Arginine and Lysine Supplementation Potentiates the Beneficial β-Hydroxy ß-Methyl Butyrate (HMB) Effects on Skeletal Muscle in a Rat Model of Diabetes

Skeletal muscle is the key tissue for maintaining protein and glucose homeostasis, having a profound impact on the development of diabetes. Diabetes causes deleterious changes in terms of loss of muscle mass, which will contribute to reduced glucose uptake and therefore progression of the disease. Nutritional approaches in diabetes have been directed to increase muscle glucose uptake, and improving protein turnover has been at least partially an oversight. In muscle, β-hydroxy β-methyl butyrate (HMB) promotes net protein synthesis, while arginine and lysine increase glucose uptake, albeit their effects on promoting protein synthesis are limited. This study evaluates if the combination of HMB, lysine, and arginine could prevent the loss of muscle mass and function, reducing the progression of diabetes. Therefore, the combination of these ingredients was tested in vitro and in vivo. In muscle cell cultures, the supplementation enhances glucose uptake and net protein synthesis due to an increase in the amount of GLUT4 transporter and stimulation of the insulin-dependent signaling pathway involving IRS-1 and Akt. In vivo, using a rat model of diabetes, the supplementation increases lean body mass and insulin sensitivity and decreases blood glucose and serum glycosylated hemoglobin. In treated animals, an increase in GLUT4, creatine kinase, and Akt phosphorylation was detected, demonstrating the synergic effects of the three ingredients. Our findings showed that nutritional formulations based on the combination of HMB, lysine, and arginine are effective, not only to control blood glucose levels but also to prevent skeletal muscle atrophy associated with the progression of diabetes.

Carbohydrate Metabolism in Diabetic Rat’s Heart – The Effects of Acetylsalicylic Acid and Heat Preconditioning as HSP70 Inducers

The myocardium of diabetic subjects displays reduced HSP70 protein level and weak myocardial protection. However, the heart possesses an ability to produce heat shock proteins (HSPs) after exposure to sublethal heat stress. Acetylsalicylicacid (ASA) has the property of pharmacological induction of HSPs. We evaluated the common effects of single dose ASA-pretreatment, prior to heat preconditioning (HP), over carbohydrate metabolism-related enzymes and substrates in the heart of diabetic rats. Streptozotocin-diabetes caused significant decrease of HSP70 protein level, stimulation of the gluconeogenic processes and inhibition of glycolytic processes in the heart. HP-diabetic hearts have significantly higher HSP70 protein level, lower glycogen, glucose-6-phosphate content, glycogen phosphorylase and hexokinase activity, and higher glucose levels and PFK activity. ASA-pretreatment of HP-diabetic animals caused additional increase of HSP70, additional decrease of glycogen, glucose-6-phosphate, glycogen phosphorylase and hexokinase, and additional increase of glucose and PFK in the heart. In conclusion, HP is physiological inducer of HSP70 level in heart and tends to reverse carbohydrate - related disturbances in diabetic rats. ASA, given prior to HP, is a potent HSP70 co-inducer and causes additional increase of HSP70 protein level in heart. ASA, given in a combination to HP, have shown more evident protective effects against subsequent intense of stress.

d-Galactose Decreases Anion Exchange Capability through Band 3 Protein in Human Erythrocytes

d-Galactose (d-Gal), when abnormally accumulated in the plasma, results in oxidative stress production, and may alter the homeostasis of erythrocytes, which are particularly exposed to oxidants driven by the blood stream. In the present investigation, the effect of d-Gal (0.1 and 10 mM, for 3 and 24 h incubation), known to induce oxidative stress, has been assayed on human erythrocytes by determining the rate constant of SO₄²⁻ uptake through the anion exchanger Band 3 protein (B3p), essential to erythrocytes homeostasis. Moreover, lipid peroxidation, membrane sulfhydryl groups oxidation, glycated hemoglobin (% A1c), methemoglobin levels (% MetHb), and expression levels of B3p have been verified. Our results show that d-Gal reduces anion exchange capability of B3p, involving neither lipid peroxidation, nor oxidation of sulfhydryl membrane groups, nor MetHb formation, nor altered expression levels of B3p. d-Gal-induced %A1c, known to crosslink with B3p, could be responsible for rate of anion exchange alteration. The present findings confirm that erythrocytes are a suitable model to study the impact of high sugar concentrations on cell homeostasis; show the first in vitro effect of d-Gal on B3p, contributing to the understanding of mechanisms underlying an in vitro model of aging; demonstrate that the first impact of d-Gal on B3p is mediated by early Hb glycation, rather than by oxidative stress, which may be involved on a later stage, possibly adding more knowledge about the consequences of d-Gal accumulation.

Prevention of α-crystallin glycation and aggregation using l-lysine results in the inhibition of in vitro catalase heat-induced-aggregation and suppression of cataract formation in the diabetic rat

The principle role of α-crystallin is chaperoning activity that protect s other proteins against different stresses. High glucose concentration induces the osmotic stress and results in biomacromolecules glycation, which is subsequently cause their conformational and functional changes. Here, the roles of l-lysine (Lys) on the prevention of α-crystallin glycation in both in vitro and in vivo conditions are investigated. The catalase (CAT) activity was considered as a marker of α-crystallin functionality in both conditions. Streptozotocin-induced diabetic rats were treated with 0.1% of the Lys in drinking water. The purified α-crystallin was also incubated with glucose, in the presence or absence of the Lys and its structure-function was compared. The results showed that the visual cataract score was significantly lower in the diabetic rats treated with Lys. After Lys treatment, CAT, superoxide dismutase, aldose reductase and other biochemical parameters in the lens and serum of the diabetic rats returned to the normal value. Formation of the advanced glycation endproducts (AGEs), protein cross-linking, and the hydrophobicity of α-crystallin were changed due to glycation, but they were reversed by Lys treatment. The glycated α-crystallin lost its chaperone activity against heat denatured-CAT, but in the presence of Lys, it preserved its activity and prevented CAT aggregation. In conclusion, Lys treatment significantly inhibited the progression of diabetic cataract in rats. These effects were due to the Lys antiglycating and antioxidant effects, in addition to its protective effect against α-crystallin chaperoning activity.

Heat preconditioning and aspirin treatment attenuate hepatic carbohydrate-related disturbances in diabetic rats

Heat preconditioning (HP) is a powerful adaptive and protective phenomenon and induces moderation of diabetic alterations in glycogen metabolism of rats. Aspirin (acetylsalicylic acid, ASA), as a multifunctional drug has also been reported to exert hypoglycemic effects in the treatment of diabetes. We estimated the effect of HP (45 min/41 ± 0.5 °C/24 h recovery) and single dose aspirin (100 mg/kg b.w./i.p) treatment over carbohydrate-related enzymes and substrates in a time-dependent (2, 7 and 14 days) manner of duration of diabetes in the liver of rats. Heat preconditioning resulted in lower liver glucose concentration, but higher HK activity and lower G6P-ase; very evident and significantly higher glycogen content and GPho-ase activity, as well as very evident and significantly lower F1,6BP-ase and higher PFK activity compared to control diabetic animals. Aspirin pretreatment of HP-diabetic animals is manifested with significantly lower blood and liver glucose, higher G6P concentration, lower G6P-ase and HK activity as well as higher Glk content and GPho-ase activity, compared both to diabetic and HP-diabetic animals. In conclusion, both HP and aspirin, as physiological and pharmacological inductors of HSP70, respectively, attenuate the carbohydrate-related disturbances in diabetic rats, with almost tendency to normalisation to the control values for most of the estimated parameters.

Current and future therapies for addressing the effects of inflammation on HDL cholesterol metabolism

Cardiovascular disease (CVD) is a major cause of morbidity and mortality worldwide. Inflammatory processes arising from metabolic abnormalities are known to precipitate the development of CVD. Several metabolic and inflammatory markers have been proposed for predicting the progression of CVD, including high density lipoprotein cholesterol (HDL-C). For ~50 years, HDL-C has been considered as the atheroprotective 'good' cholesterol because of its strong inverse association with the progression of CVD. Thus, interventions to increase the concentration of HDL-C have been successfully tested in animals; however, clinical trials were unable to confirm the cardiovascular benefits of pharmaceutical interventions aimed at increasing HDL-C levels. Based on these data, the significance of HDL-C in the prevention of CVD has been called into question. Fundamental in vitro and animal studies suggest that HDL-C functionality, rather than HDL-C concentration, is important for the CVD-preventive qualities of HDL-C. Our current review of the literature positively demonstrates the negative impact of systemic and tissue (i.e. adipose tissue) inflammation in the healthy metabolism and function of HDL-C. Our survey indicates that HDL-C may be a good marker of adipose tissue health, independently of its atheroprotective associations. We summarize the current findings on the use of anti-inflammatory drugs to either prevent HDL-C clearance or improve the function and production of HDL-C particles. It is evident that the therapeutic agents currently available may not provide the optimal strategy for altering HDL-C metabolism and function, and thus, further research is required to supplement this mechanistic approach for preventing the progression of CVD.

LINKED ARTICLES

This article is part of a themed section on Targeting Inflammation to Reduce Cardiovascular Disease Risk. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.22/issuetoc and http://onlinelibrary.wiley.com/doi/10.1111/bcp.v82.4/issuetoc.

Analgesic antipyretic use among young children in the TEDDY study: no association with islet autoimmunity

BACKGROUND

The use of analgesic antipyretics (ANAP) in children have long been a matter of controversy. Data on their practical use on an individual level has, however, been scarce. There are indications of possible effects on glucose homeostasis and immune function related to the use of ANAP. The aim of this study was to analyze patterns of analgesic antipyretic use across the clinical centers of The Environmental Determinants of Diabetes in the Young (TEDDY) prospective cohort study and test if ANAP use was a risk factor for islet autoimmunity.

METHODS

Data were collected for 8542 children in the first 2.5 years of life. Incidence was analyzed using logistic regression with country and first child status as independent variables. Holm's procedure was used to adjust for multiplicity of intercountry comparisons. Time to autoantibody seroconversion was analyzed using a Cox proportional hazards model with cumulative analgesic use as primary time dependent covariate of interest. For each categorization, a generalized estimating equation (GEE) approach was used.

RESULTS

Higher prevalence of ANAP use was found in the U.S. (95.7%) and Sweden (94.8%) compared to Finland (78.1%) and Germany (80.2%). First-born children were more commonly given acetaminophen (OR 1.26; 95% CI 1.07, 1.49; p = 0.007) but less commonly Non-Steroidal Anti-inflammatory Drugs (NSAID) (OR 0.86; 95% CI 0.78, 0.95; p = 0.002). Acetaminophen and NSAID use in the absence of fever and infection was more prevalent in the U.S. (40.4%; 26.3% of doses) compared to Sweden, Finland and Germany (p < 0.001). Acetaminophen or NSAID use before age 2.5 years did not predict development of islet autoimmunity by age 6 years (HR 1.02, 95% CI 0.99-1.09; p = 0.27). In a sub-analysis, acetaminophen use in children with fever weakly predicted development of islet autoimmunity by age 3 years (HR 1.05; 95% CI 1.01-1.09; p = 0.024).

CONCLUSIONS

ANAP use in young children is not a risk factor for seroconversion by age 6 years. Use of ANAP is widespread in young children, and significantly higher in the U.S. compared to other study sites, where use is common also in absence of fever and infection.

Inhibitory Effect of Crocin(s) on Lens α-Crystallin Glycation and Aggregation, Results in the Decrease of the Risk of Diabetic Cataract

The current study investigates the inhibitory effect of crocin(s), also known as saffron apocarotenoids, on protein glycation and aggregation in diabetic rats, and α-crystallin glycation. Thus, crocin(s) were administered by intraperitoneal injection to normal and streptozotocin-induced diabetic rats. The cataract progression was recorded regularly every two weeks and was classified into four stages. After eight weeks, the animals were sacrificed and the parameters involved in the cataract formation were measured in the animal lenses. Some parameters were also determined in the serum and blood of the rats. In addition, the effect of crocin(s) on the structure and chaperone activity of α-crystallin in the presence of glucose was studied by different methods. Crocin(s) lowered serum glucose levels of diabetic rats and effectively maintained plasma total antioxidants, glutathione levels and catalase activity in the lens of the animals. In the in vitro study, crocin(s) inhibited α-crystallin glycation and aggregation. Advanced glycation end products fluorescence, hydrophobicity and protein cross-links were also decreased in the presence of crocin(s). In addition, the decreased chaperone activity of α-crystallin in the presence of glucose changed and became close to the native value by the addition of crocin(s) in the medium. Crocin(s) thus showed a powerful inhibitory effect on α-crystallin glycation and preserved the structure-function of this protein. Crocin(s) also showed the beneficial effects on prevention of diabetic cataract.

Impact of systemic inflammation and autoimmune diseases on apoA-I and HDL plasma levels and functions

The cholesterol of high-density lipoproteins (HDLs) and its major proteic component, apoA-I, have been widely investigated as potential predictors of acute cardiovascular (CV) events. In particular, HDL cholesterol levels were shown to be inversely and independently associated with the risk of acute CV diseases in different patient populations, including autoimmune and chronic inflammatory disorders. Some relevant and direct anti-inflammatory activities of HDL have been also recently identified targeting both immune and vascular cell subsets. These studies recently highlighted the improvement of HDL function (instead of circulating levels) as a promising treatment strategy to reduce inflammation and associated CV risk in several diseases, such as systemic lupus erythematosus and rheumatoid arthritis. In these diseases, anti-inflammatory treatments targeting HDL function might improve both disease activity and CV risk. In this narrative review, we will focus on the pathophysiological relevance of HDL and apoA-I levels/functions in different acute and chronic inflammatory pathophysiological conditions.

High dose of aspirin moderates diabetes-induced changes of heart glycogen/glucose metabolism in rats

Aspirin (ASA), as a multifunctional drug has been used as a hypoglycaemic agent in the treatment of diabetes and severe hyperglycaemia and has been established as a secondary strategy which may prevent many cardiovascular events. In this study we investigated high dose (100 mg/kg b.w./i.p) and time-dependent (2, 7 and 14 days) effects of ASA on the heart key enzymes and substrates from glycogen/glucose metabolism in control and diabetic rats. The results accomplished demonstrated that ASA significantly potentiates glycogen accumulation, as well as decreased blood glucose level and heart glycolytic potential in control rats. The treatment of diabetic rats with ASA caused moderation of the diabetic complication-significant inhibition of glycogen accumulation, lowering of blood glucose, as well as elevation of glycolytic potential. In conclusion, we propose that use of high-dose of ASA has anabolic effects in control rats and reduces heart glycogen glucose complications in diabetic rats. The moderation of diabetes-induced changes is time-dependent and involves reduction of glycogenogenesis and inhibited depression of glycolysis, with a tendency to maintenance control values.

Exercise Training and Grape Seed Extract Co-Administration Improves Lipid Profile, Weight Loss, Bradycardia, and Hypotension of STZ-Induced Diabetic Rats

BACKGROUND

Exercise Training (ET) and Grape Seed Extract (GSE) as an antioxidant have many positive effects on controlling diabetes mellitus and its complications.

OBJECTIVES

This study aimed to determine the effects of GSE alone or combined with ET on body weight, plasma lipid profile, blood pressure, and heart rate in STZ-induced diabetic rats.

METHODS

IN THIS STUDY, MALE WISTAR RATS WERE RANDOMLY ASSIGNED TO FIVE GROUPS: sedentary control, sedentary diabetic, trained diabetic, GSE treated sedentary diabetic, and GSE treated trained diabetic. ET was conducted on the treadmill daily for 8 weeks. One way ANOVA followed by LSD test was used for statistical analysis.

RESULTS

Reduction of body weight, high density lipoproteins, heart rate, and systolic blood pressure and increment of total cholesterol, triglyceride, low density lipoprotein, and very low density lipoproteins were observed after STZ injection. Co-administration of GSE and ET had more positive effects on lipid profile compared to each method alone. In addition, GSE and ET modified heart rate partially, while their combination was more effective in improvement of heart rat in conscious rats. On the other hand, administration of ET or GSE alone did not affect systolic blood pressure and body weight, while their combination restored systolic blood pressure completely and improved body weight partially.

CONCLUSIONS

The study findings indicated that ET combined with GSE had more beneficial effects compared to each one alone on the complications of STZ induced diabetes. This may constitute a convenient and inexpensive therapeutic approach to diabetic complications.

Oat Protects against Diabetic Nephropathy in Rats via Attenuating Advanced Glycation End Products and Nuclear Factor Kappa B

Oat, a rich source of soluble fiber, was considered to have a possible preventive effect on the progression of diabetic nephropathy. The present study aimed to assess this preventive activity in a rat model of diabetic nephropathy. Adult Wister rats were injected by streptozotocin (65 mg/kg). Animals were fed with normal diet or with a diet containing 20% oat (W/W) for 21 weeks. At the end of 21 weeks, all the kidney tissues were collected for various examinations. Our results suggested that oat could decrease the Scr and glucose level in blood of diabetic rats significantly (P < 0.05), and increase the creatinine clearance (P < 0.01). In histopathological examination, oat-fed rats showed a significant decrease in glomerulus segmented sclerosis and incidence of tubule vacuolar degeneration. By ELISA, we reported that oat feeding resulted in decreasing the levels of IL-6 and AGE in serum and kidney homogenate. In addition, the levels of oxidative stress markers were markedly improved as a result of oat feeding. Furthermore, using EMSA, we showed that oat attenuated the activation of NF-κB. Using RT-PCR, we found that oat could downregulate the TGF-β1 and RAGE expression at mRNA levels. This study suggests that oat can suppress diabetic nephropathy in rats effectively and may slow down the renal fibrosis by the disruption of the detrimental AGE-RAGE-NFκB axis.

Effect of crocin on the insulin resistance and lipid profile of streptozotocin-induced diabetic rats

Crocin is the only water soluble carotenoid in nature, and it has a known powerful antioxidant activity. The aim of this work was to investigate the hypoglycemic and hypolipidemic effects of crocin in streptozotocin (STZ)-induced type 2 diabetic rats. Neonatal male Wistar rats (2-5 days old) were randomly divided into five groups. Three groups were intraperitoneally injected with STZ (90 mg/kg body weight). Among them, two groups were treated with intraperitoneal injection of crocin (50 or 100 mg/kg), and the third group was treated with vehicle only. Two control groups were also considered, and one of them was treated with crocin. After 5 months, their blood and urine samples were collected, and the animals were sacrified. The results indicate a significant lower body weight (P < 0.001) and abnormal parameters in the diabetic rats compared with the normal group. An administration of both doses of crocin significantly decreased the levels of serum glucose, advanced glycation end products, triglyceride, total cholesterol, and low-density lipoprotein and increased the high-density lipoprotein in the diabetic rats. The treatments were also effective in decreasing HbA1c and microalbuminuria, as well as homeostatic model assessment for insulin resistance as a measure of insulin resistance in the diabetic rats.

Investigation of the mechanism(s) involved in decreasing increased fibrinogen activity in hyperglycemic conditions using L-lysine supplementation

INTRODUCTION

Fibrinogen is a plasma glycoprotein that participates in the hemostasis system. Its malfunction has been reported as a consequence of diabetic complications. In this study, the inhibitory effect of L-Lysine (Lys) on the nonenzymatic glycation of fibrinogen was investigated in both in vitro and in vivo conditions.

MATERIALS AND METHODS

Fibrinogen was incubated with glucose in the presence or absence of Lys. Then, its structure was studied by fluorescence spectroscopy, circular dichroism, and electrophoresis. The Clauss method was used to determine fibrinogen activity. In addition, one of the two groups of type 2 diabetic patients receiving ordinary treatment was additionally treated with Lys for 3 months. Fibrinogen activity and some other parameters were evaluated in their plasma.

RESULTS

The results indicated increases in the activity of glycated fibrinogen in both of the in vivo and in vitro experiments. Advanced glycation end products were increased by time, as shown using fluorometry in both the plasma of the diabetic patients and the incubation medium of protein with glucose. The circular dichroism spectra showed some changes in the fibrinogen secondary and tertiary structures after glycation. The electrophoretic mobility of the glycated fibrinogen changed and the cross-link formation between the fibrinogen subunits due to glycation was observed. Lys inhibited all of the mentioned fibrinogen changes both in the in vitro experiments and after its administration to the diabetic patients.

CONCLUSION

Lys, as an inhibitor of protein glycation, improved fibrinogen's structure and function, both in vitro and in vivo.

Effect of chemical chaperones on glucose-induced lysozyme modifications

Nonenzymatic glycation of biomacromolecules occurs due to the diabetes mellitus and ageing. A number of small molecules, known as chemical chaperones, stabilize protein conformation against thermal and chemically induced denaturation. These compounds are including: polyamines (e.g. spermine and spermidine), amino acids (e.g. lysine) and polyols (e.g. glycerol). In this study the effect of spermidine (Spd), spermine (Spm), and glycerol on glycation, structure and function of lysozyme (LZ), as an extra-cellular protein, by different techniques is investigated. LZ is incubated with or without glucose (50 or 100 mM) in the absence or presence of Spd/Spm/glycerol at 37 °C up to 16 weeks. All the observed changes of glycated-LZ in comparison with the native protein, including: increased fluorescence emission, alteration in the secondary and tertiary structure, and reduced electrophoretic mobility- indicate its structural changes that are accompanied with its reduced activity. Glucose in the presence or absence of Spd induces the protein dimerization, but glucose plus Spm induces its trimmerization. In contrast, glycerol inhibits the LZ glycation and prevents the large changes on its structure and function. Glucose binds lysine residues, decreases the protein positive charges and induces some alterations in its structure and activity. Polyamines also directly bind to LZ, increase its positive charges and hence induce more glycation; more conformational changes, oligomerization and its inactivation in the presence of glucose, but glycerol affect the protein environment and preserve protein from these harmful effects.

Low dose aspirin therapy decreases blood glucose levels but does not prevent type i diabetes-induced bone loss

BACKGROUND

Diabetes is strongly associated with increased fracture risk. During T1-diabetes onset, levels of blood glucose and pro-inflammatory cytokines (including TNFα) are increased. At the same time, levels of osteoblast markers are rapidly decreased and stay decreased 40 days later at which point bone loss is clearly evident. Inflammation is known to suppress bone formation and induce bone loss. Previous co-culture studies indicate that diabetic bone is inflamed and diabetic bone marrow is capable of enhancing osteoblast death in vitro. Here we investigate a commonly used non-steroidal anti-inflammatory drug, aspirin, to prevent T1-diabetic bone loss in vivo.

METHODS

We induced diabetes in 16-week-old male C57BL/6 mice and administered aspirin in the drinking water.

RESULTS

Our results demonstrate that aspirin therapy reduced diabetic mouse non-fasting blood glucose levels to less than 400 mg/dl, but did not prevent trabecular and cortical bone loss. In control mice, aspirin treatment increased bone formation markers but did not affect markers of bone resorption or bone density/volume. In diabetic mice, bone formation markers and bone density/volume are decreased and unaltered by aspirin treatment. Bone resorption markers, however, are increased and 2-way ANOVA analysis demonstrates an interaction between aspirin treatment and diabetes (p<0.007). Aspirin treatment did not prevent the previously reported diabetes-induced marrow adiposity.

CONCLUSION

Taken together, our results suggest that low dose aspirin therapy does not negatively impact bone density in control and diabetic mice, but could potentially increase bone resorption in T1-diabetic mice.

The effect of hot-tub therapy on serum Hsp70 level and its benefit on diabetic rats: a preliminary report

PURPOSE

To carry out a preliminary study examining the efficacy of long-term hot-tub therapy (HTT) in the improvement of diabetic complications on streptozotocin-induced diabetic rats.

MATERIALS AND METHODS

Male Wistar rats were immersed mid-sternum in a circulating water bath (42 degrees C for 30 min) to obtain a core body temperature of 41 degrees C; this process was repeated three times a week for 5 months. The blood was collected every month. Multiple parameters were examined for all rats including heat shock protein (Hsp70) level, serum glucose and insulin concentrations, advanced glycation end product (AGE) and glycated haemoglobin (HbA1c) formation, lipid profile and antioxidant defence system. Additionally, the chaperoning capacity of glycated Hsp70 was evaluated based on in vitro studies in which the refolding of denatured luciferase was compared to refolding by native Hsp70.

RESULTS

HTT-treated diabetic rats showed a significant improvement in lipid profile, antioxidant capacity, insulin secretion and serum Hsp70 level and a significant decrease in AGE formation compared to the untreated diabetic rats. However, HTT had a borderline significant effect on weight and fasting blood glucose. Glycated Hsp70 lost its chaperoning ability to reactivate the denatured luciferase.

CONCLUSION

A decrease in complications in diabetic rats after hot-tub therapy is shown here. An increase in the extracellular Hsp70 level due to HTT was observed. This increase may serve to protect the structure of proteins (e.g. preventing AGE formation), and the observed beneficial effects may be related to it.

Spectroscopic studies of the interaction of aspirin and its important metabolite, salicylate ion, with DNA, A·T and G·C rich sequences

Among different biological effects of acetylsalicylic acid (ASA), its anticancer property is controversial. Since ASA hydrolyzes rapidly to salicylic acid (SA), especially in the blood, interaction of both ASA and SA (as the small molecules) with ctDNA, oligo(dA·dT)15 and oligo(dG·dC)15, as a possible mechanism of their action, is investigated here. The results show that the rate of ASA hydrolysis in the absence and presence of ctDNA is similar. The spectrophotometric results indicate that both ASA and SA cooperatively bind to ctDNA. The binding constants (K) are (1.7±0.7)×10(3) M(-1) and (6.7±0.2)×10(3) M(-1) for ASA and SA, respectively. Both ligands quench the fluorescence emission of ethidium bromide (Et)-ctDNA complex. The Scatchard plots indicate the non-displacement based quenching (non-intercalative binding). The circular dichroism (CD) spectra of ASA- or SA-ctDsNA complexes show the minor distortion of ctDNA structure, with no characteristic peaks for intercalation of ligands. Tm of ctDNA is decreased up to 3°C upon ASA binding. The CD results also indicate more distortions on oligo(dG·dC)15 structure due to the binding of both ASA and SA in comparison with oligo(dA·dT)15. All data indicate the more affinity for SA binding with DNA minor groove in comparison with ASA which has more hydrophobic character.

Increased serum HSP70 levels are associated with the duration of diabetes

The evolutionary conserved family of heat shock proteins (HSP) is responsible for protecting cells against different types of stress, including oxidative stress. Although the levels of HSPs can be readily measured in blood serum, the levels of HSP70 in patients with different durations of diabetes have not been studied before. We quantified serum HSP70 levels in a healthy control group (n = 36) and two groups of type 2 diabetic patients, defined as newly diagnosed diabetes (n = 36) and patients with diabetes duration of more than 5 years (n = 37). The clinical characteristics and biochemical parameters were evaluated in the studied population. We found that serum HSP70 levels were significantly higher in patients with diabetes when compared with controls (p < 0.001) and it was higher in patients with disease for more than 5 years than in newly diagnosed patients (p < 0.001). Serum HSP70 was inversely correlated with fasting blood sugar in patients with diabetes for more than 5 years (r = -0.500, p = 0.002), positively correlated with the history of hypertension in newly diagnosed patients (p < 0.001), and positively correlated with age in patients with diabetes (r = 0.531, p = 0.001). Serum level of HSP70 is significantly higher in patients with diabetes and correlates with the duration of disease. Higher HSP70 in prolonged diabetes versus newly diagnosed diabetes may be an indicator of metabolic derangement in the course of diabetes.

Combination of aspirin with telmisartan suppresses the augmented TGFbeta/smad signaling during the development of streptozotocin-induced type I diabetic nephropathy

Diabetic nephropathy (DN) is the most common indication for the development of end stage renal diseases. Inflammation is increasingly seen as the core process in the development of diabetes. Inflammatory markers e.g. NFkappaB (p65 levels), TNFalpha, COX-2 and TGFbeta-smad signaling are the key elements in the development of DN. Renin-angiotensin system suppressors like telmisartan have been used to treat DN, but they are not able to prevent completely because of development of resistance against them. Anti-inflammatory agents like, aspirin acts through both COX dependent and COX independent pathways. Hence, we thought that combining aspirin with telmisartan will be better therapeutic option in preventing the progression of nephropathy in diabetes. In the present study we studied the effect of this combination on inflammatory markers [COX-2, NFkappaB (p65 levels), TNFalpha], TGFbeta-smad expression in preventing the progression of streptozotocin-induced type I diabetic nephropathy. Treatment of aspirin significantly prevented the progression of nephropathy and inhibited the augmented COX-2, NFkappaB (p65 levels), TNFalpha, and TGFbeta-smad expression. Combination of aspirin with telmisartan resulted in a further decrease in the development of nephropathy and inflammatory markers in comparison to aspirin alone treatment. This is the first report which shows that aspirin in combination with telmisartan is more proficient in the treatment of diabetic nephropathy than any single drug therapy and involves the change in expression of inflammatory markers and TGFbeta-smad signaling.

XLF-III-43, a novel coumarin-aspirin compound, prevents diabetic nephropathy in rats via inhibiting advanced glycation end products

Advanced glycation end products (AGE) have been implicated in the pathogenesis of diabetic complications. The purpose of this study was to examine the novel coumarin-aspirin compound XLF-III-43 in the inhibition of AGE formation in diabetic nephropathy. In vitro analysis showed XLF-III-43 in a dose-dependent manner decreased glucose induced formation of glycation adducts on albumin and inhibited AGE-lysozyme crosslinking. The streptozotocin-induced diabetic rats were used to investigate the beneficial effects of XLF-III-43 treatment on diabetic nephropathy. Administration of XLF-III-43 significantly decreased (P<0.05) blood urea nitrogen and urinary albumin excretion. Moreover, XLF-III-43 ameliorated kidney hypertrophy, mesangial expansion and glomerulosclerosis in diabetic rats relative to untreated model group. These data correlated with decreased both AGE and downstream markers of AGE stress (TGF-beta1, CTGF, fibronectin and collagen IV fibrolysis) in kidneys of diabetic rats. These data support further development of XLF-III-43 for prevention of nephropathy via inhibition of AGE formation consequent to chronic hyperglycemia.