Effects of diet-induced obesity on protein expression in insulin signaling pathways of skeletal muscle in male Wistar rats

BACKGROUND

The prevalence of diet-induced obesity is increasing globally, and posing significant health problems for millions of people worldwide. Diet-induced obesity is a major contributor to the global pandemic of type 2 diabetes mellitus. The reduced ability of muscle tissue to regulate glucose homeostasis plays a major role in the development and prognosis of type 2 diabetes. In this study, an animal model of diet-induced obesity was used to elucidate changes in skeletal muscle insulin signaling in obesity-induced diabetes.

METHODS

Adult male Wistar rats were randomized and assigned to either a control group or to a test group. Controls were fed a standard laboratory pellet diet (chow-fed), while the test group had free access to a highly palatable diet (diet-fed). After 8 weeks, the diet-fed animals were subdivided into three subgroups and their diets were altered as follows: diet-to-chow, diet-fed with addition of fenofibrate given by oral gavage for a further 7 weeks, or diet-fed with vehicle given by oral gavage for a further 7 weeks, respectively.

RESULTS

Untreated diet-fed animals had a significantly higher body weight and metabolic profile than the control chow-fed animals. Intramuscular triacylglyceride levels in the untreated obese animals were significantly higher than those in the control chow-fed group. Expression of protein kinase C beta, phosphatidylinositol 3, Shc, insulin receptor substrate 1, ERK1/2, and endothelial nitric oxide synthase was significantly increased by dietary obesity, while that of insulin receptor beta, insulin receptor substrate 1, and protein kinase B (Akt) were not affected by obesity.

CONCLUSION

These data suggest that diet-induced obesity affects insulin signaling mechanisms, leading to insulin resistance in muscle.

A review of the role of apolipoprotein C-II in lipoprotein metabolism and cardiovascular disease

The focus of this review is on the role of apolipoprotein C-II (apoC-II) in lipoprotein metabolism and the potential effects on the risk of cardiovascular disease (CVD). We searched PubMed/Scopus for articles regarding apoC-II and its role in lipoprotein metabolism and the risk of CVD. Apolipoprotein C-II is a constituent of chylomicrons, very low-density lipoprotein, low-density lipoprotein, and high-density lipoprotein (HDL). Apolipoprotein C-II contains 3 amphipathic α-helices. The lipid-binding domain of apoC-II is located in the N-terminal, whereas the C-terminal helix of apoC-II is responsible for the interaction with lipoprotein lipase (LPL). At intermediate concentrations (approximately 4 mg/dL) and in normolipidemic subjects, apoC-II activates LPL. In contrast, both an excess and a deficiency of apoC-II are associated with reduced LPL activity and hypertriglyceridemia. Furthermore, excess apoC-II has been associated with increased triglyceride-rich particles and alterations in HDL particle distribution, factors that may increase the risk of CVD. However, there is not enough current evidence to clarify whether increased apoC-II causes hypertriglyceridemia or is an epiphenomenon reflecting hypertriglyceridemia. A number of pharmaceutical interventions, including statins, fibrates, ezetimibe, nicotinic acid, and orlistat, have been shown to reduce the increased apoC-II concentrations. An excess of apoC-II is associated with increased triglyceride-rich particles and alterations in HDL particle distribution. However, prospective trials are needed to assess if apoC-II is a CVD marker or a risk factor in high-risk patients.

How dietary patterns could have a role in prevention, progression, or management of diabetes mellitus? Review on the current evidence

OBJECTIVE

To investigate the role of dietary patterns in prevention and management of type 2 diabetes mellitus.

MATERIALS AND METHODS

A systematic review of databases which were published in ISI, Cochrane Central Register of Controlled Trials databases, PubMed, Iran Medex, and MagIran was performed. "Diabetes" and "dietary pattern" were used as the keywords.

RESULTS

A total of 58 studies which aimed to focus on diabetes mellitus, insulin resistance, metabolic syndrome, dietary pattern, and other related key words were reviewed. More than 47,447 articles were found and 46,709 entries of the extracted studies were excluded on the basis of the title and abstracts. The major dietary patterns were: "Healthy", "Western", "Traditional", "Prudent", "Unhealthy", "Mediterranean", "Modern", and "Dietary Approach to Stop Hypertension" (DASH) diets. Comparison of the effects of different diets revealed that dietary patterns containing fiber-rich foods have a protective role in managing diabetes mellitus. "Healthy", "Mediterranean", "Prudent", and "DASH" dietary patterns were associated with lower risk of hyperglycemia.

CONCLUSIONS

The adherence to the Mediterranean, Prudent, or DASH diets could control hyperglycemia. The higher intake of vegetables, fruits, nuts, whole grains, and lower intake of red meat could reduce the risk of type 2 diabetes mellitus.

Periodization of the Early Postnatal Development in the Rat With Particular Attention to the Weaning Period

The early postnatal period is characterized by a great plasticity with critical windows in which any inadequate insult or intervention may be able to influence both positively and adversely postnatal growth and development. After birth the rat littermates enter the presuckling period (initial 6 hours terminated by the first nursing), characterized by transition from the amniotic fluid to the air, by the changes of the ambient temperature, by the termination of placental nutrition and by oxidative stress. After this stage the suckling period initiates and the littermates start to consume milk of their mothers. Comsumption of milk culminates on day 15, then decreases and terminates on postnatal day 28. The end of the suckling period and the onset of physiological weaning is determined by the moment when the youngs for the first time consume the solid food together with milk (postnatal day 17 in rats). On day 19 the first intake of drinking water occurs. The weaning period terminates by the last consumption of maternal milk – on postnatal day 28. It is necessary to stress that the duration of early postnatal periods is independent of the changes of body weight. The precise knowledge of individual ontogenetic periods critical for further development is crucial for the prediction and explanation of reactions to various pathogenetic stimuli both under experimental conditions and in clinical medicine.

Sitagliptin counteracts seasonal fluctuation of glycemic control

AIM: To assess the effect of sitagliptin therapy on seasonal fluctuation of glycemic control in Japanese type 2 diabetic patients.

METHODS: Participating patients (age: 29-80 years) had been treated with conventional oral antidiabetic agents and/or diet and exercise therapy for over 6 mo. From December 2009, 35 patients were additionally prescribed oral sitagliptin starting from 50 mg once daily, while 19 patients taking α-glucosidase inhibitors were switched to sitagliptin. Twenty-four patients who refused sitagliptin formed the control group. Changes of mean monthly hemoglobin A_1c (HbA_1c) during the “winter holiday season” were compared between groups using Student’s t-test (2008-2009 vs 2009-2010). Statistical significance was accepted at P < 0.05. Multivariate analysis was performed to assess whether sitagliptin use was associated with deterioration or improvement of glycemic control.

RESULTS: Both add-on sitagliptin and switching from α-glucosidase inhibitors to sitagliptin prevented the seasonal deterioration of glycemic control and tended to improve HbA_1c. Multivariate analysis revealed that both adding and switching to sitagliptin were negatively correlated with deterioration of glycemic control. In 44 patients who continued sitagliptin therapy for another year, elevation of HbA_1c was suppressed without adverse effects.

CONCLUSION: Sitagliptin is a suitable oral agent for preventing deterioration of glycemic control during the winter holiday season.

Cerium oxide nanoparticles protect cardiac progenitor cells from oxidative stress

Cardiac progenitor cells (CPCs) are a promising autologous source of cells for cardiac regenerative medicine. However, CPC culture in vitro requires the presence of microenvironmental conditions (a complex array of bioactive substance concentration, mechanostructural factors, and physicochemical factors) closely mimicking the natural cell surrounding in vivo, including the capability to uphold reactive oxygen species (ROS) within physiological levels in vitro. Cerium oxide nanoparticles (nanoceria) are redox-active and could represent a potent tool to control the oxidative stress in isolated CPCs. Here, we report that 24 h exposure to 5, 10, and 50 μg/mL of nanoceria did not affect cell growth and function in cardiac progenitor cells, while being able to protect CPCs from H(2)O(2)-induced cytotoxicity for at least 7 days, indicating that nanoceria in an effective antioxidant. Therefore, these findings confirm the great potential of nanoceria for controlling ROS-induced cell damage.

Attenuation of insulin resistance, metabolic syndrome and hepatic oxidative stress by resveratrol in fructose-fed rats

Metabolic syndrome and oxidative stress are common complications of type 2 diabetes mellitus. The present study was designed to determine whether resveratrol, a widely used nutritional supplement, can improve insulin sensitivity, metabolic complication as well as hepatic oxidative stress in fructose-fed rats. Male Sprague Dawley rats (180-200 g) were divided into four groups with 8 animals each. Fructose-fed insulin resistant group (Dia) animals were fed 65% fructose (Research diet, USA) for a period of 8 weeks, whereas control group (Con) animals were fed 65% cornstarch (Research Diet, USA). Resveratrol, 10 mg/kg/day (Dia+Resv) or metformin 300 mg/kg/day (Dia+Met) were administered orally to the 65% fructose-fed rats for 8 weeks. At the end of the feeding schedule, Dia group had insulin resistance along with increased blood glucose, triglyceride, uric acid and nitric oxide (NO) levels. Significant (p<0.05) increase in hepatic TBARS and conjugated dienes, and significant (p<0.05) decrease in hepatic SOD and vitamin C was observed in Dia group compared to Con group. Administration of metformin or resveratrol significantly (p<0.05) normalized all the altered metabolic parameters. However, a marked insulin sensitizing action was only observed in the Dia+Resv group. Similarly, while metformin administration failed to normalize the increased TBARS levels and decreased SOD activity, resveratrol showed a more promising effect of all oxidative stress parameters measured in the present study. Attenuation of hepatic oxidative stress in fructose-fed rat liver after resveratrol administration was associated with significant (p<0.05) increase in nuclear level of NRF2 compared with other groups. The present study demonstrates that resveratrol is more effective than metformin in improving insulin sensitivity, and attenuating metabolic syndrome and hepatic oxidative stress in fructose-fed rats.

A pilot trial assessing urinary gene expression profiling with an mRNA array for diabetic nephropathy

Background

The initiation and progression of diabetic nephropathy (DN) is complex. Quantification of mRNA expression in urinary sediment has emerged as a novel strategy for studying renal diseases. Considering the numerous molecules involved in DN development, a high-throughput platform with parallel detection of multiple mRNAs is needed. In this study, we constructed a self-assembling mRNA array to analyze urinary mRNAs in DN patients with aims to reveal its potential in searching novel biomarkers.

Methods

mRNA array containing 88 genes were fabricated and its performance was evaluated. A pilot study with 9 subjects including 6 DN patients and 3 normal controls were studied with the array. DN patients were assigned into two groups according to their estimate glomerular rate (eGFR): DNI group (eGFR>60 ml/min/1.73 m², n = 3) and DNII group (eGFR<60 ml/min/1.73 m², n = 3). Urinary cell pellet was collected from each study participant. Relative abundance of these target mRNAs from urinary pellet was quantified with the array.

Results

The array we fabricated displayed high sensitivity and specificity. Moreover, the Cts of Positive PCR Controls in our experiments were 24±0.5 which indicated high repeatability of the array. A total of 29 mRNAs were significantly increased in DN patients compared with controls (p<0.05). Among these genes, α-actinin4, CDH2, ACE, FAT1, synaptopodin, COL4α, twist, NOTCH3 mRNA expression were 15-fold higher than those in normal controls. In contrast, urinary TIMP-1 mRNA was significantly decreased in DN patients (p<0.05). It was shown that CTGF, MCP-1, PAI-1, ACE, CDH1, CDH2 mRNA varied significantly among the 3 study groups, and their mRNA levels increased with DN progression (p<0.05).

Conclusion

Our pilot study demonstrated that mRNA array might serve as a high-throughput and sensitive tool for detecting mRNA expression in urinary sediment. Thus, this primary study indicated that mRNA array probably could be a useful tool for searching new biomarkers for DN.

Comorbid Diabetes and Eating Disorders in Adult Patients

Purpose

The lack of research concerning treatment for individuals with diabetes mellitus (DM) and comorbid eating disorders (ED) contributes to the gulf between the psychosocial needs of individuals with the two conditions and the treatment they receive. Empirical evidence has established that the prognosis of patients with this comorbid diagnosis (ED-DM) is poor in the absence of a specialized DM treatment specifically adapted to ED. In individuals with DM, comorbid ED is associated with numerous complications. Despite these interactions, current knowledge about the comorbid diagnosis is limited, and eating disorders in patients with diabetes often remain undiagnosed. This article presents standard procedures for assessment and optimal therapeutic interventions for patients with ED and DM.

Conclusion

In patients with diabetes, problematic eating behaviors and symptoms should be assessed routinely. When an eating disorder is detected, diabetes management needs to be adapted, binge eating or medication misuse needs to be addressed, and eating disorder specialists should be included in the multidisciplinary team.

Fetal programming of body composition, obesity, and metabolic function: the role of intrauterine stress and stress biology

Epidemiological, clinical, physiological, cellular, and molecular evidence suggests that the origins of obesity and metabolic dysfunction can be traced back to intrauterine life and supports an important role for maternal nutrition prior to and during gestation in fetal programming. The elucidation of underlying mechanisms is an area of interest and intense investigation. In this perspectives paper we propose that in addition to maternal nutrition-related processes it may be important to concurrently consider the potential role of intrauterine stress and stress biology. We frame our arguments in the larger context of an evolutionary-developmental perspective that supports roles for both nutrition and stress as key environmental conditions driving natural selection and developmental plasticity. We suggest that intrauterine stress exposure may interact with the nutritional milieu, and that stress biology may represent an underlying mechanism mediating the effects of diverse intrauterine perturbations, including but not limited to maternal nutritional insults (undernutrition and overnutrition), on brain and peripheral targets of programming of body composition, energy balance homeostasis, and metabolic function. We discuss putative maternal-placental-fetal endocrine and immune/inflammatory candidate mechanisms that may underlie the long-term effects of intrauterine stress. We conclude with a commentary of the implications for future research and clinical practice.

The Role of Endocrine Disruptors in the Epigenetics of Reproductive Disease and Dysfunction: Potential Relevance to Humans

In a murine model, we have linked early life toxicant exposure to reduced uterine sensitivity to progesterone, a phenotype we had previously associated with inflammation in endometriosis patients. Subsequent studies revealed that developmental toxicant exposure not only reduces fertility in male and female mice but also negatively impacts pregnancy leading to spontaneous preterm birth (PTB). An epigenetic alteration of the progesterone receptor gene correlated with reduced fertility and adverse pregnancy outcomes and persisted in multiple generations of mice in the absence of an additional toxicant exposure. Gene-environment interactions in women may explain why some patients "at risk" for PTB deliver at term while others without known risks deliver early. Our model provides a unique system to unravel the interactive influences of inflammation and reduced progesterone responsiveness on PTB and suggests that therapy needs to begin prior to pregnancy (and involve both partners) rather than once the inflammatory cascade has been initiated.

A fully human, allosteric monoclonal antibody that activates the insulin receptor and improves glycemic control

Many patients with diabetes mellitus (both type 1 and type 2) require therapy to maintain normal fasting glucose levels. To develop a novel treatment for these individuals, we used phage display technology to target the insulin receptor (INSR) complexed with insulin and identified a high affinity, allosteric, human monoclonal antibody, XMetA, which mimicked the glucoregulatory, but not the mitogenic, actions of insulin. Biophysical studies with cultured cells expressing human INSR demonstrated that XMetA acted allosterically and did not compete with insulin for binding to its receptor. XMetA was found to function as a specific partial agonist of INSR, eliciting tyrosine phosphorylation of INSR but not the IGF-IR. Although this antibody activated metabolic signaling, leading to enhanced glucose uptake, it neither activated Erk nor induced proliferation of cancer cells. In an insulin resistant, insulinopenic model of diabetes, XMetA markedly reduced elevated fasting blood glucose and normalized glucose tolerance. After 6 weeks, significant improvements in HbA(1c), dyslipidemia, and other manifestations of diabetes were observed. It is noteworthy that hypoglycemia and weight gain were not observed during these studies. These studies indicate, therefore, that allosteric monoclonal antibodies have the potential to be novel, ultra-long acting, agents for the regulation of hyperglycemia in diabetes.

Upregulation of proinflammatory cytokine production in response to bacterial pathogen-associated molecular patterns in dogs with diabetes mellitus undergoing insulin therapy

BACKGROUND

Metabolic alterations associated with diabetes mellitus alter innate immunity. Dogs often develop infectious or inflammatory complications related to diabetes mellitus, yet little is known about the effects of diabetes mellitus on the immune system in this species.

METHODS

Prospective evaluation in dogs with poorly regulated spontaneous type 1 diabetes mellitus (T1DM). In vitro leukocyte cytokine response to lipopolysaccharide (LPS), lipoteichoic acid (LTA), and peptidoglycan (PG) was compared between dogs with T1DM and healthy dogs. Additionally, the effect of acute in vitro glucose exposure on leukocyte tumor necrosis factor (TNF) production from healthy dogs was measured.

RESULTS

Leukocytes from dogs with T1DM had significantly greater TNF production after LTA and PG stimulation compared with leukocytes from healthy dogs. Leukocyte interleukin (IL)-6 production was greater after stimulation with LPS, LTA, PG, and phosphate-buffered saline in the T1DM group. No such difference was noted when evaluating IL-10 production between groups regardless of stimulant. Dogs with T1DM had significantly greater IL-6 to IL-10 production ratios than healthy dogs. Acute exposure to dextrose did not augment cytokine production from healthy canine leukocytes.

CONCLUSIONS

Dogs with T1DM have altered innate immunity characterized by upregulation of proinflammatory cytokine production without a concurrent change in anti-inflammatory cytokine production. This may be one explanation for the common infectious and inflammatory complications associated with T1DM in dogs.

Defining the role of bariatric surgery in polycystic ovarian syndrome patients

Polycystic ovarian syndrome (PCOS) is the most common endocrine disorder in women. To meet PCOS criteria, women must have a combination of hyperandrogenism, anovulation and ultrasound findings. Almost 10% of all reproductive age women worldwide show signs of PCOS. Although women often seek care for gynecological or body image concerns, many PCOS women are at risk for metabolic syndrome (MS). Many of the metabolic consequences are overlooked and undertreated by physicians because these patients tend to be young, reproductive age women. MS and obesity coexist commonly with PCOS. These young women are predisposed to glucose abnormalities and ultimately diabetes mellitus, dyslipidemia and eventually cardiovascular disease. Bariatric surgery can be an effective means of weight loss in PCOS women. Surgical techniques have become safer and less invasive over time and have been found to be effective in achieving significant weight loss. Surgical options have also increased, giving patients more choices. Bariatric surgery may prevent or reverse metabolic syndrome. Bariatric surgery may also have reproductive benefits in PCOS patients. Although bariatric surgery has historically been performed in older, reproductive aged women, it has recently gained favor in adolescents as well. This is of particular importance due to the prevalence of both PCOS and MS in adolescents. Treatment of PCOS and MS certainly requires a combination of medical therapy, psychological support and lifestyle modifications. These treatments are difficult and often frustrating for patients and physicians. Bariatric surgery can be effective in achieving significant weight loss, restoration of the hypothalamic pituitary axis, reduction of cardiovascular risk and even in improving pregnancy outcomes. Ultimately, bariatric surgery should be considered part of the treatment in PCOS women, especially in those with MS.

[In utero fetal programming and its impact on health in adulthood]

Adverse events during intrauterine life may program organ growth and favor disease later in life. This is the usually called 'Barker's hypothesis'. Increasing evidence suggests that conditions like vascular disease, hypertension, metabolic syndrome, and type 2 diabetes mellitus are programmed during the early stages of fetal development and become manifest in late stages of life, when there is an added impact of lifestyle and other conventional acquired environmental risk factors that interact with genetic factors. The aim of this review was to provide additional, updated evidence to support the association between intrauterine fetal health and increased prevalence of chronic non-communicable diseases in adulthood. Various potential cellular and molecular mechanisms proposed to be related to the above hypothesis are discussed, including endothelial function, oxidative stress, insulin resistance, and mitochondrial function.

Improvement of isolated rat pancreatic islets function by combination of cerium oxide nanoparticles/sodium selenite through reduction of oxidative stress

Insulin Dependent Diabetes Mellitus (IDDM) is a disease with high incidence with no pure cure therapy yet. In most of cases, these patients need pancreatic islets transplantation that is not completely successful because of oxidative stress happening during isolation and transplantation procedures. In the present study, effective factors in transplantation procedure such as viability, insulin secretion, production of reactive oxygen molecules (ROM), and mitochondrial energy as ATP/ADP ratio were examined in the isolated islets exposed to sodium selenite (Na₂SeO₃; 0 30 nmol/L), metal form of cerium oxide (100 nm), cerium oxide nanoparticles (100 nm) and combination of Na₂SeO₃ (30 nmol/L)/cerium oxide nanoparticles (100 nm) in a time course (1, 2, 4 and 6 days posttreatment) manner. The results showed a significant increase of cells viability, secretion of insulin, and ATP/ADP ratio and a reduction in ROM by use of sodium selenite, cerium oxide nanoparticles, and especially combination of cerium oxide nanoparticles/sodium selenite. Interestingly, not only no improvement was found with metal form of cerium oxide but also deterioration occurred in tested markers. Results suggest that pretreatment with combination of cerium oxide nanoparticles/sodium selenite can improve transplantation outcome and graft function by control of oxidative stress damage.

Targeting tumor necrosis factor alpha (TNF-α) in diabetic rats could approve avenues for an efficient strategy for diabetic therapy

BACKGROUND

Several studies held belief that downregulation of TNF-α may be effective for preventing diabetes and it's complications. However, it is not known whether TNF-α downregulation in long-term can generate any biological adverse.

AIM

The aim of the present study was to clarify what the impact is for such treatment with specific antibody for TNF-α on the other biological activities after 4weeks.

METHODS

Using western blot, IHC, Elisa, biochemical assays and scanning electron microscope.

RESULTS

Results show that TNF-α, FOXO-1, IL-6 and MPO, when expressed in diabetic rats, collectively induce dramatic changes in diabetic rats. Since, TNF-α is involved in activation of transcription factor FOXO1 along with oxidative stress mediated by neutrophils. On one hand, IL-6 mediates neutrophils activation leading to an augmentation in stress mediators. And FOXO1 is activated in order to eliminate these oxidative mediators, on the other hand. Data show also that the prominent defect in mucosal IgA and IL-2 secretions may be the leading reasons for digestive atrophy. Finally, Akt-1 inhibits the cleavage of caspase 3, so, it could prevent the incidence of apoptosis.

CONCLUSION

Findings of this study reveal how TNF-α can be mechanistically coupled to greater diabetic complications potential.

Omentin-1 exerts bone-sparing effect in ovariectomized mice

Omentin-1 inhibited osteoblast differentiation in vitro. In co-culture systems of osteoblasts and osteoclast precursors, omentin-1 reduced osteoclast formation by stimulating osteoprotegerin (OPG) and inhibiting receptor activator for nuclear factor κB ligand (RANKL) production in osteoblasts. In vivo, adenovirus-mediated overexpression of omentin-1 suppressed bone turnover and restored bone mineral density (BMD) and bone strength in ovariectomized mice.

INTRODUCTION

Omentin-1 (also intelectin-1) is a recently identified visceral adipose tissue-derived cytokine that is highly abundant in plasma. This study was undertaken to investigate the effects of omentin-1 on bone metabolism.

METHODS

Osteoblast differentiation was assessed by measuring alkaline phosphatase activity, osteocalcin production and matrix mineralization. OPG and RANKL protein expression and secretion in osteoblasts were detected by Western blot and ELISA, respectively. The effect of recombinant omentin-1 on osteoclast formation was examined in co-culture systems of osteoblasts and osteoclast precursors. The effects of intravenous administration of adenoviral-delivered omentin-1 on bone mass, bone strength, and bone turnover were also examined in ovariectomized mice.

RESULTS

In vitro, omentin-1 inhibited osteoblast differentiation, while it had no direct effect on osteoclast differentiation; it also reduced osteoclast formation in the co-culture systems through stimulating OPG and inhibiting RANKL production in osteoblasts. In vivo, adenovirus-mediated overexpression of omentin-1 partially restored BMD and bone strength in ovariectomized mice, accompanied by decreased levels of plasma osteocalcin and tartrate-resistant acid phosphatase-5b and lower serum RANKL/OPG ratios.

CONCLUSION

The present study suggests that omentin-1 ameliorates bone loss induced by estrogen deficiency via downregulating the RANKL/OPG ratio.

Adipokines and central control in adenosine A1 receptor dependent glucose metabolism

Adenosine A1 receptor-deficient mice develop a phenotype of insulin resistance and grow fat. Participating pathophysiological pathways are not understood in detail yet, as discussed in our recent manuscript. This commentary further explores possible pathophysiological mechanisms with emphasis on the roles of the adipokines resistin, retinol-binding protein 4, adiponectin and the function of the gastric hormone ghrelin in adenosine mediated central regulation of energy balance. The postulate of an important function of ghrelin/A1AR axis provides a good hypothetical basis for further investigations to clarify the mechanism of A1AR-dependent metabolic homeostasis.

Dipeptidyl peptidase-4 inhibitors: 3 years of experience

According to the latest American Diabetes Association guidelines, lowering glycated hemoglobin (HbA(1c)) to below or around 7% has been shown to reduce microvascular and neuropathic complications of diabetes and, if implemented soon after the diagnosis of diabetes, is associated with long-term reduction in macrovascular disease. Recently a new class of antidiabetes drugs has been developed, dipeptidyl peptidase-4 (DPP-4) inhibitors, which act by inhibiting DPP-4, the enzyme that inactivates glucagon-like peptide-1 (GLP-1). Through the inhibition of DPP-4, DPP-4 inhibitors enhance the effects of GLP-1 and glucose-dependent insulinotropic peptide, increasing glucose-mediated insulin secretion and suppressing glucagon secretion. We conducted a review analyzing clinical efficacy and safety of DPP-4 inhibitors, both alone and in combination with other antidiabetes drugs, including randomized controlled trials about sitagliptin, vildagliptin, saxagliptin, and linagliptin conducted in the latest 15 years. We concluded that, once metformin fails to maintain glycemic control, addition of DPP-4 inhibitors should be the logical choice: they seems to lower HbA(1c) levels by 0.6-0.9 percentage points and to have a comparable effect on HbA(1c) versus the addition of a sulfonylurea or glitazone. They also have positive effects on β-cell function, and they have neutral effects on body weight. Furthermore, DPP-4 inhibitors prevent the risk of hypoglycemia posed by sulfonylureas.

Jueming Prescription reduces body weight by increasing the mRNA expressions of beta3-adrenergic receptor and uncoupling protein-2 in adipose tissue of diet-induced obese rats

OBJECTIVE

To investigate the antiobesity effect of Jueming Prescription (JMP), a Chinese herbal medicine formula, and its influence on mRNA expressions of beta3 adrenergic receptor (beta3-AR) and uncoupling protein-2 (UCP-2) in adipose tissue of diet-induced obese rats.

METHODS

Fifty male Sprague-Dawley rats were randomly divided into the normal control group (n =8) that was on a standard chow diet, and the obese model group (n =42) that was on a diet of high fat chow. Two weeks after the high fat diet, 29 obese rats in the obese model group were further randomly divided into 3 groups: the untreated obese model group (n =9), the metformin group (n =10, metformin 300 mg kg⁻¹ day)⁻¹, and the JMP group (n =10, JMP 4 g kg⁻¹ day⁻¹). After 8-week treatment, body weight, wet weight of visceral fat, and percentage of body fat (PBF) were measured. The levels of fasting blood glucose, serum lipids, and insulin were assessed, and insulin sensitivity index (ISI) was calculated. The adipose tissue section was stained with hematoxylin-Eosin, and the cellular diameter and quantity of adipocytes were evaluated by light microscopy. The mRNA expressions of beta3-AR and UCP-2 from the peri-renal fat tissue were determined by real-time reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

Compared with the obese model group, treatment with JMP resulted in significantly lower body weight, wet weight of visceral fat, PBF, and diameter of adipocytes, and significantly higher level of high-density lipoprotein cholesterol, ISI (all P<0.01), JMP increased the mRNA expressions of beta3-AR and UCP-2 from perirenal fat tissue (P <0.05, P<0.01).

CONCLUSIONS

JMP could reduce body weight and adipocyte size; and the effect was associated with the up-regulation of beta3-AR and UCP-2 expressions in the adipose tissue and improvement of insulin sensitivity.

Leucine signaling in the pathogenesis of type 2 diabetes and obesity

Epidemiological evidence points to increased dairy and meat consumption, staples of the Western diet, as major risk factors for the development of type 2 diabetes (T2D). This paper presents a new concept and comprehensive review of leucine-mediated cell signaling explaining the pathogenesis of T2D and obesity by leucine-induced over-stimulation of mammalian target of rapamycin complex 1 (mTORC1). mTORC1, a pivotal nutrient-sensitive kinase, promotes growth and cell proliferation in response to glucose, energy, growth factors and amino acids. Dairy proteins and meat stimulate insulin/insulin-like growth factor 1 signaling and provide high amounts of leucine, a primary and independent stimulator for mTORC1 activation. The downstream target of mTORC1, the kinase S6K1, induces insulin resistance by phosphorylation of insulin receptor substrate-1, thereby increasing the metabolic burden of β-cells. Moreover, leucine-mediated mTORC1-S6K1-signaling plays an important role in adipogenesis, thus increasing the risk of obesity-mediated insulin resistance. High consumption of leucine-rich proteins explains exaggerated mTORC1-dependent insulin secretion, increased β-cell growth and β-cell proliferation promoting an early onset of replicative β-cell senescence with subsequent β-cell apoptosis. Disturbances of β-cell mass regulation with increased β-cell proliferation and apoptosis as well as insulin resistance are hallmarks of T2D, which are all associated with hyperactivation of mTORC1. In contrast, the anti-diabetic drug metformin antagonizes leucine-mediated mTORC1 signaling. Plant-derived polyphenols and flavonoids are identified as natural inhibitors of mTORC1 and exert anti-diabetic and anti-obesity effects. Furthermore, bariatric surgery in obesity reduces increased plasma levels of leucine and other branched-chain amino acids. Attenuation of leucine-mediated mTORC1 signaling by defining appropriate upper limits of the daily intake of leucine-rich animal and dairy proteins may offer a great chance for the prevention of T2D and obesity, as well as other epidemic diseases of civilization with increased mTORC1 signaling, especially cancer and neurodegenerative diseases, which are frequently associated with T2D.

Improved diabetes control and pancreatic function in a type 2 diabetic after omeprazole administration

A 43-year-old man with type 2 diabetes, opposed to insulin use and poorly responsive to oral agents added sequentially over 6 years, was placed on 40 mg omeprazole twice daily. A linear decline in daily fasting blood glucose was observed over the first two-month treatment, and his hemoglobin A1c was reduced from 11.9% to 8.2%, then sustained at 8.1% after four months. Glucose, insulin, and C-peptide response to a 2-hour glucose tolerance test were consistently improved across this time period, and calculated beta-cell mass increased by 67%. We believe these responses are consistent with activation or neogenesis of pancreatic beta cells, possibly through a gastrin-mediated mechanism.

Protective effect of yacon leaves decoction against early nephropathy in experimental diabetic rats

Nephropathy is the most common cause of morbidity and mortality in diabetic patients. Prevention of this complication has a major relevance. Smallanthus sonchifolius (yacon) leaves have been shown to ameliorate hyperglycemia in streptozotocin-induced diabetic rats. We examined the beneficial effects of yacon leaves decoction on diabetic nephropathy and explored the possible underlying action mechanism. Streptozotocin-diabetic rats were orally administered 10% yacon leaves water decoction (70mg dry extract/kg body weight) once a day for 4weeks. Biochemical parameters in blood and urine were analyzed and immunohistochemistry staining, western immunoblotting and qRT-PCR were assessed. Yacon decoction significantly decreased high blood glucose level in diabetic rats and improved insulin production. Diabetic-dependent alterations in urinary albumin excretion, creatinine clearance, kidney hypertrophy and basement membrane thickening were attenuated by yacon decoction. These findings were associated with a marked decrease in TGF-β1/Smad2/3 signaling. The expression of molecular markers of diabetic nephropathy such as collagen IV, laminin-1, fibronectin and collagen III were also diminished in the yacon-treated group compared to control diabetic group. These results suggest that yacon leaves decoction is a protective agent against renal damage in diabetic nephropathy, whose action can be mediated by TGF-β/Smads signals.

Cytochrome P-450 CYP2E1 knockout mice are protected against high-fat diet-induced obesity and insulin resistance

Conventional (whole body) CYP2E1 knockout mice displayed protection against high-fat diet-induced weight gain, obesity, and hyperlipidemia with increased energy expenditure despite normal food intake and spontaneous locomotor activity. In addition, the CYP2E1 knockout mice displayed a marked improvement in glucose tolerance on both normal chow and high-fat diets. Euglycemic-hyperinsulinemic clamps demonstrated a marked protection against high-fat diet-induced insulin resistance in CYP2E1 knockout mice, with enhanced adipose tissue glucose uptake and insulin suppression of hepatic glucose output. In parallel, adipose tissue was protected against high-fat diet-induced proinflammatory cytokine production. Taken together, these data demonstrate that the CYP2E1 deletion protects mice against high-fat diet-induced insulin resistance with improved glucose homeostasis in vivo.

Pathobiochemical changes in diabetic skeletal muscle as revealed by mass-spectrometry-based proteomics

Insulin resistance in skeletal muscle tissues and diabetes-related muscle weakness are serious pathophysiological problems of increasing medical importance. In order to determine global changes in the protein complement of contractile tissues due to diabetes mellitus, mass-spectrometry-based proteomics has been applied to the investigation of diabetic muscle. This review summarizes the findings from recent proteomic surveys of muscle preparations from patients and established animal models of type 2 diabetes. The potential impact of novel biomarkers of diabetes, such as metabolic enzymes and molecular chaperones, is critically examined. Disease-specific signature molecules may be useful for increasing our understanding of the molecular and cellular mechanisms of insulin resistance and possibly identify new therapeutic options that counteract diabetic abnormalities in peripheral organ systems. Importantly, the biomedical establishment of biomarkers promises to accelerate the development of improved diagnostic procedures for characterizing individual stages of diabetic disease progression, including the early detection of prediabetic complications.

Glucose: a vital toxin and potential utility of melatonin in protecting against the diabetic state

The molecular mechanisms including elevated oxidative and nitrosative reactants, activation of pro-inflammatory transcription factors and subsequent inflammation appear as a unified pathway leading to metabolic deterioration resulting from hyperglycemia, dyslipidemia, and insulin resistance. Consistent evidence reveals that chronically-elevated blood glucose initiates a harmful series of processes in which toxic reactive species play crucial roles. As a consequence, the resulting nitro-oxidative stress harms virtually all biomolecules including lipids, proteins and DNA leading to severely compromised metabolic activity. Melatonin is a multifunctional indoleamine which counteracts several pathophysiologic steps and displays significant beneficial effects against hyperglycemia-induced cellular toxicity. Melatonin has the capability of scavenging both oxygen and nitrogen-based reactants and blocking transcriptional factors which induce pro-inflammatory cytokines. These functions contribute to melatonin's antioxidative, anti-inflammatory and possibly epigenetic regulatory properties. Additionally, melatonin restores adipocyte glucose transporter-4 loss and eases the effects of insulin resistance associated with the type 2 diabetic state and may also assist in the regulation of body weight in these patients. Current knowledge suggests the clinical use of this non-toxic indoleamine in conjunction with other treatments for inhibition of the negative consequences of hyperglycemia for reducing insulin resistance and for regulating the diabetic state.

How safe is the use of herbal weight-loss products sold over the internet?

BACKGROUND

In recent years, the use of herbal weight-loss products sold over the Internet has rapidly increased; however, the safety of these products has not been well documented yet. More importantly, the declared ingredients in these products could be different than the marketed contents.

METHODS

Nine different herbal weight-loss products sold over the Internet were obtained. The ingredients of each product were analyzed in the Laboratory of Forensic Medicine and the Scientific and Technological Research Laboratory of Inonu University.

RESULTS

Although all studied weight-loss products were presented as pure herbal, three of them contain sibutramine, three contain caffeine, and three contain caffeine + temazepam. The amount of sibutramine in each capsule was found to be over 10 mg. We analyzed toxic and trace element levels of nine herbal products and found that these herbal products, even in low amounts, contain Pb, Al, Ni, and Ba.

CONCLUSIONS

Our results indicate that herbal weight-loss products available without prescription and claimed to be purely herbal may contain pharmaceutical substances like sibutramine or temazepam in high doses. Moreover, they also may become contaminated with toxic metals. Since people commonly use these products unaware of its real constituents and without the suggestion or control of a physician, they might cause various health problems some of which might be harmful. Strict legal rules and control mechanisms must be established to minimize their possible harmful effects.

Rosuvastatin and atorvastatin: comparative effects on glucose metabolism in non-diabetic patients with dyslipidaemia

The ever increasing interventional CVD outcome studies have resulted in statins being an essential factor of cardiovascular prevention strategies. The JUPITER study in 2008, despite reducing CVD and overall mortality, highlighted an increase in new onset diabetes in the rosuvastatin treated arm. Since then there have been many meta-analyses of the RCTs and the largest carried out by Sattar et al showed a significant increase in the incidence of diabetes during the trials. The findings from the individual studies when comparing the different statins were less clear. A higher statin dosage and risk factors associated with diabetes appeared to predict this phenomenon. There have been many studies investigating the effects of statins on glycaemic control, but again no clear conclusion is apparent. Despite the increase in new onset diabetes observed, the risk is clearly out-weighed by the CVD benefits observed in nearly all the statin trials. Thus, no change is required to any of the prevention guidelines regarding statins. However, it may be prudent to monitor glycaemic control after commencing statin therapy. This review will focus on atorvastatin which is the most widely used statin worldwide and rosuvastatin which is the most efficacious. This will be against a background of the effects of other statins on glucose metabolism in non-diabetic patients.

Beneficial effects of long-term administration of an oral formulation of Angiotensin-(1-7) in infarcted rats

In this study was evaluated the chronic cardiac effects of a formulation developed by including angiotensin(Ang)-(1-7) in hydroxypropyl β-cyclodextrin (HPβCD), in infarcted rats. Myocardial infarction (MI) was induced by left coronary artery occlusion. HPβCD/Ang-(1-7) was administered for 60 days (76 μg/Kg/once a day/gavage) starting immediately before infarction. Echocardiography was utilized to evaluate usual cardiac parameters, and radial strain method was used to analyze the velocity and displacement of myocardial fibers at initial time and 15, 30, and 50 days after surgery. Real-time PCR was utilized to evaluate the fibrotic signaling involved in the remodeling process. Once-a-day oral HPβCD/Ang-(1-7) administration improved the cardiac function and reduced the deleterious effects induced by MI on TGF-β and collagen type I expression, as well as on the velocity and displacement of myocardial fibers. These findings confirm cardioprotective effects of Ang-(1-7) and indicate HPβCD/Ang-(1-7) as a feasible formulation for long-term oral administration of this heptapeptide.

Resistance Training in Type II Diabetes Mellitus: Impact on Areas of Metabolic Dysfunction in Skeletal Muscle and Potential Impact on Bone

The prevalence of Type II Diabetes mellitus (T2DM) is increasing rapidly and will continue to be a major healthcare expenditure burden. As such, identification of effective lifestyle treatments is paramount. Skeletal muscle and bone display metabolic and functional disruption in T2DM. Skeletal muscle in T2DM is characterized by insulin resistance, impaired glycogen synthesis, impairments in mitochondria, and lipid accumulation. Bone quality in T2DM is decreased, potentially due to the effects of advanced glycation endproducts on collagen, impaired osteoblast activity, and lipid accumulation. Although exercise is widely recognized as an important component of treatment for T2DM, the focus has largely been on aerobic exercise. Emerging research suggests that resistance training (strength training) may impose potent and unique benefits in T2DM. The purpose of this review is to examine the role of resistance training in treating the dysfunction in skeletal muscle and the potential role for resistance training in treating the associated dysfunction in bone.

The possible role of ribosomal protein S6 kinase 4 in the senescence of endothelial progenitor cells in diabetes mellitus

Background

The decrease and dysfunction of endothelial progenitor cells (EPCs) has been assumed as an important cause/consequence of diabetes mellitus (DM) and its complications, in which the senescence of EPCs induced by hyperglycemia may play an immensurable role. However, the mechanisms of EPCs senescence has not been fully investigated. Recently, ribosomal protein S6 kinase 4 (RSK4), a member of serine/threomine (Ser/Thr) kinase family and p53-related gene, is reported to regulate the replicative and stress-induced senescence of different cells.

Presentation of the hypothesis

These above lead to consideration of an evidence-based hypothesis that RSK4 may serve as a mediator of EPCs senescence in DM.

Testing the hypothesis

EPCs of healthy subjects and DM patients are isolated from peripheral blood and incubated with high glucose (HG). Then, the EPCs senescence would be detected by senescence associated β-galactosides (SA-β-gal) staining. Meanwhile, the RSK4 expression is assessed by RT-PCR and western blot. Moreover, overexpressing or RNA interfering of RSK4 in EPCs to investigate the relationship between RSK4 expression and the senescence of EPCs are necessary to substantiate this hypothesis. Also, studies on possible upstream and downstream factors of RSK4 would be explored to reveal the RSK4-mediated senescence pathway in EPCs.

Implications of the hypothesis

If proved, this hypothesis will provide another mediator of EPCs senescence, and may establish a novel pathogenesis for DM and further benefit to the management of DM.

Xanthigen suppresses preadipocyte differentiation and adipogenesis through down-regulation of PPARγ and C/EBPs and modulation of SIRT-1, AMPK, and FoxO pathways

Xanthigen is a source of punicic acid and fucoxanthin derived from pomegranate seed and brown seaweed, respectively with recognized triacylglycerol-lowering effects in humans, yet the mechanism remains to be fully elucidated. The present study investigated the inhibitory effects of Xanthigen, fucoxanthin, and punicic acid (70% in pomegranate seed oil) on the differentiation of 3T3-L1 preadipocytes. Xanthigen potently and dose-dependently suppressed accumulation of lipid droplets in adipocytes compared to its individual components, fucoxanthin and pomegranate seed oil. Western blot analysis revealed that Xanthigen markedly down-regulated the protein levels of key adipogenesis transcription factors peroxisome proliferator-activated receptor (PPAR)γ, CCAAT/enhancer binding protein (C/EBP) β, and C/EBPδ as well as a key enzyme involved in adipogenesis, fatty acid synthase (FAS). Xanthigen up-regulated the NAD(+)-dependent histone deacetylases (SIRT1) and activated AMP-activated protein kinase (AMPK) signaling in differentiated 3T3-L1 adipocytes. In addition, Xanthigen may also stimulate insulin trigger signaling and result in Akt-dependent phosphorylation of forkhead/winged helix O (FoxO)1 and FoxO3a. These results indicate that Xanthigen suppresses adipocyte differentiation and lipid accumulation through multiple mechanisms and may have applications for the treatment of obesity.

Mammalian foetal ovarian development: consequences for health and disease

The development of a normal ovary during foetal life is essential for the production and ovulation of a high-quality oocyte in adult life. Early in embryogenesis, the primordial germ cells (PGCs) migrate to and colonise the genital ridges. Once the PGCs reach the bipotential gonad, the absence of the sex-determining region on the Y chromosome (SRY) gene and the presence of female-specific genes ensure that the indifferent gonad takes the female pathway and an ovary forms. PGCs enter into meiosis, transform into oogonia and ultimately give rise to oocytes that are later surrounded by granulosa cells to form primordial follicles. Various genes and signals are implicated in germ and somatic cell development, leading to successful follicle formation and normal ovarian development. This review focuses on the differentiation events, cellular processes and molecular mechanisms essential for foetal ovarian development in the mice and humans. A better understanding of these early cellular and morphological events will facilitate further study into the regulation of oocyte development, manifestation of ovarian disease and basis of female infertility.

Trace glucose and lipid metabolism in high androgen and high-fat diet induced polycystic ovary syndrome rats

BACKGROUND

There is a high prevalence of diabetes mellitus (DM) and dyslipidemia in women with polycystic ovary syndrome (PCOS). The purpose of this study was to investigate the role of different metabolic pathways in the development of diabetes mellitus in high-androgen female mice fed with a high-fat diet.

METHODS

Female Sprague-Dawley rats were divided into 3 groups: the control group(C), n = 10; the andronate-treated group (Andronate), n = 10 (treated with andronate, 1 mg/100 g body weight/day for 8 weeks); and the andronate-treated and high-fat diet group (Andronate+HFD), n = 10. The rate of glucose appearance (Ra of glucose), gluconeogenesis (GNG), and the rate of glycerol appearance (Ra of glycerol) were assessed with a stable isotope tracer. The serum sex hormone levels, insulin levels, glucose concentration, and the lipid profile were also measured.

RESULTS

Compared with control group, both andronate-treated groups exhibited obesity with higher insulin concentrations (P < 0.05) but similar blood glucose concentrations. Of the two andronate-treated groups, the andronate+HFD group had the most serious insulin resistance (IR). Estrus cycles were completely acyclic, with polycystic ovaries and elevated serum lipid profiles in the andronate+HFD group (P < 0.05). Ra of glucose and GNG increased significantly in the andronate+HFD rats. However, the Ra of glycerol was similar in the three groups.

CONCLUSIONS

Andronate with HFD rat model showed ovarian and metabolic features of PCOS, significant increase in glucose Ra, GNG, and lipid profiles, as well as normal blood glucose levels. Therefore, aberrant IR, increased glucose Ra, GNG, and lipid metabolism may represent the early-stage of glucose and lipid kinetics disorder, thereby might be used as potential early-stage treatment targets for PCOS.

Nonesterified fatty acid determination for functional lipidomics: comprehensive ultrahigh performance liquid chromatography-tandem mass spectrometry quantitation, qualification, and parameter prediction

Despite their central importance for lipid metabolism, straightforward quantitative methods for determination of nonesterified fatty acid (NEFA) species are still missing. The protocol presented here provides unbiased quantitation of plasma NEFA species by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Simple deproteination of plasma in organic solvent solution yields high accuracy, including both the unbound and initially protein-bound fractions, while avoiding interferences from hydrolysis of esterified fatty acids from other lipid classes. Sample preparation is fast and nonexpensive, hence well suited for automation and high-throughput applications. Separation of isotopologic NEFA is achieved using ultrahigh-performance liquid chromatography (UPLC) coupled to triple quadrupole LC-MS/MS detection. In combination with automated liquid handling, total assay time per sample is less than 15 min. The analytical spectrum extends beyond readily available NEFA standard compounds by a regression model predicting all the relevant analytical parameters (retention time, ion path settings, and response factor) of NEFA species based on chain length and number of double bonds. Detection of 50 NEFA species and accurate quantification of 36 NEFA species in human plasma is described, the highest numbers ever reported for a LC-MS application. Accuracy and precision are within widely accepted limits. The use of qualifier ions supports unequivocal analyte verification.

Proteomic characterization of adipose tissue constituents, a necessary step for understanding adipose tissue complexity

The original concept of adipose tissue as an inert storage depot for the excess of energy has evolved over the last years and it is now considered as one of the most important organs regulating body homeostasis. This conceptual change has been supported by the demonstration that adipose tissue serves as a major endocrine organ, producing a wide variety of bioactive molecules, collectively termed adipokines, with endocrine, paracrine and autocrine activities. Adipose tissue is indeed a complex organ wherein mature adipocytes coexist with the various cell types comprising the stromal-vascular fraction (SVF), including preadipocytes, adipose-derived stem cells, perivascular cells, and blood cells. It is known that not only mature adipocytes but also the components of SVF produce adipokines. Furthermore, adipokine production, proliferative and metabolic activities and response to regulatory signals (i.e. insulin, catecholamines) differ between the different fat depots, which have been proposed to underlie their distinct association to specific diseases. Herein, we discuss the recent proteomic studies on adipose tissue focused on the analysis of the separate cellular components and their secretory products, with the aim of identifying the basic features and the contribution of each component to different adipose tissue-associated pathologies.

Relationship between Serum Lipoprotein Ratios and Insulin Resistance in Polycystic Ovary Syndrome

Objective. To investigate the association between serum lipoprotein ratios and insulin resistance in women with polycystic ovarian syndrome (PCOS). Methods. 105 PCOS patients and 109 controls were randomly enrolled in the study. Serum levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol (E2), total testosterone (T), fasting glucose (FBG), fasting insulin (FINS), serum triglycerides (TG), total cholesterol (TC), high-density lipoprotein (HDL-C), and low-density lipoprotein (LDL-C) levels were checked, and then TG/HDL-C ratio, TC/HDL-C, ratio and LDL-C/HDL-C ratio were calculated. The homeostasis model assessment of insulin resistance (HOMA-IR) was used to calculate the insulin resistance. Results. All lipoprotein ratios were significantly higher in PCOS patients as compared to healthy controls (P < 0.05). TG/HDL-C ratio, TC/HDL-C ratio, and LDL-C/HDL-C ratio were significantly correlated with HOMA-IR (P < 0.05). The ROC curve demonstrated that TC/HDL-C ratio had higher sensitivity and specificity in diagnosing PCOS with insulin resistance. Conclusion. This study demonstrates that serum lipoprotein ratio significantly correlates with insulin resistance and can be used as the marker of insulin resistance in PCOS patients.

Glycated human DNA is a preferred antigen for anti-DNA antibodies in diabetic patients

AIMS

Glycation of proteins and DNA, results in the generation of free radicals causing structural modification of biomacromolecule. This leads to the generation of neo-antigenic epitopes having implication in diabetes mellitus. In this study, human placental DNA was glycated with fructose and its binding was probed with the serum antibodies from type 1 and 2 diabetes patients.

METHODS

Glycation was carried out by incubating DNA (10 μg/ml) with fructose (25 mM) for 5 days at 37°C. The induced structural changes in DNA were studied by spectroscopic techniques, thermal denaturation studies and agarose gel electrophoresis. Furthermore, binding characteristics of autoantibodies in diabetes (type 1 and 2) patients were assessed by direct binding and competitive ELISA.

RESULTS

DNA glycation with fructose resulted in single strand breaks, hyperchromicity in UV spectrum and increased fluorescence intensity. Thermal denaturation studies demonstrated the unstacking of bases and early onset of duplex unwinding. Type 1 diabetes patients exhibited enhanced binding with glycated DNA as compared to native form, while for type 2 diabetes only those with secondary complications (Nephropathy) showed higher binding.

CONCLUSIONS

Glycation of DNA has resulted in structural perturbation causing generation of neo-antigenic epitopes that are better antigens for antibodies in diabetes patients.