Attenuation of hyperglycemia and amadori products by aminoguanidine in alloxan-diabetic rabbits occurs via enhancement in antioxidant defenses and control of stress.

The micro- and macro-complications in diabetes mellitus (DM) mainly arise from the damage induced by Amadori and advanced glycation end products, as well as the released free radicals. The primary goal of DM treatment is to reduce the risk of micro- and macro-complications. In this study, we looked at the efficacy of aminoguanidine (AG) to prevent the production of early glycation products in alloxan-diabetic rabbits. Type1 DM was induced in rabbits by a single intravenous injection of alloxan (90 mg/kg body weight). Another group of rabbits was pre-treated with AG (100 mg/kg body weight) prior to alloxan injection; this was followed by weekly treatment with 100 mg/kg of AG for eight weeks. Glucose, insulin, and early glycation products (HbA1C and fructosamine) were measured in control, diabetic and AG treated diabetic rabbits. The effects of hyperglycemia on superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (Gpx), reduced glutathione (rGSH), nitric oxide, lipid peroxides, and protein carbonyl were investigated. Alloxan-diabetic rabbits had lower levels of SOD, CAT, Gpx, and rGSH than control rabbits. Nitric oxide levels were considerably greater. AG administration restored the activities of SOD, CAT, Gpx enzymes up to 70-80% and ameliorated the nitric oxide production. HbA1c and fructosamine levels were considerably lower in AG-treated diabetic rabbits. The observed control of hyperglycemia and amadori adducts in alloxan-diabetic rabbits by AG may be attributed to decrease of stress and restoration of antioxidant defenses.

Maternal lipids are associated with newborn adiposity, independent of GDM status, obesity and insulin resistance: a prospective observational cohort study.

OBJECTIVE: To determine the association between maternal lipaemia and neonatal anthropometrics in Malaysian mother-offspring pairs. DESIGN: Prospective observational cohort study. SETTING: Single tertiary multidisciplinary antenatal clinic in Malaysia. POPULATION: A total of 507 mothers: 145 with gestational diabetes mellitus (GDM); 94 who were obese with normal glucose tolerance (NGT) (pre-gravid body mass index, BMI ≥ 27.5 kg/m2 ), and 268 who were not obese with NGT. METHODS: Maternal demographic, anthropometric, and clinical data were collected during an interview/examination using a structured questionnaire. Blood was drawn for insulin, C-peptide, triglyceride (Tg), and non-esterified fatty acid (NEFA) during the 75-g 2-hour oral glucose tolerance test (OGTT) screening, and again at 36 weeks of gestation. At birth, neonatal anthropometrics were assessed and data such as gestational weight gain (GWG) were extracted from the records. MAIN OUTCOME MEASURES: Macrosomia, large-for-gestational-age (LGA) status, cohort-specific birthweight (BW), neonatal fat mass (NFM), and sum of skinfold thickness (SSFT) > 90th centile. RESULTS: Fasting Tg > 95th centile (3.6 mmol/L) at screening for OGTT was independently associated with LGA (adjusted odds ratio, aOR 10.82, 95% CI 1.26-93.37) after adjustment for maternal glucose, pre-gravid BMI, and insulin sensitivity. Fasting glucose was independently associated with a birthweight ratio (BWR) of >90th centile (aOR 2.06, 95% CI 1.17-3.64), but not with LGA status, in this well-treated GDM cohort with pre-delivery HbA1c of 5.27%. In all, 45% of mothers had a pre-gravid BMI of <23 kg/m2 and 61% had a pre-gravid BMI of ≤ 25 kg/m2 , yet a GWG of >10 kg was associated with a 4.25-fold risk (95% CI 1.71-10.53) of BWR > 90th centile. CONCLUSION: Maternal lipaemia and GWG at a low threshold (>10 kg) adversely impact neonatal adiposity in Asian offspring, independent of glucose, insulin resistance and pre-gravid BMI. These may therefore be important modifiable metabolic targets in pregnancy. TWEETABLE ABSTRACT: Maternal lipids are associated with adiposity in Asian babies independently of pre-gravid BMI, GDM status, and insulin resistance.

Inhibiting Effect of Zinc Oxide Nanoparticles on Advanced Glycation Products and Oxidative Modifications: a Potential Tool to Counteract Oxidative Stress in Neurodegenerative Diseases.

Advanced glycation end products (AGEs) are implicated in several central nervous system (CNS) pathologies including Alzheimer and Parkinson's diseases. In the face-off of AGE menace, we have attempted to investigate the zinc oxide nanoparticle (ZnONP) role in inhibition of AGE formation. Synthesized ZnONPs were used to investigate the inhibitory effects on AGE formation. The inhibitory effects of ZnONPs on AGE formation were determined by biophysical immunological and biochemical techniques. The results showed that ZnONP is a potential anti-glycating agent inhibiting AGE formation as well as protecting the protein structure from change. Therefore, our findings suggest ZnONPs may be used as a therapeutic in resolving the AGE role in CNS-related complications.

Methylglyoxal and Advanced Glycation End products: Insight of the regulatory machinery affecting the myogenic program and of its modulation by natural compounds.

Methylglyoxal (MG) is a reactive dicarbonyl intermediate and a precursor of advanced glycation end products (AGEs). The authors investigated the role played by AGEs in muscle myopathy and the amelioration of its effects by curcumin and gingerol. In addition to producing phenotypical changes, MG increased oxidative stress and reduced myotube formation in C2C12 cells. RAGE (receptor for AGEs) expression was up-regulated and MYOD and myogenin (MYOG) expressions were concomitantly down-regulated in MG-treated cells. Interestingly, AGE levels were higher in plasma (~32 fold) and muscle (~26 fold) of diabetic mice than in control mice. RAGE knock-down (RAGEkd) reduced the expressions of MYOD and MYOG and myotube formation in C2C12 cells. In silico studies of interactions between curcumin or gingerol and myostatin (MSTN; an inhibitor of myogenesis) and their observed affinities for activin receptor type IIB (ACVRIIB) suggested curcumin and gingerol reduce the interaction between MSTN and ACVRIIB. The findings of this study suggest enhanced AGE production and subsequent RAGE-AGE interaction obstruct the muscle development program, and that curcumin and gingerol attenuate the effect of AGEs on myoblasts.

DNA Glycation from 3-Deoxyglucosone Leads to the Formation of AGEs: Potential Role in Cancer Auto-antibodies.

The non-enzymatic glycation reaction results in the generation of free radicals which play an important role in the pathophysiology of aging, diabetes, and cancer. 3-Deoxyglucosone (3-DG) is a dicarbonyl species which may lead to the formation of advanced glycation end products (AGEs). 3-DG also reacts with free amino group of nucleic acids resulting in the formation of DNA-AGEs. While the establishment of nucleoside AGEs has been revealed before, no extensive studies have been done to probe the role of 3-DG in the generation of immunogenicity and induction of cancer auto-antibodies. In this study, we report the immunogenicity of AGEs formed by 3-DG-Arg-Fe(3+) system. Spectroscopic analysis and melting temperature studies suggest structural perturbations in the DNA as a result of modification. Immunogenicity of native and 3-DG-Arg-Fe(3+) DNA was probed in female rabbits. The modified DNA was highly immunogenic eliciting high-titer immunogen-specific antibodies, while the unmodified form was almost non-immunogenic. We also report the presence of auto-antibodies against 3-DG-Arg-Fe(3+)-modified DNA in the sera of patients with different types of cancers. The glycoxidative lesions were also detected in the lymphocyte DNA isolated from selected cancer patients. The results show structural perturbations in 3-DG-Arg-Fe(3+)-DNA generating new epitopes that render the molecule immunogenic.

Green synthesis of silver nanoparticles and characterization of their inhibitory effects on AGEs formation using biophysical techniques.

Advanced glycation end-products (AGEs) resulting from non-enzymatic glycation are one of the major factors implicated in secondary complications of diabetes. Scientists are focusing on discovering new compounds that may be used as potential AGEs inhibitors without affecting the normal structure and function of biomolecules. A number of natural and synthetic compounds have been proposed as AGE inhibitors. In this study, we investigated the inhibitory effects of AgNPs (silver nanoparticles) in AGEs formation. AgNPs (~30.5 nm) synthesized from Aloe Vera leaf extract were characterized using UV-Vis spectroscopy, energy-dispersive X-ray spectroscopy (EDX), high resolution-transmission electron microscopy, X-ray diffraction and dynamic light scattering (DLS) techniques. The inhibitory effects of AgNPs on AGEs formation were evaluated by investigating the degree of reactivity of free amino groups (lysine and arginine residues), protein-bound carbonyl and carboxymethyl lysine (CML) content, and the effects on protein structure using various physicochemical techniques. The results showed that AgNPs significantly inhibit AGEs formation in a concentration dependent manner and that AgNPs have a positive effect on protein structure. These findings strongly suggest that AgNPs may play a therapeutic role in diabetes-related complications.

Quercetin as a finer substitute to aminoguanidine in the inhibition of glycation products.

Non-enzymatic glycation is the addition of a free carbonyl group of a reducing sugar to the free amino groups of proteins, which results in the formation of early and advanced glycation end-products (AGEs). Glycation reaction is profoundly associated with diabetes and its secondary complications, such as nephropathy and neuropathy. Glyoxal is a carbonyl species that reacts rapidly with the free amino groups of proteins to form AGEs. While the formation of AGEs with various glycating agents has previously been demonstrated, no extensive studies have been conducted to assess the role of quercetin in all three stages of glycation (early, intermediate and late). In this study, we report the glycation of HSA (human serum albumin) and its characterization by several spectroscopic techniques. Furthermore, inhibition of products at all stages of glycation was studied by various assays. Spectroscopic analysis suggests structural perturbations in the HSA macromolecule as a result of modification, which might be due to the generation of free radicals and the formation of AGEs. Inhibition in the formation of glycation has established that quercetin is a better and a more potent antiglycating agent than aminoguanidine at all stages of glycation.

3-Deoxyglucosone: a potential glycating agent accountable for structural alteration in H3 histone protein through generation of different AGEs.

Advanced glycation end-products (AGEs) are heterogeneous group of compounds, known to be implicated in diabetic complications. One of the consequences of the Maillard reaction is attributed to the production of reactive intermediate products such as α-oxoaldehydes. 3-deoxyglucosone (3-DG), an α-oxoaldehyde has been found to be involved in accelerating vascular damage during diabetes. In the present study, calf thymus histone H3 was treated with 3-deoxyglucosone to investigate the generation of AGEs (Nε-carboxymethyllysine, pentosidine), by examining the degree of side chain modifications and formation of different intermediates and employing various physicochemical techniques. The results clearly indicate the formation of AGEs and structural changes upon glycation of H3 by 3-deoxyglucosone, which may hamper the normal functioning of H3 histone, that may compromise the veracity of chromatin structures and function in secondary complications of diabetes.

A clinical correlation of anti-DNA-AGE autoantibodies in type 2 diabetes mellitus with disease duration.

Nonenzymatic glycation of amino groups of DNA bases by reducing sugars can generate advanced glycation end products (AGEs). Cellular formation of AGEs under normal physiology is continuously scanned and removed by efficient system in the cells. However, excess formation and accumulation of AGEs may be cause or consequence of some human diseases. Mammalian DNA incubated with d-glucose for 28 days at 37°C showed structural changes in DNA as confirmed by UV, fluorescence, CD, melting temperature, S1 nuclease sensitivity and gel electrophoresis. Formation of DNA-AGE was confirmed by HPLC and LC-MS. Enzyme immunoassay and electrophoretic mobility shift assay of autoantibodies in type 2 diabetes patients' sera with disease duration of 5-15 years exhibited significantly high binding with DNA-AGE as compared to patients with 1-5 years of disease duration. Autoantibodies against aberrant DNA-AGE may be important in the assessment of initiation/progression of secondary complications in type 2 diabetes mellitus patients.

Biochemical and immunological parameters as indicators of osteoarthritis subjects: role of OH-collagen in auto-antibodies generation.

Osteoarthritis (OA) is characterized by inflammation of the knee joint, which is caused by accumulation of cytokines and C-reactive protein (CRP) in the extracellular matrix as an early immune response to infection. The articular cartilage destruction is discernible by elevated tumour necrosis factor-α (TNF-α). In this study, blood samples of knee osteoarthritis patients were analyzed for biochemical and physiological parameters based on the lipid profile, uric acid, total leukocyte count (TLC), hemoglobin percentage (Hb%) and absolute lymphocyte count (ALC). Furthermore, immunological parameters including TNF-α , interleukin-6 (IL-6) and CRP were analyzed. The presence of antibodies against hydroxyl radical modified collagen-II ((•)OH-collagen-II) was also investigated in arthritis patients using direct binding ELISA. The uric acid and lipid profiles changed extensively. Specifically, increased uric acid levels were associated with OA in both genders, as were enhanced immunological parameters. The TNF-α level also increased in both genders suffering from OA. Finally, auto-antibodies against OH-collagen II antigen were found in the sera of arthritis patients. These results indicated that immunological parameters are better predictors or indexes for diagnosis of OA than biochemical parameters.

Physicochemical analysis of structural alteration and advanced glycation end products generation during glycation of H2A histone by 3-deoxyglucosone.

Advanced glycation end-products comprise a complex and heterogeneous group of compounds that have been implicated in diabetes-related complications. The importance of the Maillard reaction is depicted by the formation of reactive intermediate products known as α-oxoaldehydes, such as 3-deoxyglucosone (3-DG). This product has been found to be involved in accelerated vascular damage in diabetes. In the present study, calf thymus histone H2A was reacted with 3-DG, and the generation of advanced glycation end products was investigated by determining the degree of side chain modifications (lysine and arginine residues), Amadori products, carbonyl content, N(ε) -carboxymethyl lysine, and pentosidine using various physicochemical techniques. Moreover, fluorescence, absorbance as well as structural characteristics of glycated-H2A were comprehensively investigated. Overall, this study demonstrates structural perturbation, formation of different intermediates, and AGEs that are believed to hamper the normal functioning of H2A histone, compromising the integrity of chromatin structures and function in secondary complications of diabetes.

Antiglycating potential of gum arabic capped-silver nanoparticles.

Advanced glycation end products are major contributors to the pathology of diabetes, Alzheimer's disease, and atherosclerosis; accordingly, identification of antiglycation compounds is attracting considerable interest. In the present study, the inhibitory effect of gum arabic capped-silver nanoparticles on advanced glycation end products formation was monitored by several biophysical techniques. Silver nanoparticles were characterized by ultraviolet-visible, high-resolution transmission electron microscopy, and energy-dispersive X-ray spectroscopy. Bovine serum albumin and methylglyoxal mixtures incubated with increasing concentrations of silver nanoparticles showed significant reductions in advanced glycation end product formation that were confirmed by ultraviolet-visible, fluorescence spectrometry, and high-performance liquid chromatography techniques. High-performance liquid chromatography showed decreased adduct formation of glycated protein in the presence of silver nanoparticles. The structural changes induced by silver nanoparticles were further confirmed by circular dichroism and Fourier transform infrared spectroscopy. Strong inhibition of advanced glycation end product formation was observed in the presence of elevated silver nanoparticles. The results of this study suggest that silver nanoparticles are a potent antiglycating agent.

Fine characterization of glucosylated human IgG by biochemical and biophysical methods.

Nonenzymatic glycosylation of proteins finally generates advanced glycation end products (AGEs). The Schiff's base and Amadori adduct are stages of early glycation. AGE-modified IgG may undergo conformational alterations and the final entity of the process may be involved in the pathogenesis of Rheumatoid Arthritis (RA). In this study, glycation of human IgG was carried out with varying concentrations of glucose. Effect of incubation period on glycation of IgG has also been studied. Amadori adduct was detected by nitroblue tetrazolium (NBT) dye. The glucose mediated structural alterations in IgG were studied by UV, fluorescence, CD, FT-IR, DLS and DSC spectroscopy, and SDS-PAGE. Glycation-induced aggregation in AGE-IgG was reported in the form of binding of thioflavin T and congo red. Furthermore, AGE-modified IgG exhibited hyperchromicity, decrease of tryptophan fluorescence accompanied by increase in AGE specific fluorescence, loss of ß-sheet, appearance of new peak in FT-IR, increase in hydrodynamic size and melting temperature. SDS-PAGE results showed decrease in the band intensity of glycosylated-IgG compared to native IgG. Glycation-induced modifications and aggregation of IgG might be important in the pathogenesis of RA.

Physicochemical analysis of structural changes in DNA modified with glucose.

Reactions of reducing sugars with free amino groups of proteins can form advanced glycation end products (AGEs). While the formation of nucleoside AGEs has been studied in detail, no extensive work has been carried out to assess DNA Amadori and DNA advanced glycation end products. In this study, we report biophysical/chemical characterization of glucose-induced changes in DNA, as well as DNA Amadori and DNA advanced glycation end products. Glucose treated DNA exhibited hyperchromicity, decrease in melting temperature, and enhanced emission intensity in a time dependent manner. Formation of DNA Amadori product and DNA advanced glycation end products, mainly CEdG (N²-carboxyethyl-2'-deoxyguanosine), were the major outcome of the study.

Structural and immunological characterization of Amadori-rich human serum albumin: role in diabetes mellitus.

Proteins modifications in diabetes may lead to early glycation products (EGPs) as well as advanced glycation end products (AGEs). Whereas no extensive studies have been carried out to assess the role of EGPs in secondary complications of diabetes, numerous investigators have demonstrated the role of AGEs. Early glycation involves attachment of glucose on ε-NH2 of lysine residues of proteins leading to generation of the Amadori product (an early glycation species). This study reports the structural and immunological characterization of EGPs of HSA because we believe that during persistent hyperglycemia the HSA, one of the major blood proteins, can undergo fast glycation. Glucose mediated generation of EGPs of HSA was quantitated as Amadori products by NBT assay and authenticated by boronate affinity chromatography and LC/MS. Compared to native HSA changes in glycated-HSA were characterized by hyperchromicity, loss in fluorescence intensity and a new peak in the FTIR profile. Immunogenicity of native- and glycated-HSA was evaluated by inducing antibodies in rabbits. Results suggest generation of neo-epitopes on glycated-HSA rendering it highly immunogenic compared to native HSA. Quantization of EGPs of HSA by authentic antibodies against HSA-EGPs can be used as marker for early detection of the initiation/progression of secondary complications of diabetes.

Comparative study of coronary collaterals in diabetic and nondiabetic patients by angiography.

Myocardial ischaemia is known to be significantly related to the development of coronary collaterals, but there are considerable variations in their formation. The nature of this variability is not well understood. Likewise it remains unclear whether diabetes mellitus. DM has any effect on coronary collaterals. The aim of this study was to evaluate the effect of diabetes mellitus on coronary collaterals. This prospective case- control study was done from January to December 2000 in patients undergoing coronary angiography in National Institute of Cardiovascular Diseases (NICVD), Dhaka, who fulfilled the inclusion criteria of having < or = 75% stenosis in at least one coronary artery. The patients with diabetes having CAD without other modifiable major risk factors (hypertension, smoking, dyslipidaemia) were constituted case study group (n=36) and nondiabetic patients having CAD with those risk factors were constituted control group (n=50). Coronary collaterals were graded according to Rentrope scoring system and the collateral score was calculated by summing the Rentrope number of every patient. There was no statistical difference between patients with and without diabetes in clinical characteristics. The mean number of diseased vessel in DM group 2.6+/-0.6 was higher than that in nondiabetic patients (2.1+/-0.8, P>.05). The mean collateral score was 0.5+/-0.6 in DM group and 1.2+/-1.0 in nondiabetic group. These findings suggest that coronary collateral development is significantly poorer in diabetic than on diabetic patients.

High-performance liquid chromatography determination of phenolic constituents in 17 varieties of cowpeas.

Seventeen varieties of cowpeas grown in Arkansas were analyzed for their phenolic constituents using high-performance liquid chromatography (HPLC). Protocatechuic acid was identified as the major phenolic acid present in esterified forms. The amount of protocatechuic acid increased from trace-3.6 to 9.3-92.7 mg/100 g of flour in the 17 varieties of cowpeas after hydrolysis. Six other phenolic acids, including, p-hydroxybenzoic acid, caffeic acid, p-coumaric acid, ferulic acid, 2,4-dimethoxybenzoic acid, and cinnamic acid, were also identified. These phenolic acids were evenly distributed mainly in free acid forms at <7 mg/100 g of flour. Total phenolic contents determined using Folin-Ciocalteu's reagent were largely different among the 17 varieties, ranging from 34.6 to 376.6 mg/100 g of flour. A comparison of the HPLC chromatograms of the 17 cowpea phenolics before and after alkali hydrolysis indicated the conversion of a pattern with evenly distributed peaks to one with a single major peak for protocatechuic acid, suggesting that the chromatograms before hydrolysis better represent the identities of the cowpea varieties.

Temporal association between hospitalization and rate of falls after discharge.

BACKGROUND: Evidence suggests that acute illness and hospitalization may increase the risk for falls. OBJECTIVE: To evaluate the rate of falls, and associated risk factors, for 90 days following hospital discharge. METHODS: We consecutively enrolled 311 patients, aged 65 years and older, discharged from the hospital after an acute medical illness and receiving home-nursing services. Patients were assessed within 5 days of discharge for prehospital and current functioning by self-report, and balance, vision, cognition, and delirium by objective measures. Patients were followed up weekly for 13 weeks for falls, injuries, and health care use. RESULTS: The rate of falls was significantly higher in the first 2 weeks after hospitalization (8.0 per 1000 person-days) compared with 3 months later (1.7 per 1000 person-days) (P =.002). Fall-related injuries accounted for 15% of all hospitalizations in the first month after discharge. Independent prehospital risk factors significantly associated with falls included dependency in activities of daily living, use of a standard walker, 2 or more falls, and more hospitalizations in the year prior. Posthospital risk factors included use of a tertiary amine tricyclic antidepressant, probable delirium, and poorer balance, while use of a cane was protective. CONCLUSIONS: The rate of falls is substantially increased in the first month after medical hospitalization, and is an important cause of injury and morbidity. Posthospital risk factors may be potentially modifiable. Efforts to assess and modify risk factors should be integral to the hospital and posthospital care of older adults (those aged >/=65 years).

Ambulatory ventricular arrhythmias in patients with heart failure do not specifically predict an increased risk of sudden death. PROMISE (Prospective Randomized Milrinone Survival Evaluation) Investigators.

BACKGROUND: Ventricular arrhythmias are a frequent finding in congestive heart failure (CHF) patients and a cause of concern for physicians caring for them. Previous studies have reached conflicting conclusions regarding the importance of ventricular arrhythmias as predictors of sudden death in patients with CHF. This study examined the independent predictive value of ventricular arrhythmias for sudden death and all-cause mortality in PROMISE (Prospective Randomized Milrinone Survival Evaluation). METHODS AND RESULTS: Ventricular arrhythmias were analyzed and quantified by use of prespecified criteria on baseline ambulatory ECGs from 1080 patients with New York Heart Association (NYHA) class III/IV symptoms and a left ventricular ejection fraction