions for antioxidant enzymes and also for TGF-beta1. Plasma glucose and albuminuria were determined. Histology of the kidney and interlobular artery was evaluated by light microscopy.

RESULTS

In vitro studies showed that TGF-beta1 significantly reduced glomerular catalase and GSH-Px activities as well as total glutathione levels with an increase in lipid peroxidation in both normal and diabetic rats. Antibody to TGF-beta abrogated these changes. There was no effect of TGF-beta1 on Cu-Zn SOD. Like TGF-beta1, a Se-deficient diet caused a significant decrease in glomerular mRNA expression for Cu-Zn SOD, catalase, and GSH-Px, but a significant increase in TGF-beta1 mRNA expression. Also, a Se-deficient diet caused an increase in albuminuria, glomerular sclerosis, and plasma glucose levels in both normal and diabetic rats. The deficient diet caused a decrease in the lumen size of the interlobular artery. Se supplementation to diabetic rats up-regulated mRNA expression for antioxidant enzymes, and significantly reduced but did not normalize that of TGF-beta1. Glomerular sclerosis was normalized and the interlobular artery lumen size was greatly enlarged in diabetic rats by Se supplementation. Also, the tubulointerstitium was preserved by Se supplementation in diabetic rats.

CONCLUSIONS

The data show that TGF-beta1 is a pro-oxidant and Se deficiency increases oxidative stress via this growth factor. In addition, Se deficiency may simulate hyperglycemic conditions. Se supplementation to diabetic rats prevents not only oxidative stress but renal structural injury, as well.

Insulinomimetic bis(maltolato)zinc(II) complex: blood glucose normalizing effect in KK-A(y) mice with type 2 diabetes mellitus

High blood glucose levels of KK-A(y) mice with type 2 diabetes mellitus were normalized by daily intraperitoneal (ip) administration of a zinc(II) complex, bis(maltolato)zinc(II) (Zn(Mal)(2)) with a Zn(O(4)) coordination mode, following the finding of strong in vitro insulinomimetic activity in isolated rat adipocytes treated with epinephrine in terms of the inhibition of free fatty acid release. The blood glucose level was maintained in the normal range during administration of the Zn(Mal)(2) complex for 14 days and improvements in the glucose tolerance were confirmed by an oral glucose tolerance test.

Levels of peripheral blood cell DNA damage in insulin dependent diabetes mellitus human subjects

Increased production of reactive oxygen species (ROS) in vivo can lead to cellular biomolecule damage. Such damage has been suggested to contribute to the pathogenesis of insulin dependent diabetes mellitus (IDDM). In this study, we used the alkaline comet assay to measure DNA damage (single-stranded DNA breaks and alkali-labile sites) in freshly isolated whole blood, lymphocytes, monocytes, and neutrophils from 23 subjects with IDDM and 32 age- and sex-matched controls. Analysis of the results showed elevated levels of DNA damage (expressed as % comet tail DNA) in the lymphocyte (4.10+/-0. 47, 3.22+/-0.22), monocyte (4.28+/-0.47, 3.49+/-0.18), and whole blood (4.93+/-0.51, 4.51+/-0.23) fractions from IDDM subjects compared to controls, respectively, but the increases observed were not statistically significant. However, we found significantly elevated basal levels of DNA damage in the neutrophil fraction (8. 38+/-0.64, 4.07+/-0.23; p<0.001, Mann-Whitney U test) in IDDM subjects compared to controls. Given these novel neutrophil findings, we extended the study to include a total of 50 IDDM subjects and 50 age- and sex-matched control subjects and determined basal levels of DNA damage in the neutrophils of all 100 subjects. We found significantly elevated mean levels of DNA damage (8.40+/-0.83, 4. 34+/-0.27; p<0.001, Mann-Whitney U test) in the neutrophils from the IDDM subjects when compared to controls. Our results show that even with acceptable glycaemic control there is a significantly elevated level of DNA damage within diabetic neutrophils in vivo.

2,4-dinitrophenylhydrazine carbonyl assay in metal-catalysed protein glycoxidation

Using an experimental in vitro glycation model, long-term incubations of bovine serum albumin with glucose (fructose) resulted in a significant increase in protein content of 2,4-dinitrophenylhydrazine (DNPH)-reactive carbonyl groups, which could be strongly inhibited by anaerobiosis and metal chelation. The pattern of yields of the protein-bound DNPH was not in accordance with that of the sugar-derived carbonyls determined as the ketoamine Amadori product. In spite of the fact that the contribution of the final advanced glycation end-products to the total DNPH-reactivity of glycation-altered protein remains unclear, the present results stress the need of oxidative steps in formation of most of the DNPH-reactive carbonyl compounds generated by glycation. The results provide evidence that, in protein glycoxidation, the DNPH assay is selective enough to discriminate between protein-bound carbonyls produced by metal-catalysed oxidations and those formed in the early glycation steps.

Protection from glutathione depletion by a glyconutritional mixture of saccharides

A complex glyconutritional (GN) mixture of mono-, di-and polysaccharides was investigated to assess its capacity to protect two different types of rodent cells, rat hepatocytes and mouse splenocytes, from depletion of glutathione by a sulfhydryl-reactive mycotoxin, patulin, or by coxsackievirus B3 (CVB3) infection, respectively. Rat hepatocytes were treated with the GN mixture in vitro or received carrier medium only prior to treatment with patulin. When treated with the GN mixture prior to patulin exposure hepatocytes demonstrated protection against depletion of intracellular reduced glutathione (GSH). Cells treated with the GN for up to 15 hours prior to patulin exposure showed no increase in protection of GSH above that demonstrated by cells treated for 3 hours. Mice were infected with CVB3 and one treatment group was injected intraperitoneally with the GN once a week. Animals were splenectomized each month over a ten month treatment for analysis of spleen monocytic cells. Splenocytes from mice treated with the GN mixture did not show the virally-associated depletion of intracellular GSH or damage to pancreatic acini observed in CVB3 inoculated but non-GN-treated mice. Animals from which spleen cells were taken for analysis showed no decrease in anti-CVB3 antibodies and no decrease in viral titers to accompany or explain the normal levels of intracellular GSH. These data strongly suggest that a complex mixture of exogenous saccharides exerts a protective effect on liver cells in vitro in that the cells are protected from chemically initiated depletion of intracellular GSH, and on spleen cells in vivo in that the cells are protected against a CVB3-initiated decrease in intracellular GSH and increase in pancreatic acini damage.

Nerve function and oxidative stress in diabetic and vitamin E-deficient rats

Nerve dysfunction in diabetes is associated with increased oxidative stress. Vitamin E depletion also leads to enhanced presence of reactive oxygen species (ROS). We compared systemic and endoneurial ROS activity and nerve conduction in vitamin E-depleted control and streptozotocin-diabetic rats (CE- and DE-), and in normally fed control and diabetic animals (CE+ and DE+). Nerve conduction was reduced in both diabetic groups. Vitamin E depletion caused a small further nerve conduction deficit in the diabetic, but not in the control animals. The combination of vitamin E deficiency and streptozotocin-diabetes (group DE-) appeared to be lethal. In the remaining groups, an important rise in sciatic nerve malondialdehyde (MDA) was observed in the vitamin E-depleted control rats. In contrast, plasma MDA levels were elevated in group DE+ only, whereas hydrogen peroxide levels were increased in group CE-. Endoneurial total and oxidized glutathione and catalase were predominantly elevated in group DE+. These data show that nerve lipid peroxidation induced by vitamin E depletion does not lead to reduced nerve conduction or changes in antioxidant concentrations as observed in STZ-diabetes. The marked systemic changes in MDA and antioxidants suggest that nerve dysfunction in experimental hyperglycemia is rather a consequence of systemic than direct nerve damage.

Superoxide dismutase activity in lymphocytes and polymorphonuclear cells of diabetic patients

Copper-zinc superoxide dismutase (Cu,Zn-superoxide dismutase) activity was evaluated in lymphocytes and polymorphonuclear cells of insulin-dependent (n = 33) and non-insulin-dependent (n = 34) diabetic patients. A commercial method for the measurement of superoxide dismutase activity was adapted for use on a discrete analyser and evaluated for interference by other antioxidants with superoxide anion-scavenging properties. In comparison to healthy control subjects (n = 32), a significantly lower Cu,Zn-superoxide dismutase activity was found in both lymphocytes and polymorphonuclear cells of insulin-dependent (2.08 +/- 0.58 vs. 1.70 +/- 0.46 U/mg protein, p < 0.05, and 1.06 +/- 0.46 vs. 0.64 +/- 0.40 U/mg protein, p < 0.001, respectively) and non-insulin-dependent diabetic patients (2.08 +/- 0.58 vs. 1.61 +/- 0.48 U/mg protein, p < 0.01, and 1.06 +/- 0.46 vs. 0.53 +/- 0.24 U/mg protein, p < 0.001, respectively). There was a week, but significant negative correlation between age and Cu,Zn-superoxide dismutase activity in lymphocytes and polymorphonuclear cells (r = -0.22 and r = -0.28, p < 0.05, respectively), whereas no influence of gender, diabetes duration and glycaemic control was observed. The results indicate that diabetes mellitus could elicit a significant disturbance in superoxide anion-scavenging potential of lymphocytes and polymorphonuclear cells.

Renal cortical expression of mRNAs for antioxidant enzymes in normal and diabetic rats

Increased oxidative stress has been implicated in the development of vascular complications of diabetes. In this study, we examined the hypothesis whether chronic hyperglycemia induces oxidative stress by lowering renal expression and activity of antioxidant enzymes and a decrease in glutathione, an antioxidant, in streptozotocin diabetic rats. The results show that the expression of mRNAs for Cu/Zn superoxide dismutase and glutathione peroxidase was significantly increased and that of catalase was decreased in diabetic rats. However, the superoxide dismutase activity was significantly lower in diabetic than normal glomeruli, whereas the activities of the other two enzymes correlated with their mRNA expression. Total glutathione content was significantly decreased in diabetic compared to normal glomeruli. The data suggest that hyperglycemia induces oxidative stress by overexpressing rather than lowering certain antioxidant enzyme mRNAs in the kidney of diabetic rats. Enhanced nonenzymatic glycation of enzyme protein seems to be the cause for the observed decrease in glomerular superoxide dismutase activity.