| 1 | Dose-dependent cysteine-mediated protection of insulin-producing
cells from damage by hydrogen peroxide.
Rasilainen S, Nieminen JM, Levonen AL, Otonkoski T, Lapatto R.
Haartman Institute, Transplantation Laboratory, University of Helsinki, Helsinki, Finland Aims/Hypothesis: Oxidative damage is believed to play a key role in the
process of pancreatic beta cell destruction leading to type 1 diabetes.
The beta cells are sensitive to oxidative stress because their
intracellular anti-oxidative defence mechanisms are weak. The defence
mechanisms depend heavily on glutathione, the synthesis of which is
dependent on the availability of cysteine. We investigated whether an
increased amount of cysteine available could protect beta cells from
oxidative damage. Methods: Rat insulinoma cells (RINm5F) were exposed to
50 or 100&mgr;M hydrogen peroxide in the presence of three different
cysteine concentrations (0.1, 1 and 5mM). Cell viability was analyzed by
vital staining and the cellular metabolic status by
C,N-diphenyl-N'-4,5-dimethyl thiazol-2-yl tetrazolium bromide (MTT)
analysis. Intracellular insulin, DNA and glutathione contents were
measured. The mechanism of death was further clarified by gel
electrophoretic DNA fragmentation analysis. Results: Hydrogen peroxide
decreased cell viability and induced functional impairment. Vital staining
indicated that 1mM cysteine effectively protected the cells. The
protective effect was confirmed by the MTT assay showing preserved
metabolic integrity, and by measurements of intact intracellular insulin
and DNA content. Cysteine increased intracellular glutathione. Gel
electrophoretic analysis of DNA revealed hydrogen peroxide-induced
apoptotic fragmentation. This was also abolished by 1mM cysteine. The
therapeutic window of cysteine was narrow: 0.1mM cysteine provided
inadequate protection, and 5mM cysteine was already toxic in this setting.
Conclusion: A proper dose of cysteine could provide a safe and effective
means to protect beta cells from oxidative damage. | |
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| 2 | Administration of beta-carotene suppresses lipid peroxidation in
tissues and improves the glucose tolerance ability of
streptozotocin-induced diabetic rats.
Furusho T, Kataoka E, Yasuhara T, Wada M, Innami S. Department of Nutrition, Junior College of Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-Ku, Tokyo 156-8502, Japan. tfurusho@nodai.ac.jp The present study attempted to examine the antioxidative effect of
dietary beta-carotene (BC) on lipid peroxidation (LPO) in the
streptozotocin (STZ)-induced diabetic rats. Male Sprague-Dawley (SD) rats
were fed on the AIN76 standard diet with or without 0.1% BC. On the 21st
day after introduction of these diets, STZ was intraperitoneally injected
in half the subjects of both groups. All animals were sacrificed seven
days after the STZ injection. Glucose tolerance and thiobarbituric acid
reactive substance (TBARS) in the tissues or serum were measured. Body
weight gain in the BC + STZ group was significantly higher than that in
the STZ group (p < 0.05). Blood glucose and TBARS concentrations of the
liver, pancreas, and serum in the BC + STZ group were significantly lower
than those in the STZ group. The blood insulin concentration in the BC +
STZ group was significantly higher than that in the STZ group. The hepatic
and serum beta-carotene concentrations in the BC + STZ group were
significantly lower than those in the BC group. Moreover, the synthesis
and oxidation of glutathione (GSH) in the BC + STZ group were reduced when
compared to the STZ group. These results suggest that the administration
of beta-carotene suppresses the elevation of LPO and reduces the symptoms
of diabetes mellitus (DM) in the STZ-induced diabetic rats. | |
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| 3 | Evaluation of oxidative stress in diabetic patients after
supplementation with a standardised red orange extract.
Bonina FP, Leotta C, Scalia G, Puglia C, Trombetta D, Tringali G,
Roccazzello AM, Rapisarda P, Saija A. Dipartimento di Scienze Farmaceutiche, Università di Catania, Italy. boninaf@mbox.unict.it Diabetes mellitus is associated with a high oxidative stress level,
resulting from an imbalance between free radicals or reactive oxygen
species production and the antioxidant systems. Inhibition of these
oxidative processes by co-adjuvant therapy could therefore prevent, or at
least delay, the onset and/or the development of long-term diabetic
complications. Dietary supplementation with plant biophenols may be a
successful strategy to decrease this risk of pathological complications.
The Red Orange Complex (ROC) is a standardized red orange extract
containing, as its main active principles, phenolic compounds
(anthocyanins, flavanones and hydroxycinnamic acids) as well as ascorbic
acid. The aim of the present preliminary study was to evaluate the effects
of short-term (2 mo) dietary supplementation with ROC (50 mg/d, orally) on
some serum non-invasive biomarkers of oxidative stress (total antioxidant
status, or TAS, levels of thiol groups and levels of free radicals) in a
group of 33 patients with Type 2 diabetes, in comparison with a group of
28 healthy volunteers. The results obtained demonstrate that in diabetic
patients supplementation with ROC can improve blood levels of thiol groups
on proteins (an indirect measurement of glutathione activity in serum);
furthermore, it can elicit a marked decrease in serum free radical levels,
in patients with high blood oxidative stress status. However, ROC
supplementation appeared unable to modify serum TAS. Finally, the glycemic
profile remained stable during the study period in all subjects, and no
unpleasant side effects were reported. In conclusion, the treatment of
diabetic patients with ROC might be of therapeutic benefit in order to
protect against diabetes complications that are partially due to
uncontrolled lipid oxidation. D | |
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| 4 | Effect of omega-3 fatty acids on lipid peroxidation and antioxidant
enzyme status in type 2 diabetic patients.
Kesavulu MM, Kameswararao B, Apparao Ch, Kumar EG, Harinarayan CV.
Department of Biochemistry, Sri Venkateswara University Tirupati, 517502, India. BACKGROUND: This study was conducted to investigate the effect of
omega-3 fatty acids on lipid peroxidation and antioxidant enzyme
activities in non-insulin dependent diabetic patients. METHODS:
Thirty-four non-insulin dependent diabetic patients were selected for this
study and they were initially treated with antidiabetic drugs alone for
one month. This was followed by supplementation with omega-3 fatty acids
(1,080 mg of EPA and 720 mg of DHA per day) along with the antidiabetic
drugs for a period of two months. RESULTS: No change in glycaemic control
was observed in diabetic patients at the end of two months of omega-3
fatty acids therapy along with antidiabetic drugs. The combined treatment
significantly reduced serum triglycerides (2.07 +/- 0.94 mmol/l, before
combined therapy vs 1.54 +/- 0.49 mmol/l after combined therapy,
P<0.05) and increased HDL-cholesterol levels (0.93 +/- 0.099 mmol/l,
before combined therapy vs 1.04 +/- 0.098 mmol/l after therapy,
P<0.01). The raised lipid peroxide levels (5.14 +/- 0.61 micromol MDA/l
in controls vs 6.36 +/- 1.56 micromol MDA/l in diabetic patients,
P<0.001) were significantly decreased in these patients after the
combined therapy (6.36 +/- 1.56 micromol MDA/l, before combined therapy vs
5.16 +/- 0.7 micromol MDA/l, after combined therapy, P<0.01). Among the
erythrocyte antioxidant enzymes, the Glutathione peroxidase activity was
increased (32.5 +/- 9.9 U/g Hb/min, before combined therapy vs 42.25 +/-
4.6 U/g Hb/min, after combined therapy, P<0.01) while no change was
observed in Catalase (99.7 +/- 30.4 KU/g Hb before combined therapy vs
85.35 +/- 23.41 KU/g Hb, after combined therapy) and Superoxide dismutase
activities (2.6 +/- 1.04 U/mg Hb/min, before therapy vs 3.01 +/- 1.08 U/mg
Hb/min, after combined therapy) after the 2 months of combined treatment
with antidiabetic agents and omega-3 fatty acids. CONCLUSION:
Supplementation with omega-3 fatty acids has beneficial effects on serum
triglycerides, HDL-cholesterol, lipid peroxidation and antioxidant
enzymes, which may lead to decreased rate of occurrence of vascular
complications in diabetes. | |
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| 5 | Changes in endoneurial blood flow, motor nerve conduction velocity
and vascular relaxation of epineurial arterioles of the sciatic nerve in
ZDF-obese diabetic rats.
Coppey LJ, Gellett JS, Davidson EP, Dunlap JA, Yorek MA.
Veterans Affairs Medical Center, Diabetes Endocrinology Research Center and Department of Internal Medicine, University of Iowa, Iowa City, IA 52246, USA. BACKGROUND: We have previously reported that in streptozotocin-induced
diabetic rats, reduction in endoneurial blood flow (EBF) and impairment of
acetylcholine-mediated vascular relaxation of arterioles that provide
circulation to the sciatic nerve precedes slowing of motor nerve
conduction velocity (MNCV). However, in animal models of type 2 diabetes
it is unknown whether slowing of MNCV is accompanied by vascular
dysfunction. METHODS: Using ZDF-lean and ZDF-obese diabetic rats we
examined whether diabetes-induced slowing in MNCV was associated with a
reduction in EBF and impaired vascular relaxation in epineurial arterioles
of the sciatic nerve. We measured MNCV in the sciatic nerve using a
non-invasive procedure, and sciatic nerve nutritive blood flow using
microelectrode polarography. In vitro videomicroscopy was employed to
quantify arteriolar diameter responses to acetylcholine in arterioles
overlying the sciatic nerve. RESULTS: MNCV and EBF in hyperglycemic
(4-week duration) ZDF-obese diabetic rats were significantly decreased by
30% and 63%, respectively, compared to age-matched ZDF-lean rats.
Acetylcholine elicited a dose-dependent dilation of epineurial vessels
from ZDF-lean and ZDF-obese diabetic rats, although acetylcholine-induced
dilation was significantly reduced in ZDF-obese diabetic rats.
Determination of markers of oxidative stress provided ambiguous results.
Superoxide levels were increased in epineurial vessels from ZDF-obese
diabetic rats. Lens glutathione levels were decreased and serum
thiobarbituric acid reactive substances increased in ZDF-obese diabetic
rats but sciatic nerve conjugated diene and glutathione levels were not
significantly different compared to ZDF-lean rats. CONCLUSIONS: Diabetes
causes a reduction in EBF and impairment in vascular relaxation in
epineurial vessels in ZDF-obese diabetic rats. This impaired vascular
response is associated with neural dysfunction. | |
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| 6 | Xanthine oxidase is involved in free radical production in type 1
diabetes: protection by allopurinol.
Desco MC, Asensi M, Marquez R, Martinez-Valls J, Vento M, Pallardo FV,
Sastre J, Vina J. Department of Physiology, Faculty of Medicine, University of Valencia, Valencia, Spain. Department of Endocrinology, University Clinic, Valencia, Spain. The aim of this work was to study the mechanism of free radical
formation in type 1 diabetes and its possible prevention. We have found
oxidation of blood glutathione and an increase in plasma lipoperoxide
levels in both human type 1 diabetes and experimental diabetes. Peroxide
production by mitochondria does not increase in diabetes. On the contrary,
the activity of xanthine oxidase, a superoxide-generating enzyme,
increases in liver and plasma of diabetic animals. The increase in plasma
xanthine oxidase activity may be explained by the increase in the hepatic
release of this enzyme, which is not due to nonspecific membrane damage:
release of other hepatic enzymes, such as the amino transferases, does not
increase in diabetes. Superoxide formation by aortic rings of rabbits
increases significantly in diabetes. This is completely inhibited by
allopurinol, an inhibitor of xanthine oxidase. Heparin, which releases
xanthine oxidase from the vessel wall, also decreases superoxide formation
by aortic rings of diabetic animals. Treatment with allopurinol decreases
oxidative stress in type 1 diabetic patients: hemoglobin glycation,
glutathione oxidation, and the increase in lipid peroxidation are
prevented. These results may have clinical significance in the prevention
of late-onset vascular complications of diabetes. | |
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| 7 | Thyroid hormone receptor interacting protein 3 (trip3) is a novel
coactivator of hepatocyte nuclear factor-4alpha.
Iwahashi H, Yamagata K, Yoshiuchi I, Terasaki J, Yang Q, Fukui K, Ihara
A, Zhu Q, Asakura T, Cao Y, Imagawa A, Namba M, Hanafusa T, Miyagawa J,
Matsuzawa Y. Department of Internal Medicine and Molecular Science, Graduate School of Medicine, Osaka University, Osaka, Japan. Mutations of the hepatocyte nuclear factor-4alpha (HNF-4alpha) gene are
associated with a subtype of maturity-onset diabetes of the young (MODY1)
that is characterized by impaired insulin secretion in response to a
glucose load. HNF-4alpha, which is a transcription factor expressed in
pancreatic beta-cells, plays an important role in regulating the
expression of genes involved in glucose metabolism. Thus, cofactors that
interact with HNF-4alpha and modify its transcriptional activity might
also play an important role in regulating the metabolic pathways in
pancreatic beta-cells, and the genes of such cofactors are plausible
candidate genes for MODY. In the present study, we showed, using a yeast
two-hybrid screening assay, that thyroid hormone receptor interacting
protein 3 (Trip3) interacted with HNF-4alpha, and their interaction was
confirmed by the glutathione S-transferase pull-down assay. Human Trip3
cDNA contained an open reading frame for a protein of 155 amino acids, and
the gene was expressed in both pancreatic islets and MIN6 cells.
Cotransfection experiments indicated that Trip3 could enhance (two- to
threefold) the transcription activity of HNF-4alpha in COS-7 cells and
MIN6 cells. These results suggest that Trip3 is a coactivator of
HNF-4alpha. Mutation screening revealed that variation of the Trip3 gene
is not a common cause of MODY/early-onset type 2 diabetes in Japanese
individuals. Trip3 may play an important role in glucose metabolism by
regulating the transcription activity of HNF-4alpha. | |
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| 8 | Fetal pig beta cells are resistant to the toxic effects of human
cytokines.
Bai L, Tuch BE, Hering B, Simpson AM. Diabetes Transplant Unit, Prince of Wales Hospital and University of New South of Wales, Sydney, New South Wales, Australia. BACKGROUND: The cytokine tumour necrosis factor-alpha (TNF-alpha) is thought to be responsible for primary nonfunction of islets when transplanted. This, and two other cytokines, interleukin-1beta (IL-1beta) and interferon-gamma (IFN-gamma) are also implicated in the autoimmune destruction of beta cells. It is unknown if the fetal pig beta cell, which is being transplanted as a treatment for type 1 diabetes, is affected by these cytokines. METHODS: We compared the effects of the cytokines on the function and viability of adult and fetal pig beta cells. The cells were cultured for up to 3 days in the presence of 2000 pg/ml of human IL-1beta, 1000 U/ml of TNF-alpha, and 1000 U/ml of IFN-gamma, as well as 1000 U/ml of porcine IFN-gamma. Cumulative insulin levels, insulin content, metabolic activity, and viability of these cells were examined. Additionally, nitric oxide production and the activity of antioxidant enzymes in these cells were also determined. RESULTS: TNF-alpha and the combination of the three human cytokines caused a transient increase in cumulative insulin levels. TNF-alpha alone enhanced insulin content on day 3. There was no effect of these human cytokines on mitochondrial function and viability. In contrast, porcine IFN-gamma inhibited fetal pig beta cell function and also caused their death. Adult pig islets are sensitive to the toxic effects of human TNF-alpha, IL-1beta, the combination of the three cytokines, and porcine IFN-gamma. The activity of the antioxidant enzymes catalase, glutathione peroxidase, and superoxide dismutase were significantly higher in fetal pig beta cells than in adult islets, implying that this may be the reason for the lack of adverse effects of the cytokines on the fetal beta cell. CONCLUSION: Fetal pig beta cells are resistant to the toxic effect of the human cytokines, TNF-alpha and IL-1beta, in vitro. This resistance suggests that fetal, but not adult beta cells, when transplanted into humans with type 1 diabetes may be protected from primary nonfunction and will be partially protected from autoimmune destruction. MeSH Terms:
From PubMed | |
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| 9 | Effect of treating streptozotocin-induced diabetic rats with
sorbinil, myo-inositol or aminoguanidine on endoneurial blood flow, motor
nerve conduction velocity and vascular function of epineurial arterioles
of the sciatic nerve.
Coppey LJ, Gellett JS, Davidson EP, Dunlap JA, Yorek MA. Veterans Affairs Medical Center, Department of Internal Medicine, University of Iowa, Iowa City 52246, USA. Previously we have demonstrated that diabetes causes impairment in vascular function of epineurial vessels, which precedes the slowing of motor nerve conduction velocity. Treatment of diabetic rats with aldose reductase inhibitors, aminoguanidine or myo-inositol supplementation have been shown to improve motor nerve conduction velocity and/or decreased endoneurial blood flow. However, the effect these treatments have on vascular reactivity of epineurial vessels of the sciatic nerve is unknown. In these studies we examined the effect of treating streptozotocin-induced rats with sorbinil, aminoguanidine or myo-inositol on motor nerve conduction velocity, endoneurial blood flow and endothelium-dependent vascular relaxation of arterioles that provide circulation to the region of the sciatic nerve. Treating diabetic rats with sorbinil, aminoguanidine or myo-inositol improved the reduction of endoneurial blood flow and motor nerve conduction velocity. However, only sorbinil treatment significantly improved the diabetes-induced impairment of acetylcholine-mediated vasodilation of epineurial vessels of the sciatic nerve. All three treatments were efficacious in preventing the appropriate metabolic derangements associated with either activation of the polyol pathway or increased nonenzymatic glycation. In addition, sorbinil was shown to prevent the diabetes-induced decrease in lens glutathione level. However, other markers of oxidative stress were not vividly improved by these treatments. These studies suggest that sorbinil treatment may be more effective in preventing neural dysfunction in diabetes than either aminoguanidine or myo-inositol. Grant Support:
From PubMed | |
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| 10 | Sulfur in human nutrition and applications in medicine.
Parcell S. American Institute for Biosocial and Medical Research (AIBMR), Tacoma, WA, USA. steveparcell@attbi.com Because the role of elemental sulfur in human nutrition has not been studied extensively, it is the purpose of this article to emphasize the importance of this element in humans and discuss the therapeutic applications of sulfur compounds in medicine. Sulfur is the sixth most abundant macromineral in breast milk and the third most abundant mineral based on percentage of total body weight. The sulfur-containing amino acids (SAAs) are methionine, cysteine, cystine, homocysteine, homocystine, and taurine. Dietary SAA analysis and protein supplementation may be indicated for vegan athletes, children, or patients with HIV, because of an increased risk for SAA deficiency in these groups. Methylsulfonylmethane (MSM), a volatile component in the sulfur cycle, is another source of sulfur found in the human diet. Increases in serum sulfate may explain some of the therapeutic effects of MSM, DMSO, and glucosamine sulfate. Organic sulfur, as SAAs, can be used to increase synthesis of S-adenosylmethionine (SAMe), glutathione (GSH), taurine, and N-acetylcysteine (NAC). MSM may be effective for the treatment of allergy, pain syndromes, athletic injuries, and bladder disorders. Other sulfur compounds such as SAMe, dimethylsulfoxide (DMSO), taurine, glucosamine or chondroitin sulfate, and reduced glutathione may also have clinical applications in the treatment of a number of conditions such as depression, fibromyalgia, arthritis, interstitial cystitis, athletic injuries, congestive heart failure, diabetes, cancer, and AIDS. Dosages, mechanisms of action, and rationales for use are discussed. The low toxicological profiles of these sulfur compounds, combined with promising therapeutic effects, warrant continued human clinical trails. Publication Types:
From PubMed | |
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| 11 | Regulative potential of glutamine---relation to glutathione
metabolism.
Roth E, Oehler R, Manhart N, Exner R, Wessner B, Strasser E, Spittler
A. Department of Surgery, Research Laboratories, Vienna, Austria Glutamine (GLN) is the most abundant free amino acid (AA) in the human
body. Under GLN-free conditions, which can be obtained when cells are
cultivated in vitro, tissue cells cannot grow. Therefore, when classifying
GLN as a "non-essential" AA, one must consider that in the human body GLN
is synthesized from essential AAs and is continuously delivered from
skeletal muscle to other organs. It is fascinating that a relatively
simple AA like GLN can stimulate a large variety of cellular reactions.
GLN stimulates not only the growth of cells but also the expression of
surface antigens, the formation of cytokines, and the synthesis of heat
shock proteins. Further, a GLN deficiency leads to a cell cycle arrest in
G(0) to G(1) and reduces apoptosis. Interestingly, many of these
biological activities also are associated with the cellular reduced oxygen
potential, which depends mainly on the ratio of reduced to oxidized
glutathione. Experimental animal studies have shown that the
administration of GLN increases tissue concentrations of reduced
glutathione. This review describes the relation of GLN to reduced
glutathione metabolism and discusses the alteration of reduced glutathione
metabolism under a variety of clinical conditions such as reperfusion
injury, myocardial infarction, respiratory insufficiency, cancer,
diabetes, liver disease, and clinical protein catabolism. | |
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| 12 | Plasma F2 isoprostanes: direct evidence of increased free radical
damage during acute hyperglycemia in type 2 diabetes.
Sampson MJ, Gopaul N, Davies IR, Hughes DA, Carrier MJ. Bertram Diabetes Research Unit, Norfolk and Norwich University Hospital National Health Service Trust, Norwich, UK. mike.sampson@norfolk-norwich.thenh.com OBJECTIVES: Acute hyperglycemia in type 2 diabetes increases the
generation of plasma 8-epi-prostaglandin F2 (8-epi-PGF2alpha) isoprostane,
a sensitive direct marker of in vivo free radical oxidative damage to
membrane phospholipids. RESEARCH DESIGN AND METHODS: A total of 21
patients with type 2 diabetes underwent an oral 75-g glucose tolerance
test. Plasma 8-epi-PGF2alpha isoprostane concentrations (by gas
chromatography [GC]/mass spectrometry [MS]), intralymphocyte
reduced-to-oxidized glutathione ratios, and plasma total antioxidant
capacity were measured at baseline and 90 min after glucose loading.
RESULTS: Plasma 8-epi-PGF2alpha isoprostane concentrations rose
significantly (P=0. 010) from 0.241 +/- 0.1 to 0.326 +/- 0.17 ng/l after
90 min. Intracellular oxidative balance and plasma antioxidant capacity
did not change in either group. CONCLUSIONS: Plasma concentrations of
8-epi-PGF2alpha isoprostane increase during acute hyperglycemia in type 2
diabetes, providing direct evidence of free radical-mediated oxidative
damage and demonstrating a pathway for an association between acute rather
than fasting hyperglycemia and macrovascular risk in type 2 diabetes.
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| 13 | Glucose-induced oxidative stress in mesangial cells.
Catherwood MA, Powell LA, Anderson P, McMaster D, Sharpe PC, Trimble
ER. Department of Clinical Biochemistry, Queen's University of Belfast, Royal Group of Hospitals, Belfast, United Kingdom. mark.catherwood@bll.n-i.nhs.uk BACKGROUND: Hyperglycemia is a well-recognized pathogenic factor of
long-term complications in diabetes mellitus. Hyperglycemia not only
generates reactive oxygen species but also attenuates antioxidant
mechanisms creating a state of oxidative stress. METHODS: Porcine
mesangial cells were cultured in high glucose (HG) for ten days to
investigate the effects on the antioxidant defenses of the cell. RESULTS:
Mesangial cells cultured in HG conditions had significantly reduced levels
of glutathione (GSH) compared with those grown in normal glucose (NG). The
reduced GSH levels were accompanied by decreased gene expression of both
subunits of gamma-glutamylcysteine synthetase (gamma-GCS), the
rate-limiting enzyme in de novo synthesis of GSH. Elevated levels of
intracellular malondialdehyde (MDA) were found in cells exposed to HG
conditions. HG also caused elevated mRNA levels of the antioxidant enzymes
CuZn superoxide dismutase (SOD) and MnSOD. These changes were accompanied
by increased mRNA levels of extracellular matrix proteins (ECM),
fibronectin (FN) and collagen IV (CIV). Addition of antioxidants to high
glucose caused a significant reversal of FN and CIV gene expression;
alpha-lipoic acid also up-regulated gamma-GCS gene expression and restored
intracellular GSH and MDA levels. CONCLUSIONS: The results demonstrate the
existence of glucose-induced oxidative stress in mesangial cells as
evidenced by elevated MDA and decreased GSH levels. The decreased levels
of GSH are as a result of decreased mRNA expression of gamma-GCS within
the cell. Antioxidants caused a significant reversal of FN and CIV gene
expression, suggesting an etiological link between oxidative stress and
increased ECM protein synthesis. | |
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| 14 | Effect of Nigella sativa on glucose concentration, lipid
peroxidation, anti-oxidant defence system and liver damage in
experimentally-induced diabetic rabbits.
Meral I, Yener Z, Kahraman T, Mert N. Department of Physiology, Veterinary Medicine, Yuzuncu Yil University, Van, Turkey. imeral@hotmail.com This study was carried out to investigate whether Nigella sativa could decrease the lipid peroxidation, increase the anti-oxidant defence system and also prevent the lipid-peroxidation-induced liver damage in experimentally induced diabetic rabbits. Fifteen New Zealand male rabbits were divided into three experimental groups: control, diabetic and diabetic and N. sativa-treated. The diabetes mellitus (DMI) was induced in the rabbits using 150 mg/kg of 10% alloxan. The diabetic + N. sativa-treated group was given extract of N. sativa seeds orally every day for 2 months after induction of DM. At the end of the 2-month experiment, blood samples were collected to measure malondialdehyde (MDA), glutathione (GSH), ceruloplasmin and glucose concentration, and livers were harvested for histopathological analysis. Treatment with N. sativa decreased the elevated glucose and MDA concentrations, increased the lowered GSH and ceruloplasmin concentrations, and prevented lipid-peroxidation-induced liver damage in diabetic rabbits. It was concluded that N. sativa might be used in diabetic patients to prevent lipid peroxidation, increase anti-oxidant defence system activity and also prevent liver damage. MeSH Terms:
From PubMed | |
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| 15 | Diabetes impairs the enzymatic disposal of 4-hydroxynonenal in rat
liver.
Traverso N, Menini S, Odetti P, Pronzato MA, Cottalasso D, Marinari UM.
Department of Experimental Medicine (Section of General Pathology), University of Genova, Genova, Italy This study assesses whether the HNE accumulation we formerly observed
in liver microsomes and mitochondria of BB/Wor diabetic rats depends on an
increased rate of lipoperoxidation or on impairment of enzymatic removal.
There are three main HNE metabolizing enzymes: glutathione-S-transferase
(GST), aldehyde dehydrogenase (ALDH), and alcohol dehydrogenase (ADH). In
this study we show that GST and ALDH activities are reduced in liver
microsomes and mitochondria of diabetic rats; in contrast, ADH activity
remains unchanged. The role of each enzyme in HNE removal was evaluated by
using enzymatic inhibitors. The roles of both GST and ALDH were markedly
reduced in diabetic rats, while ADH-mediated consumption was significantly
increased. However, the higher level of lipohydroperoxides in diabetic
liver indicated more marked lipoperoxidation. We therefore think that HNE
accumulation in diabetic liver may depend on both mechanisms: increased
lipoperoxidation and decreased enzymatic removal. We suggest that
glycoxidation and/or hyperglycemic pseudohypoxia may be involved in the
enzymatic impairment observed. Moreover, since HNE exerts toxic effects on
enzymes, HNE accumulation, deficiency of HNE removal, and production of
reactive oxygen species can generate vicious circles able to amplify the
damage. | |
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| 16 | Glibenclamide vs gliclazide in reducing oxidative stress in
patients of noninsulin dependent diabetes mellitus--a double blind
randomized study.
Chugh SN, Dhawan R, Kishore K, Sharma A, Chugh K. Department of Medicine, Pt. BD Sharma PGIMS, Rohtak, Haryana. OBJECTIVE: Parameters of oxidative stress were quantitated in 50 patients with type 2 diabetes mellitus in uncontrolled state and after control using oral glibenclamide or gliclazide. The estimates were further compared between the two groups irrespective of drug used to evaluate the difference, if any. METHODS: The study was a double blind, uncontrolled, noncrossover and randomized trial. Fifty patients of uncontrolled type 2 diabetes were divided in to two groups. Group I (25 patients) received capsule A (glibenclamide) while Group II (25 patients) received capsule B (gliclazide). The parameters studied were Superoxide dismutase (SOD), malonyl-dialdehyde (MDA) and reduced glutathione (GSH). They were done at (a) uncontrolled stage (FBS--165 +/- 16.7 mg/dl, PP--240 +/- 30.1 mg/dl and HbA1--10.5 +/- 0.9% in group I and FBS--150 +/- 15.8 mg/dl, PP--246 +/- 29.1 mg/dl HbA1 10.6 +/- 0.8% in group II) and during controlled stage at 12 weeks (FBS--120 +/- 18.5 mg/dl, PP--180 +/- 19.1 mg/dl and HbA1--8.4 +/- 0.29% in group I and FBS--118 +/- 17.6 mg/dl, PP--176 +/- 20.1 mg/dl and HbA1--8.5 +/- 0.39% in group II patients). RESULTS: The significantly raised levels of MDA and SOD, and decreased levels of reduced glutathione (GSH) during uncontrolled stage of diabetes indicated free radical stress induced lipid peroxidation. The significant fall of MDA and SOD and increased levels of GSH in blood in both groups after control revealed beneficial effects of glycemic control on oxidative stress. The levels were not normalized and stayed higher than those in controls. On intergroup comparison; the control of diabetes with gliclazide (group II) showed improvement in oxidative stress (MDA, GSH) better (p < 0.001) than glibenclamide (group I). CONCLUSION: Oxidative stress in uncontrolled diabetes is decreased with glycemic control. The control of diabetes with gliclazide reduced oxidative stress more than glibenclamide, indicating higher antioxidant properties of gliclazide. Normalization of oxidative stress was not achieved. Further studies are required to see long-term effect of drug therapy in combating oxidative stress after achieving acceptable control of diabetes. Publication Types:
From PubMed | |
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| 17 | The effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on
oxidative enzymes in adipocytes and liver.
Kern PA, Fishman RB, Song W, Brown AD, Fonseca V.
The Central Arkansas Veterans Healthcare System, and The Department of Medicine, Division of Endocrinology, University of Arkansas for Medical Sciences, 598/151 LR, 4300 West 7th Street, Little Rock, AR 72205, USA. kernphilipa@uams.edu Reactive oxygen species are produced in response to environmental toxins, and previous studies have suggested that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) damages a number of target organs through the generation of oxygen free radicals and oxidative stress. Upon exposure, TCDD becomes concentrated in adipose tissue, and adversely affects many organs, including liver. This study examined whether oxidative stress was induced in adipocytes and liver that were exposed to TCDD. 3T3-F442A adipocyte cultures were treated with TCDD (5-200 nM) for up to 72 h, and the activity and mRNA levels of superoxide dismutase (SOD), catalase, and glutathione peroxidase (GSH-Px) in adipocyte cell lysates were measured. The addition of 50 nM TCDD induced a two-fold increase in SOD activity after 48 h (P<0.05). In contrast, TCDD had no significant effect on the activity of catalase or GSH-Px in the adipocytes, and the increase in SOD activity was not accompanied by a change in SOD mRNA levels. To assess the effects of TCDD on oxidative stress enzymes in vivo, male Sprague-Dawley rats were injected weekly for 8 weeks with 30 ng/kg TCDD. In addition, the rats were fed either a low-fat complex-carbohydrate (LFCC) diet, or a high fat sucrose diet (HFS). The HFS diet has previously been shown to induce mild obesity and insulin resistance, without inducing diabetes. SOD, catalase, and GSH-Px activities were measured in the liver and adipose tissue of these rats. TCDD injection resulted in a 52% decrease in catalase activity in the adipose tissue of HFS rats (P<0.05). In contrast, SOD and GSH-Px activities were not altered in adipose tissue of TCDD-injected rats. In liver, however, there were significant decreases in GSH-Px activity in response to TCDD. This effect of TCDD was observed in both the LFCC and HFS dietary groups. In addition, GSH-Px activity in the HFS rats was significantly decreased when compared to GSH-Px activity in LFCC rats, in both TCDD-treated and control groups, suggesting that TCDD and a high fat diet may combine to exacerbate oxidative stress. Thus, TCDD induces complex changes in enzymes of oxidative stress in both adipocytes and liver. In adipocytes, these changes occurred post-transcriptionally, as there were no changes in mRNA levels. In addition, a high fat diet per se also resulted in a decrease in GSH-Px activity in liver. MeSH Terms:
From PubMed | |
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| 18 | Modulation of carbon tetrachloride-induced oxidative stress by
dietary fat in rats(open star).
MacDonald-Wicks LK, Garg ML. Discipline of Nutrition and Dietetics, Faculty of Medicine and Health Sciences, University of Newcastle, 2308, NSW, Australia Oxidative stress is believed to be involved in the pathophysiology of a
number of chronic diseases including atherosclerosis, diabetes, and
cataracts and to accelerate the aging process. The aim of this study was
to elucidate the role of various dietary fats in the in vivo modulation of
CCl(4) induced oxidative stress using rat as a model. Rats were raised on
diets enriched with saturated (Beef Tallow), n-9 (Sunola oil), n-6
(Safflower oil) or n-3 (Flaxseed oil) fatty acids and exposed to elevated
oxidative stress by administration of CCl(4.) Plasma concentration of
8-iso-PGF(2alpha), antioxidant micronutrients and antioxidant enzymes were
measured to examine changes to oxidative stress subsequent to the
administration of CCl(4). The fatty acid profiles of plasma and RBC
membranes reflected the fats fed in the different diets. CCl(4)
administration had no significant effect on fatty acid composition of
plasma or RBC lipids. Plasma 8-iso-PGF(2alpha) concentrations were
elevated by CCl(4) administration regardless of the dietary fat fed.
Within the induced oxidative groups the 8-iso-PGF(2alpha) concentrations
were highest in Safflower oil followed by Sunola oil, Tallow and finally
Flaxseed oil. Induction of oxidative stress by CCl(4) administration was
associated with a significant reduction in Vitamin A content reaching a
significantly lower concentration (P <0.05) in the Tallow and Flaxseed
oil groups. Vitamin E concentrations were significantly lower (p = 0.01)
in the Safflower oil and the Flaxseed oil than in the Tallow diet group
following CCl(4) administration. Superoxide Dismutase (SOD) and
Glutathione Peroxidase (GSHPx) activities were not affected by dietary fat
manipulation. The results of this study indicate that dietary fat can
modulate lipid peroxidation and antioxidant defenses when exposed to a
pro-oxidant challenge. | |
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| 19 | Structural changes of the erythrocyte as a marker of
non-insulin-dependent diabetes: protective effects of
N-acetylcysteine.
Straface E, Rivabene R, Masella R, Santulli M, Paganelli R, Malorni W.
Department of Ultrastructures, Istituto Superiore di Sanità , Viale Regina Elena, 299, Rome, 00161, Italy. Prooxidant-antioxidant imbalance was considered as a hallmark of
age-associated, non-insulin-dependent diabetes (NIDD). The aim of this ex
vivo study was to investigate possible implications of oxidative stress in
the integrity and function of red blood cells (RBCs) from NIDD patients.
Morphometric and analytical cytology studies were conducted. The results
showed: (i) significant alterations of RBC ultrastructure; (ii) relevant
changes of spectrin cytoskeleton; (iii) altered insulin receptor
distribution; and (iv) that treatment with the antioxidizing drug
N-acetylcysteine was capable of significantly counteracting these changes.
These results suggest a reconsideration of RBC integrity as a possible
progression marker in NIDD. MeSH Terms:
From PubMed | |
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| 20 | Alloxan induced cataract in a rat.
Balog Z, Klepac R, Rosic S, Jukic-Lesina T. Department of Ophtalmology, Clinical Hospital Osijek, Osijek, Croatia. We have measured lipid peroxidation and the activity of antioxidant enzymes in lenses of alloxan injected rats. After 12 weeks alloxan treated rats developed lens cataract. Diabetes rats had both lower lens weight and lower level of proteins in soluble fraction of lens homogenate. Alloxan treatment is associated with a significant increase of thiobarbituric acid reactive substances and the activity of antioxidant enzymes superoxide dismutase and catalase. However, diabetes decreased the activity of glutathione peroxidase in rat lenses. These results show that alloxan, which changes antioxidant status in rat lenses, may cause complications associated with diabetes. MeSH Terms:
From PubMed | |
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| 21 | Intracellular glutathione deficiency is associated with enhanced
nuclear factor-kappaB activation in older non-insulin dependent diabetic
patients.
Arnalich F, Hernanz A, Lopez-Maderuelo D, De la Fuente M, Arnalich FM,
Andres-Mateos E, Fernandez-Capitan C, Montiel C. Department of Medicine, Hospital La Paz, School of Medicine, Autonomous University of Madrid, Spain. francisco.arnalich@uam.es Diabetes mellitus may be associated with intracellular glutathione
(GSH) deficiency. Since in vivo studies have shown that plasma
intracellular GSH plays a key role in regulating the activation of nuclear
factor kappaB (NF-kappaB), we have investigated the relationship between
intracellular thiols (GSH, homocysteine, cysteine and cysteinyglycine) and
NF-kappaB activity in the peripheral blood mononuclear cells (PBMC) of 63
elderly non-insulin dependent diabetes mellitus (NIDDM) patients (28
microalbuminurics and 35 normoalbuminurics) and 30 healthy age- and
sex-matched subjects. In addition, we have measured plasma concentrations
of these thiol compounds, serum concentrations of interleukin-6 (IL-6) and
vascular cell adhesion molecule-1 (sVCAM-1), that are partly dependent on
the NF-kappaB activation, as well as the serum levels of thiobarbituric
acid reacting substances (TBARS), as index of lipid peroxidation. Diabetic
patients with microalbuminuria (MAB) and normoalbuminuria had NF-kappaB
activity 2.1- and 1.5-fold greater, respectively, than the control group.
As compared to normoalbuminuric patients, patients with MAB had
significantly higher levels of glycemia, plasma homocysteine, and serum
concentrations of TBARS, IL-6 and sVCAM-1 (in all cases, p < 0.01), and
significantly lower GSH content in the PBMC (p < 0.05). The
intracellular GSH in PBMC correlated with NF-kappaB activation (r = -0.82;
p < 0.0001), serum TBARS (r = -0.60; p < 0.001), and with fasting
glycemia (r = -0.56; p < 0.001) in patients with MAB, whereas a weaker
association between GSH levels in PBMC and NF-kappaB activation (r =
-0.504, p < 0.001) was seen in patients without MAB. These results
suggest that the decrease of intracellular GSH content in elderly NIDDM
patients with MAB is strongly associated with enhanced NF-kappaB
activation, which could contribute to the development of increased
glomerular capillary permeability and its rapid progression. | |
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| 22 | Selenium and glycogen levels in diabetic patients.
Kljai K, Runje R. Medical Faculty, University of Zagreb, Croatia. Selenium in serum and selenium and glycogen in erythrocytes were
determined in diabetic patients divided into noninsulin-dependent (n = 50)
and insulin-dependent (n = 31) groups according to the etiopathogenesis of
their diabetes. Selenium was determined by the method of atomic absorption
spectrometry. Serum level of selenium was statistically significantly
different in patients with either noninsulin-dependent (59.23 +/- 12.2
microg/L) or insulin-dependent (58.23 +/- 16.7 microg/L) diabetes mellitus
as compared with the control group of 62 subjects (64.2 +/- 11.5 microg/L;
p < 0.05). There was no statistically significant difference in the
serum levels of selenium between the groups of patients with
noninsulin-dependent and insulin-dependent diabetes mellitus. The levels
of erythrocyte glycogen were 2.0580 +/- 1.326, 2.0380 +/- 1.735, and
2.0036 +/- 1.3537 microg/g Hb in the control group, noninsulin-dependent
group, and insulin-dependent group, respectively, with no statistically
significant between-group difference. The decreased levels of selenium in
serum and erythrocytes of diabetic patients suggest the possible role of
glutathione peroxidase activity. | |
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| 23 | Characterization of a novel hemoglobin-glutathione adduct that is
elevated in diabetic patients.
Al-Abed Y, VanPatten S, Li H, Lawson JA, FitzGerald GA, Manogue KR,
Bucala R. The Picower Institute for Medical Research, Manhasset, New York 11030, USA. yal-abed@picower.edu BACKGROUND: Typically, a diagnosis of diabetes mellitus is based on
elevated circulating blood glucose levels. In an attempt to discover
additional markers for the disease and predictors of prognosis, we
undertook the characterization of HbA1d3 in diabetic and normal patients.
MATERIAL AND METHODS: PolyCAT A cation exchange chromatography and liquid
chromatography-mass spectroscopy was utilized to separate the alpha- and
beta-globin chains of HbA1d3 and characterize their presence in normal and
diabetic patients. RESULTS: We report the characterization of HbA1d3 as a
glutathionylated, minor hemoglobin subfraction that occurs in higher
levels in diabetic patients (2.26 +/- 0.29%) than in normal individuals
(1.21 +/- 0.14%, p < 0.001). The alpha-chain spectrum displayed a
molecular ion of m/z 15126 Da, which is consistent with the predicted
native mass of the HbA0 alpha-globin chain. By contrast, the mass spectrum
of the beta-chain showed a mass excess of 307 Da (m/z = 16173 Da) versus
that of the native HbA0 beta-globin chain (m/z = 15866 Da). The native
molecular weight of the modified beta-globin chain HbA0 was regenerated by
treatment of HbA1d3 with dithiothreitol, consistent with a
glutathionylated adduct. CONCLUSIONS: We propose that HbA1d3 (HbSSG) forms
normally in vivo, and may provide a useful marker of oxidative stress in
diabetes mellitus and potentially other pathologic situations. | |
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| 24 | Overexpression of metallothionein reduces diabetic
cardiomyopathy.
Liang Q, Carlson EC, Donthi RV, Kralik PM, Shen X, Epstein PN.
Division of Molecular Cardiovascular Biology, University of Cincinnati, Ohio, USA. Many diabetic patients suffer from cardiomyopathy, even in the absence of vascular disease. This diabetic cardiomyopathy predisposes patients to heart failure and mortality from myocardial infarction. Evidence from animal models suggests that reactive oxygen species play an important role in the development of diabetic cardiomyopathy. Our laboratory previously developed a transgenic mouse model with targeted overexpression of the antioxidant protein metallothionein (MT) in the heart. In this study we used MT-transgenic mice to test whether an antioxidant protein can reduce cardiomyopathy in the OVE26 transgenic model of diabetes. OVE26 diabetic mice exhibited cardiomyopathy characterized by significantly altered mRNA expression, clear morphological abnormalities, and reduced contractility under ischemic conditions. Diabetic hearts appeared to be under oxidative stress because they had significantly elevated oxidized glutathione (GSSG). Diabetic mice with elevated cardiac MT (called OVE26MT mice) were obtained by crossing OVE26 transgenic mice with MT transgenic mice. Hyperglycemia in OVE26MT mice was indistinguishable from hyperglycemia in OVE26 mice. Despite this, the MT transgene significantly reduced cardiomyopathy in diabetic mice: OVE26MT hearts showed more normal levels of mRNA and GSSG. Typically, OVE26MT hearts were found to be morphologically normal, and elevated MT improved the impaired ischemic contractility seen in diabetic hearts. These results demonstrate that cardiomyocyte-specific expression of an antioxidant protein reduces damage to the diabetic heart. MeSH Terms:
From PubMed | |
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| 25 | Alpha-lipoic acid attenuates hyperglycemia and prevents glomerular
mesangial matrix expansion in diabetes.
Melhem MF, Craven PA, Liachenko J, DeRubertis FR. Department of Pathology, VA Pittsburgh Healthcare System and University of Pittsburgh, Pittsburgh, Pennsylvania 15240, USA. Previous studies demonstrated that 2 mo of dietary supplementation with alpha-lipoic acid (LA) prevented early glomerular injury in non-insulin-treated streptozotocin diabetic rats (D). The present study examined the effects of chronic LA supplementation (30 mg/kg body wt per d) on nephropathy in D after 7 mo of diabetes. Compared with control rats, D developed increased urinary excretion of albumin and transforming growth factor beta, renal insufficiency, glomerular mesangial matrix expansion, and glomerulosclerosis in association with depletion of glutathione and accumulation of malondialdehyde in renal cortex. LA prevented or ameliorated all of these changes in D. Because chronic LA supplementation also attenuated hyperglycemia in D after 3 mo, its effects on renal injury were compared with treatment of rats with sufficient insulin to maintain a level of glycemic control for the entire 7-mo period (D-INS) equivalent to that observed with LA during the final 4 mo. Despite superior longitudinal glycemic control in D-INS, urinary excretion of albumin and transforming growth factor beta, glomerular mesangial matrix expansion, the extent of glomerulosclerosis, and renal cortical malondialdehyde content were all significantly greater, whereas cortical glutathione content was lower than corresponding values in D given LA. Thus, the renoprotective effects of LA in D were not attributable to improved glycemic control alone but also likely reflected its antioxidant activity. The combined antioxidant and hypoglycemic actions of LA both may contribute to its utility in preventing renal injury and other complications of diabetes. MeSH Terms:
From PubMed | |
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| 26 | Up-regulation of K(+) channels in diabetic rat ventricular myocytes
by insulin and glutathione.
Xu Z, Patel KP, Lou MF, Rozanski GJ. Department of Physiology and Biophysics, University of Nebraska College of Medicine, 984575 Nebraska Medical Center, 68198-4575, Omaha, NE, USA Objective: The cardiac pathogenesis of diabetes mellitus involves
oxidative stress that elicits profound changes in myocardial glutathione,
an endogenous regulator of cell function. This study examined the role of
glutathione in regulating K(+) channel activity in isolated ventricular
myocytes from diabetic rats and its relationship to insulin signaling.
Methods and results: Colorimetric analysis of extracts of ventricular
tissue from Sprague-Dawley rats showed that the basal level of reduced
glutathione (GSH) was significantly less in rats with experimental
diabetes compared with sham controls, consistent with oxidative stress
conditions. This change in GSH status paralleled a significant decrease in
the activity of gamma-glutamylcysteine synthetase, a major pathway
involved in GSH homeostasis. Voltage-clamp studies confirmed that,
compared with control myocytes, K(+) channels carrying the transient
outward current (I(to)) are down-regulated in the diabetic state and that
this electrophysiological change is reversed by in vitro treatment with
insulin for 2-3 h. Incubation of diabetic rat myocytes with GSH also
normalized I(to) density compared with untreated myocytes, but with a
longer time course than insulin. To determine if up-regulation of I(to) by
insulin was mediated by alterations in myocyte GSH, insulin-responsiveness
of diabetic rat myocytes was tested in the presence of
1,3-bis-chloroethyl-nitrosourea, an inhibitor of glutathione reductase, or
buthionine sulfoximine, a blocker of gamma-glutamylcysteine synthetase.
Neither blocker alone altered I(to) density in diabetic rat myocytes when
compared with untreated cells, but each blocked the effect of insulin to
up-regulate I(to). Conclusions: These data suggest that oxidative
stress-induced alteration in GSH redox state plays an important role in
regulating I(to) channel function and that GSH homeostasis in ventricular
myocytes is functionally coupled to insulin signaling. | |
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| 27 | Glyoxalase I deficiency is associated with an unusual level of
advanced glycation end products in a hemodialysis patient.
Miyata T, van Ypersele de Strihou C, Imasawa T, Yoshino A, Ueda Y,
Ogura H, Kominami K, Onogi H, Inagi R, Nangaku M, Kurokawa K.
Molecular and Cellular Nephrology, Institute of Medical Sciences and Department of Medicine, Tokai University School of Medicine, and Bohsei-Hiratsuka Clinic, Kanagawa, Japan. t-miyata@is.icc.u-tokai.ac.jp BACKGROUND: Advanced glycation of proteins and their attendant advanced glycation end products (AGEs) contribute to the complications associated with diabetes mellitus or uremia. Regulatory mechanisms of AGE formation in vivo remain an issue of particular interest. We investigated a role of the glyoxalase detoxification system of precursor reactive carbonyl compounds (RCOs) in the in vivo AGE formation. METHODS: Plasma levels of AGEs [pentosidine and Nepsilon-carboxymethyllysine (CML)], their RCO precursors, d-lactate (the final product resulting from the glyoxalase detoxification pathway), as well as of various compounds known to generate AGE precursors and surrogate markers for oxidative stress (antioxidant enzymes and glutathione), were measured in both hemodialysis (HD) patients and normal subjects. The activity and protein expression of glyoxalase I, an enzyme essential for the detoxification of alpha-oxoaldehydes, in red blood cells (RBC) were also examined. RESULTS: In one 69-year-old lady who had been on hemodialysis (HD) for three years and had suffered from recurrent cardiovascular complications despite the absence of significant risk factors, plasma levels of pentosidine (77.3 +/- 2.4 pmol/mg protein) and CML (330.8 +/- 8.2 pmol/mg protein) were markedly elevated as compared to other HD patients (N = 20: 26.6 +/- 11.8 pmol/mg protein for pentosidine and 224.4 +/- 51.7 pmol/mg protein for CML). The plasma level of RCO precursors for pentosidine and CML was also higher in this patient than in other HD patients. Further investigation disclosed a very low activity in RBC of glyoxalase I (1.5 +/- 0.4 mU/106 RBC), as compared to other HD patients (3.9 +/- 0.6 mU/106 RBC) or normal subjects (4.0 +/- 0.6 mU/106 RBC). The glyoxalase I protein level, assessed in RBC by immunoblot analysis with a specific antibody, was markedly lower than that observed in HD patients and normal subjects. The causes of this deficiency remain unknown. Nucleotide sequencing of the products of reverse transcription-polymerase chain reaction from the patient's mononuclear cells revealed no genetic mutation within the coding region of the glyoxalase I gene. Plasma d-lactate level was also in the lower range (0.18 +/- 0.03 mg/dL) of the values measured in the other HD patients (0.27 +/- 0.09 mg/dL) and normal subjects (0.35 +/- 0.12 mg/dL). The plasma levels of various compounds known to generate AGE precursors (glucose, lipids and ascorbic acid) were either normal or low. The surrogate markers for oxidative stress such as antioxidant enzymes (glutathione peroxidases and superoxide dismutase) and glutathione were all within the range observed in the other HD patients. CONCLUSION: The unusually high levels of AGEs in this patient implicate a deficient glyoxalase detoxification of RCO precursors. The present clinical observation implicates, to our knowledge for the first time, the glyoxalase detoxification system and, in particular, glyoxalase in the actual level of AGEs in a uremic patient. MeSH Terms:
From PubMed | |
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| 28 | Troglitazone selectively inhibits glyoxalase I gene expression.
Wu L, Eftekharpour E, Davies GF, Roesler WJ, Juurlink BH.
Department of Anatomy and Cell Biology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada. AIMS/HYPOTHESIS: The hyperglycaemia associated with diabetes causes excessive production of cytotoxic methylglyoxal, an alpha-oxo-aldehyde. The glyoxalase system, composed of glyoxalase I and glyoxalase II, with glutathione (GSH) as the cofactor, plays an important role in the detoxification of alpha-oxo-aldehydes. We tested the hypothesis that troglitazone, an insulin-sensitizing drug previously used in the treatment of Type II (non-insulin-dependent) diabetes mellitus, up-regulates the glyoxalase system either by increasing phase 2 enzyme activities and thereby increasing cellular GSH, or, by inducing glyoxalase enzyme activities. METHODS: Human astroglial cells, rat hepatocytes and cardiac myocytes were cultured and exposed to either troglitazone, or tertiary-butylhydroquinone (tBHQ, a phase 2 enzyme inducer). Glutathione content, advanced glycation end products (AGEs) and enzyme (glyoxalase I, glyoxalase II as well as the phase 2 enzymes, glutathione S-transferase and thioredoxin reductase) activities were determined. Glyoxalase I mRNA was also measured. RESULTS: Troglitazone had no effect on cellular GSH nor phase 2 enzyme activities but significantly reduced the activities of glyoxalase I and II; this inhibitory effect was concentration-dependent and time-dependent and was associated with reduced mRNA contents and increased AGEs formation. Rosiglitazone had no effect on glyoxalase I gene expression. tBHQ, a classic phase 2 enzyme inducer, had no effect on the glyoxalase system but did increase glutathione contents and the activities of glutathione S-transferase and thioredoxin reductase. CONCLUSION/INTERPRETATION: Our study shows that troglitazone is a selective inhibitor of the glyoxalase system. This inhibition of the glyoxalase system could contribute to troglitazone's hepatotoxic action which has previously been reported in a small percentage of individuals. MeSH Terms:
From PubMed | |
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| 29 | Differences in antioxidant status in skeletal muscle tissue in
experimental diabetes.
Gumieniczek A, Hopkal&z shtsls;a H, Wojtowicz Z, Nieradko M.
Department of Medicinal Chemistry, Medical University of Lublin, Chodzki Str. 6, 20-093, Lublin, Poland Background: It has been suggested that oxidative stress may play an
important role in pathogenesis of diabetic complications. The present
study was designed to evaluate the oxidative stress-related parameters in
alloxan (A)-induced long-term diabetes in rabbits. Methods: After 3, 6 and
12 weeks of diabetes, activities of superoxide dismutase (SOD), catalase
(CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GSSG-R) and
concentrations of ascorbic acid (AA) and free sulfhydryl compounds (SH)
were measured in skeletal muscle of diabetic rabbits and the normal
control subjects. The products of lipid peroxidation (MDA) were also
estimated. Results: In our tests, the muscle SOD activity, SH and AA
concentrations were significantly reduced. CAT activity increased
significantly at all time intervals. GSH-Px activity decreased after 3
weeks and then remained at the control level. GSSG-R activity decreased
progressively at 3rd and 6th week and then significantly increased. MDA
level increased initially, dropped below baseline after 6 weeks and then
remained at the level of the control group. Conclusions: The changes
observed in the present experiment suggest a significant imbalance in
antioxidative system in the skeletal muscle of rabbits with
alloxan-induced diabetes. Such study may lead to therapeutic approaches
for limiting the damage from oxidation reactions and preventing the
diabetic complications. | |
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| 30 | Divergent effects of different oxidants on glutathione homeostasis
and protein damage in erythrocytes from diabetic patients: effects of high
glucose.
Manuel y Keenoy B, Vertommen J, De Leeuw I. Laboratory of Endocrinology, University of Antwerp, Belgium. Long-term complications of diabetes mellitus have been ascribed to both
the effects of prolonged hyperglycemia and to increased oxidative stress.
In an attempt to identify the mechanisms underlying the acute effects of
hyperglycemia on oxidative stress, we investigated the hypothesis that
high glucose might lead to an insufficiency in reducing equivalents (such
as NADPH) and thus to a disruption in the glutathione-dependent
antioxidant defences and to an incapacity to deal with oxidant attack. For
this purpose, erythrocytes from diabetic patients were incubated for 0-90
min in 5.55 or 33.3 mM D-glucose containing tertbutyl hydroperoxide 0.5
and 1 mM, Menadione 100 microM, or glucose oxidase. The time course of the
changes in non-protein bound glutathione (reduced and oxidised), lactate
and pyruvate, alanine and fluorescent products of oxidative proteolysis,
hemolysis and methemoglobin was monitored. The results show that although
glucose utilisation was unaffected, all oxidants caused a persistent
decrease in total non-protein-bound glutathione suggesting binding to
proteins. However, changes in glutathione and redox status differed
between the various oxidants and were not directly related to the extent
of oxidative cellular damage. In these experimental conditions, with short
incubations and using the erythrocyte as the simplest cellular model of
glucose metabolism, neither high glucose nor the diabetic condition
worsened the susceptibility of erythrocytes to acute in vitro oxidative
damage. | |
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| 31 | Susceptibility of insulin-secreting hepatocytes to the toxicity of
pro-inflammatory cytokines.
Tabiin MT, Tuch BE, Bai L, Han XG, Simpson AM. Diabetes Transplant Unit, Prince of Wales Hospital and University of New South Wales, Sydney, Australia. The liver has been suggested as a suitable target organ for reversing
type I diabetes by gene therapy. Whilst gene delivery systems to the
hepatocyte have yet to be optimized in vivo, whether insulin-secreting
hepatocytes are resistant to the autoimmune process that kills pancreatic
beta-cells has never been addressed. One of the mechanisms by which
beta-cells are killed in type I diabetes is by the release of the
cytokines interleukin-1beta (IL-1beta), tumour necrosis factor-alpha
(TNF-alpha) and interferon-gamma (IFN-gamma) by immune cells. To test the
effect of the cytokines on insulin-secreting hepatocytes in vitro we
exposed the betacyte, also called the HEP G2ins/g cell which possesses
cytokine receptors and can synthesize, store and secrete insulin in a
regulated fashion to a glucose stimulus, to the above mentioned cytokines
for 14 days. Viability of the HEP G2ins/g cells was similar to that of
other liver cell lines/primary cells which were more resistant to the
cytokines than the beta-cell line NIT-1. The cytokines had no adverse
effect for the first six days on insulin secretion, content and mRNA
levels of the HEP G2ins/g cells and insulin secretion in response to 1-h
exposure to 20 mM glucose was enhanced 14-fold. Our results indicate that
genetically engineered hepatocytes and primary liver cells are more
resistant than pancreatic beta-cells to the adverse effects of cytokines
offering hope that insulin secreting hepatocytes in vivo made by gene
therapy are less likely to be destroyed by cytokines released during
autoimmune destruction. MeSH Terms:
From PubMed | |
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| 32 | Enalapril attenuates oxidative stress in diabetic rats.
de Cavanagh EM, Inserra F, Toblli J, Stella I, Fraga CG, Ferder L.
Massone Institute, Institute of Cardiovascular Research, Buenos Aires, Argentina. Oxidative stress is involved in both the pathogenesis and complications of diabetes. ACE inhibitors can slow the progression of cardiac and renal impairments related to diabetes. The effect of enalapril treatment on oxidative stress and tissue injury was studied in hearts, kidneys, and livers from streptozotocin-induced diabetic rats. Twenty-four rats were divided into the following groups: streptozotocin (65 mg/kg, single intraperitoneal dose), streptozotocin+enalapril (20 mg enalapril/L drinking water), and control (intraperitoneal saline). Seven months after streptozotocin injection, organs were studied by light microscopy and collagen III immunolabeling. Tissue lesions and collagen labeling were graded by a semiquantitative score (0 to 4). Total glutathione content, glutathione redox status (reduced/oxidized glutathione), antioxidant enzyme activities, protein-associated sulfhydryls, thiobarbituric acid-reactive substances, and fluorescent chromolipids were determined in tissue homogenates. Glycemia was higher in both the streptozotocin and streptozotocin+enalapril groups relative to the control group. In the streptozotocin group, creatinine clearance and body weight were lower, and systolic blood pressure and urinary albumin excretion were higher than in the streptozotocin+enalapril and control groups. Heart, kidney, and liver lesion/labeling scores were significantly higher in the streptozotocin group compared with the streptozotocin+enalapril and control groups. Kidney and liver total glutathione was lower in the streptozotocin group relative to the control group (P<0.05). Enalapril treatment significantly attenuated the reduction of total glutathione. In the heart, kidney, and liver, both glutathione and proteins were relatively more oxidized in the streptozotocin group relative to the control group (P<0.05). Protein and glutathione oxidation were attenuated in the streptozotocin+enalapril group in the 3 tissues studied (P<0.05). Enalapril treatment attenuated the oxidation of lipids in the heart and kidney (P<0.05). Tissue fibrosis scores were inversely correlated with (1) both total glutathione and reduced/oxidized glutathione in heart, kidney, and liver and (2) glutathione reductase activity in the kidney. These results suggest that in streptozotocin-induced diabetic rats, the protective action of enalapril might be mediated, at least in part, by its effect on tissue oxidant/antioxidant status. MeSH Terms:
From PubMed | |
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| 33 | An aldose reductase inhibitor reverses early diabetes-induced
changes in peripheral nerve function, metabolism, and antioxidative
defense.
Obrosova IG, Van Huysen C, Fathallah L, Cao XC, Greene DA, Stevens MJ.
Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0354, USA. iobrosso@umich.edu Aldose reductase inhibitors (ARIs) prevent peripheral nerve dysfunction and morphological abnormalities in diabetic animal models. However, some experimental intervention studies and clinical trials of ARIs on diabetic neuropathy appeared disappointing because of either 1) their inadequate design and, in particular, insufficient correction of the sorbitol pathway activity or 2) the inability to reverse established functional and metabolic deficits of diabetic neuropathy by AR inhibition in general. We evaluated whether diabetes-induced changes in nerve function, metabolism, and antioxidative defense are corrected by the dose of ARI (sorbinil, 65 mg/kg/d in the diet), resulting in complete inhibition of increased sorbitol pathway activity. The groups included control rats and streptozotocin-diabetic rats treated with/without ARI for 2 weeks after 4 weeks of untreated diabetes. ARI treatment corrected diabetes-induced nerve functional changes; that is, decrease in endoneurial nutritive blood flow, motor and sensory nerve conduction velocities, and metabolic abnormalities (i.e., mitochondrial and cytosolic NAD+/NADH redox imbalances and energy deficiency). ARI restored nerve concentrations of two major non-enzymatic antioxidants, reduced glutathione (GSH) and ascorbate, and completely arrested diabetes-induced lipid peroxidation. In conclusion, treatment with adequate doses of ARIs (that is, doses that completely inhibit increased sorbitol pathway activity) is an effective approach for reversal of, at least, early diabetic neuropathy. MeSH Terms:
From PubMed | |
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| 34 | Methylglyoxal enhances cisplatin-induced cytotoxicity by activating
protein kinase Cdelta.
Godbout JP, Pesavento J, Hartman ME, Manson SR, Freund GG. Department of Pathology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA. The cytotoxic side effects of anti-neoplastic drugs are increased in patients with either type 1 or type 2 diabetes mellitus by a mechanism that is not clearly defined. We report that the circulating glucose metabolite, methylglyoxal (MGO), enhances cisplatin-induced apoptosis by activating protein kinase Cdelta (PKCdelta). We found that treatment of myeloma cells with the antioxidant N-acetylcysteine completely blocked cisplatin-dependent intracellular GSH oxidation, reactive oxygen species (ROS) generation, poly(ADP-ribose) polymerase cleavage, and apoptosis. Importantly, co-treatment of cells with the reactive carbonyl MGO and cisplatin increased apoptosis by 90% over the expected additive effect of combined MGO and cisplatin treatment. This same synergism was also observed when ROS generation was examined. MGO and cisplatin increased PKCdelta activity by 4-fold, and this effect was blocked by the PKCdelta inhibitor rottlerin but not by NAC. Furthermore, rottlerin blocked combined MGO and cisplatin-induced ROS generation and apoptosis. Finally, MGO and cisplatin induced c-Abl activation and c-Abl:PKCdelta association. Rottlerin blocked c-Abl activation, but the c-Abl inhibitor STI-571 increased MGO and cisplatin-induced apoptosis by 50%. Taken together these data indicate that MGO synergistically enhances cisplatin-induced apoptosis through activation of PKCdelta and that PKCdelta is critical to both cell death and cell survival pathways. These findings suggest that in the patient with diabetes mellitus heightened oxidative stress can enhance the cytotoxicity of agents that induce DNA damage. MeSH Terms:
From PubMed | |
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| 35 | Increased expression of glutathione S-transferase in renal proximal
tubules in the early stages of diabetes: a study of type-2 diabetes in the
Akita mouse model.
Fujita H, Haseyama T, Kayo T, Nozaki J, Wada Y, Ito S, Koizumi A.
Department of Hygiene, Akita University School of Medicine, Akita, Japan. BACKGROUND/AIM: The objective of this study was to examine whether the
gene expression profile in the kidney is modified by hyperglycemia in the
early stage of diabetes. METHODS: We analyzed the expression of kidney
mRNAs using cDNA array membranes including 588 genes in the kidney of the
Akita mouse, a model of type-2 diabetes, after exposure to hyperglycemia
for a moderate length of time, but before the manifestation of diabetic
glomerulosclerosis. Western blot analysis and immunohistochemical studies
were performed to confirm whether the protein for the increasingly
expressed mRNA was highly expressed in the kidney of the diabetic mouse.
RESULTS: Two of the 10 detected mRNAs, glutathione S-transferase (GST)
alpha and mu, in the kidneys from diabetic mice showed a more than twofold
increased expression in comparison to those of control mice. Western blot
analysis in kidney tissue extracts confirmed increases in GST alpha and mu
at protein levels in the diabetic mice. Immunohistochemical studies
revealed strong staining for those proteins in the proximal tubules of
diabetic mice. CONCLUSION: These data collectively indicate that
expression of GSTs is increased in epithelial cells in proximal tubules
even at the early stage of diabetes, probably in response to oxidative
stress triggered by hyperglycemia or other toxic effects of glucose.
MeSH Terms:
From PubMed | |
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| 36 | Regulation of taurine transporter expression by NO in cultured
human retinal pigment epithelial cells.
Bridges CC, Ola MS, Prasad PD, El-Sherbeny A, Ganapathy V, Smith SB.
Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta, Georgia 30912, USA. Taurine is actively transported at the retinal pigment epithelial (RPE) apical membrane in an Na(+)- and Cl(-)-dependent manner. Diabetes may alter the function of the taurine transporter. Because nitric oxide (NO) is a molecule implicated in the pathogenesis of diabetes, we asked whether NO would alter the activity of the taurine transporter in cultured ARPE-19 cells. The activity of the transporter was stimulated in the presence of the NO donor 3-morpholinosydnonimine. The stimulatory effects of 3-morpholinosydnonimine were not observed during the initial 16-h treatment; however, stimulation of taurine uptake was elevated dramatically above control values with 20- and 24-h treatments. Kinetic analysis revealed that the stimulation was associated with an increase in the maximal velocity of the transporter with no significant change in the substrate affinity. The NO-induced increase in taurine uptake was inhibited by actinomycin D and cycloheximide. RT-PCR analysis and nuclear run-on assays provided evidence for upregulation of the transporter gene. This study provides the first evidence of an increase in taurine transporter gene expression in human RPE cells cultured under conditions of elevated levels of NO. MeSH Terms:
From PubMed | |
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| 37 | Molecular aspects of lipoic acid in the prevention of diabetes
complications.
Packer L, Kraemer K, Rimbach G. Department of Molecular Pharmacology and Toxicology, School of Pharmacy, University of Southern California, 1985 Zonal Avenue, Los Angeles, CA 90098-9121, USA. packerresearch@aol.com Alpha-lipoic acid (LA) and its reduced form, dihydrolipoic acid, are powerful antioxidants. LA scavenges hydroxyl radicals, hypochlorous acid, peroxynitrite, and singlet oxygen. Dihydrolipoic acid also scavenges superoxide and peroxyl radicals and can regenerate thioredoxin, vitamin C, and glutathione, which in turn can recycle vitamin E. There are several possible sources of oxidative stress in diabetes including glycation reactions, decompartmentalization of transition metals, and a shift in the reduced-oxygen status of the diabetic cells. Diabetics have increased levels of lipid hydroperoxides, DNA adducts, and protein carbonyls. Available data strongly suggest that LA, because of its antioxidant properties, is particularly suited to the prevention and/or treatment of diabetic complications that arise from an overproduction of reactive oxygen and nitrogen species. In addition to its antioxidant properties, LA increases glucose uptake through recruitment of the glucose transporter-4 to plasma membranes, a mechanism that is shared with insulin-stimulated glucose uptake. Further, recent trials have demonstrated that LA improves glucose disposal in patients with type II diabetes. In experimental and clinical studies, LA markedly reduced the symptoms of diabetic pathologies, including cataract formation, vascular damage, and polyneuropathy. To develop a better understanding of the preventative and therapeutic potentials of LA, much of the current interest is focused on elucidating its molecular mechanisms in redox dependent gene expression. Publication Types:
From PubMed | |
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| 38 | Taurine counteracts oxidative stress and nerve growth factor
deficit in early experimental diabetic neuropathy.
Obrosova IG, Fathallah L, Stevens MJ. Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Michigan Medical Center, 1150 West Medical Center Drive, MSRB 2, Room 5570, Ann Arbor, Michigan 48109-0678, USA. iobrosso@umich.edu Oxidative stress has a key role in the pathogenesis of diabetic
complications. We have previously reported that taurine (T), which is
known to counteract oxidative stress in tissues (lens, kidney, retina) of
diabetic rats, attenuates nerve blood flow and conduction deficits in
early experimental diabetic neuropathy (EDN). The purpose of this study
was to evaluate whether dietary T supplementation counteracts oxidative
stress and the nerve growth factor (NGF) deficit in the diabetic
peripheral nerve. The experiments were performed in control rats and
streptozotocin-diabetic rats fed standard or 1% T-supplemented diets for 6
weeks. All measurements were performed in the sciatic nerve.
Malondialdehyde (MDA) plus 4-hydroxyalkenals (4-HA) were quantified with
N-methyl-2-phenylindole. GSH, GSSG, dehydroascorbate (DHAA), and ascorbate
(AA) were assayed spectrofluorometrically, T by reverse-phase HPLC, and
NGF by ELISA. MDA plus 4-HA concentration (mean +/- SEM) was increased in
diabetic rats (0.127 +/- 0.006 vs 0.053 +/- 0.003 micromol/g in controls,
P < 0.01), and this increase was partially prevented by T (0.096 +/-
0.004, P < 0.01 vs untreated diabetic group). GSH levels were similarly
decreased in diabetic rats treated with or without taurine vs controls.
GSSG levels were similar in control and diabetic rats but were lower in
diabetic rats treated with T (P < 0.05 vs controls). AA levels were
decreased in diabetic rats (0.133 +/- 0.015 vs 0.219 +/- 0.023 micromol/g
in controls, P < 0.05), and this deficit was prevented by T. DHAA/AA
ratio was increased in diabetic rats vs controls (P < 0.05), and this
increase was prevented by T. T levels were decreased in diabetic rats (2.7
+/- 0.16 vs 3.8 +/- 0.1 micromol/g in controls, P < 0.05) and were
repleted by T supplementation (4.2 +/- 0.3). NGF levels were decreased in
diabetic rats (2.35 +/- 0.20 vs 3.57 +/- 0.20 ng/g in controls, P <
0.01), and this decrease was attenuated by T treatment (3.16 +/- 0.28, P
< 0.05 vs diabetic group). In conclusion, T counteracts oxidative
stress and the NGF deficit in early EDN. Antioxidant effects of T in
peripheral nerve are, at least in part, mediated through the ascorbate
system of antioxidative defense. The findings are consistent with the
important role for oxidative stress in impaired neurotrophic support in
EDN. MeSH Terms:
From PubMed | |
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| 39 | Oxidant and antioxidant systems in niddm patients: influence of
vitamin E supplementation.
Gokkusu C, Palanduz S, Ademoglu E, Tamer S. Department of Biochemistry, Istanbul Faculty of Medicine, University of Istanbul, Capa, Turkey. cahgok@istanbul.edu.tr Free radical-mediated oxidative stress has been implicated in adverse tissue changes in a number of diseases. In view of the role of oxidative processes in non-insulin dependent diabetes mellitus (NIDDM), in this study, we investigated the oxidant and antioxidant status of plasma in patients with NIDDM and the effect of vitamin E (800 lU/day) supplementation on oxidative stress, antioxidant defense system, fructosamine levels and insulin action. Thirty controls and 40 NIDDM patients were studied. In controls and patients, plasma lipids, vitamin E, lipid peroxide, total thiols (t-SH), superoxide peroxidase (SOD) and glutathione peroxidase (GPx) were measured in the basal state and after vitamin E (800 IU/d) supplementation for a month. All lipids and lipid fractions in plasma were significantly decreased, whereas the HDL-C level was changed in diabetic patients supplemented with vitamin E when compared with baseline values. Vitamin E administration also significantly reduced fasting glucose and fructosamine levels, whereas increased significantly reduced fasting glucose and fructosamine levels, whereas increased significantly plasma C-peptide and insulin levels (p < 0.01, p < 0.001, respectively). Following vitamin E supplementation, TBARs levels were found to be significantly lower (p < 0.001) than the baseline value NIDDM patients are. On the other hand, activities of GPx and SOD were significantly higher (p < 0.001) than baseline values. A similar trend was observed for total thiols contents, but in this case, the increase was not significant. In conclusion, this study demonstrates that vitamin E improved beta-cell function and increased plasma insulin and C-peptide levels, possibly by inducing the antioxidant capacity of the organism and/or reducing the peripheral resistance in NIDDM. Long-term studies are needed to demonstrate the beneficial effects of vitamin E on treatment/prevention of NIDDM. MeSH Terms:
From PubMed | |
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| 40 | The effect of Glurenorm (gliquidone) on lenses and skin in
experimental diabetes.
Yarat A, Tunali T, Yanardag R, Gursoy FO, Sacan OO, Emekli N, Utuner A,
Ergenekon G. Department of Biochemistry, Faculty of Dentistry, Marmara University, Istanbul, Turkey. yarat@marun.edu.tr The aim of this study was to investigate the effect of administering Glurenorm (gliquidone, 10 mg/kg) on the lenses and skins of streptozotocin-induced diabetic rats. The drug was given to both diabetic and control rats daily, until the end of the experiment, at day 42. The drug was administered to one diabetic and one control group from day 0 and for the other diabetic and control groups from day 14. On day 42, cardiac blood samples, skin samples, and lenses were taken from each rat. Blood glucose (BG) was measured by the o-toluidine method. The total protein, nonenzymatic glycosylation of proteins (NEG), lipid peroxidation (LPO), and glutathione (GSH) levels in the lens and skin homogenates were determined by the Lowry, thiobarbituric acid, Ledwozwy, and Ellman methods, respectively. Laemmli SDS polyacrylamide gel electrophoresis was also carried out on the lens or skin homogenates. After 42 d, Glurenorm given to the diabetic rats produced (i) significant reductions in BG, NEG, and total protein in the lenses; (ii) significant increases in GSH levels in the lenses; (iii) and no significant results in the skin. The body weights of the drug group dropped relative to day 0, but not significantly. SDS polyacrylamide gel electrophoresis revealed no significant differences in any of the protein bands between any of the groups. In the lenses, the gains in turns of reduced NEG and increased GSH may have been offset by the reduction in protein. MeSH Terms:
From PubMed | |
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| 41 | Antioxidant properties of calcium dobesilate in ischemic/reperfused
diabetic rat retina.
Szabo ME, Haines D, Garay E, Chiavaroli C, Farine JC, Hannaert P, Berta
A, Garay RP. Department of Ophthalmology, School of Medicine, University of Debrecen, Debrecen, Hungary. Calcium dobesilate possesses antioxidant properties and protects against capillary permeability by reactive oxygen species in the rat peritoneal cavity, but whether a similar action can take place in the diabetic rat retina is unknown. We investigated the oral treatment of diabetic rats with calcium dobesilate on the prevention of free radical-mediated retinal injury induced by ischemia/reperfusion (90 min ischemia followed by 3 min and/or 24 h of reperfusion). Streptozotocin-induced diabetic rats were orally treated with 50 and 100 mg/kg of calcium dobesilate for 10 days (n=12 in each group). In the first series of studies, calcium dobesilate was found to significantly reduce the maldistribution of ion content in diabetic ischemic/reperfused rat retina. Thus, in diabetic rats treated with 100 mg/kg/day calcium dobesilate, ischemia/reperfusion provoked: (i) 27.5% increase in retinal Na(+) content compared to 51.8% in the vehicle-treated group (P<0.05), and (ii) 59.6% increase in retinal Ca(2+) content compared to 107.1% in vehicle-treated animals (P<0.05). In the second series of studies, calcium dobesilate was found to significantly protect diabetic rat retina against inhibition of Na(+)/K(+)-ATPase and Ca(2+)/Mg(2+)-ATPase activities by ischemia/reperfusion (54% and 41% reduction, respectively, with 100 mg/kg of calcium dobesilate) and also against changes in retinal ATP, reduced glutathione (GSH), and oxidized glutathione (GSSG) contents. In the third series of experiments, rats treated with 100 mg/kg of calcium dobesilate reduced the hydroxyl radical signal intensity to 41% (measured by electron paramagnetic resonance), induced by ischemia/reperfusion in diabetic rat retina. Finally, 100 mg/kg calcium dobesilate significantly reduced retinal edema (measured by the thickness of the inner plexiform layer) in diabetic rats. In conclusion, oral treatment with calcium dobesilate significantly protected diabetic rat retina against oxidative stress induced by ischemia/reperfusion. Whether the antioxidant properties of calcium dobesilate explain, at least in part, its beneficial therapeutic effects in diabetic retinopathy deserves further investigation. MeSH Terms:
From PubMed | |
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| 42 | Monotherapy with metformin: does it improve hypoxia in type 2
diabetic patients?
Cosic V, Antic S, Pesic M, Jovanovic O, Kundalic S, Djordjevic VB.
Centre of Medical Biochemistry, Clinical Centre Nis, Yugoslavia. cosic@bankerinter.net Metformin reduces blood glucose levels predominantly by inhibiting hepatic gluconeogenesis, although it also may enhance insulin receptor number or activity. The full effects of metformin are still poorly understood. In this study the effects of metformin on plasma xanthine oxidase (XO) activity, thiobarbituric acid-reactive substance (TBARS), lactate and fructosamine concentration as well as erythrocyte antioxidant enzyme activities were investigated in 46 patients with type 2 diabetes mellitus. All parameters were measured simultaneously just before metformin therapy (T0), 1 month (T1) and 2 months (T2) later. Results were compared with placebo and control group. We noted significant decrease in XO activity and in TBARS concentration (p<0.001) during monotherapy with metformin vs. placebo and T0 group. A significant correlation was observed between the activity of XO and the concentration of fructosam | |