Bioactivity evaluation of least explored traditionally acclaimed medicinally potent herb Nanorrhinum ramosissimum(Wall. ) Betsche

Abstract Present study analysed the therapeutic potential of traditionally acclaimed medicinal herb Nanorrhinum ramosissimum, using plant parts extracted with different solvents (10 mg/mL). Shoot extracts exhibited comparatively better antimicrobial properties, in comparison to root extracts. Total phenolic content was estimated, to ascertain its dependency on antioxidant properties of plant extracts. Antioxidant assay revealed promising results in comparison to IC50 value of standard ascorbic acid (52.2±0.07 µg/mL), for methanolic extracts of shoot (61.07±0.53 µg/mL and 64.33±0.33 µg/mL) and root (76.705±0.12 µg/mL and 89.73±0.28 µg/ mL) for in vivo and in vitro regenerants respectively. Correlation coefficient R2 values ranged between 0.90-0.95, indicating a positive correlation between phenolic contents and antioxidant activity. Plant extracts were also able to inhibit DNA oxidative damage again indicating their antioxidative potential. Antidiabetic potential was confirmed by alpha amylase inhibition assay where shoot methanolic extracts (invivo, in vitro) exhibited the best IC50 values (54.42±0.16 µg/mL, 66.09±0.12 µg/mL) in comparison to standard metformin (41.92±0.08 µg/mL). Ethanolic extracts of roots (in vitro, invivo) exhibited the relative IC50 values (88.97±0.32µg/mL,96.63±0.44 µg/mL) indicating that shoot parts had a better alpha amylase inhibition property; thus proving the herb's bioactive potential and its prospective therapeutic source for curing various ailments.

Stroke in the patient with diabetes (Part 2) - Prevention and the effects of glucose lowering therapies.

There is a higher incidence of stroke in both the type 2 diabetic and the non-diabetic insulin resistant patient which is accompanied by higher morbidity and mortality. Stroke primary prevention can be achieved by controlling atrial fibrillation and hypertension, and the utilization of statins and anticoagulant therapies. Utilizing pioglitazone and GLP-1 receptor agonists reduce the risk of stroke while the utilization of metformin, α-glucosidase inhibitors, DPP-4 and SGLT-2 inhibitors have no effect. Insulin use may be a marker of increased risk of stroke, but not necessarily causative. Utilizing intravenous insulin to normalize plasma glucose levels in the acute phase of a stroke does not improve the outcome. Antiplatelet agents are not proven to be of benefit in primary prevention whereas the use of direct-acting oral anticoagulants to avoid stroke and the early use of tpA in the acute phase have been shown to be beneficial.

Effects of a new thiazolidine compound (GQ-11) on tissue repair process in models of insulin resistance and ischemia-reperfusion / Efeitos de um novo derivado tiazolidínico (GQ-11) no processo de reparo tecidual em modelos de resistência à insulina e isquemia-reperfusão

The thiazolidinediones (TZDs) class comprises drugs with hypoglycemic effects, reducing insulin resistance in peripheral tissues. Our group has demonstrated in preliminary in vivo studies that a new TZD, GQ-11, improves insulin resistance as well as modulates cytokines involved in inflammatory process, suggesting an interesting approach for therapeutic alternatives in tissue repair, especially in metabolic decompensation cases, as insulin resistance and ischemia-reperfusion. In this context, the aim of this study was to investigate GQ-11 effects in tissue repair in three different models: insulin resistance in db/db mice, reconstructed human epidermis (RHE) in glycated collagen matrix and ischemia/reperfusion induced by aorta clamping in Wistar rats. In insulin resistance context, GQ-11 treatment upregulated the expression of anti-inflammatory mediators, such as IL-10, TGF-ß and Arg-1, downregulated the expression of pro-inflammatory cytokines both in db/db mice wounds and in macrophage, besides increasing re-epithelization and collagen deposition. In addition, the treatment also induced keratinocytes proliferation and fibroblasts differentiation in RHE. In ischemia-reperfusion model, the same anti-inflammatory effect was observed along with anti-oxidant properties through regulation of enzymes, such as catalase and GPx, as well as by decreasing TBARS formation. Animals imaging by positron emission tomography (PET) indicated significant less 18F-FDG uptake in animal treated with GQ-11 compared to controls, suggesting decrease of the inflammation process related to reperfusion after aorta clamping. Concluding, the dual PPARα/γ agonist GQ-11 has an important antiinflammatory effect, suggesting a new approach to tissue repair management in diabetes and in prevention of ischemia-reperfusion syndrome post-surgery

As tiazolidinadionas (TZDs) compreendem uma classe de fármacos hipoglicemiantes que reduzem a resistência à insulina pelos tecidos periféricos. Dados preliminares in vivo obtidos em nosso grupo de pesquisa mostraram que um dos novos derivados tiazolidínicos, GQ-11, além de aumentar a resposta à insulina, pode inibir citocinas pró-inflamatórias, o que a torna uma alternativa terapêutica promissora no reparo tecidual, em especial, nos casos de descompensação metabólica como ocorre na resistência à insulina e na isquemia/reperfusão. Nesse contexto, o objetivo deste trabalho foi investigar os efeitos da GQ-11 nas etapas do processo de reparo tecidual em três modelos: resistência à insulina utilizando camundongos db/db, epiderme humana reconstruída em matriz de colágeno glicado e isquemia/reperfusão induzida por clampeamento da aorta em ratos Wistar. No contexto de resistência à insulina, o tratamento com GQ-11 induziu a expressão de mediadores anti-inflamatórios como IL-10, TGF-ß e Arg-1 e diminuiu a expressão de citocinas pró-inflamatórias em lesões de camundongos db/db e em macrófagos, além de aumentar a capacidade de re-epitelização e a deposição de colágeno. Além disso, o tratamento também induziu a proliferação de queratinócitos e a diferenciação de fibroblastos em epiderme humana reconstruída em matriz de colágeno glicado. No modelo de isquemia-reperfusão, o mesmo efeito anti-inflamatório da GQ-11 foi observado ao lado de efeitos anti-oxidantes através da regulação de enzimas como catalase, GPx e diminuição de TBARS. O imageamento dos animais através de tomografia por emissão de pósitrons (PET) demonstrou menor captação de 18F-FDG (18F-fluordesoxiglicose), indicando diminuição do processo inflamatório decorrente da reperfusão pós clampeamento aórtico. Dessa forma, conclui-se que GQ-11, um agonista dual de PPARα/γ, tem efeito anti-inflamatório importante, podendo ser um candidato à fármaco com possível aplicação no reparo tecidual no diabetes e na prevenção da síndrome de isquemia-reperfusão desenvolvida após procedimentos cirúrgicos

Glucagon receptor signaling in metabolic diseases.

Glucagon is a peptide hormone secreted from the pancreatic alpha cells in response to hypoglycemia but in some patients with type 2 diabetes a paradoxical hypersecretion results from the intake of glucose. In rodent, antagonizing the actions of glucagon have been shown to be effective for lowering blood glucose levels and this has recently have been solidified in patients with type 2 diabetes. Although the reported increases of liver enzymes, hyperglucagonemia, and alpha cell hyperplasia resulting from glucagon receptor antagonism may potentially limit the clinical applicability of glucagon receptor antagonists, they may serve as an instrumental toolbox for delineating the physiology of glucagon. Agonizing glucagon receptor signaling may be relevant, in particular when combined with glucagon-like peptide-1 receptor analogues in the perspective of body weight lowering therapy. Here, we will focus on new conceptual aspects of glucagon biology and how this may led to new diagnostics and treatment of metabolic diseases.

5,4'-Dihydroxy-7,8-dimethoxyflavanone and Aliarin from Dodonaea viscosa Are Activators of PPARγ.

PPARγ agonists are widely used medications in diabetes mellitus therapy. Their role in improving adipose tissue function contributes to antidiabetic effects. The extracts of Dodonaea viscosa have been reported to exert antidiabetic activity. However, the effective mediators and the underlying mechanisms were largely unknown. In this study, we investigated the action on PPARγ transactivation and adipocyte modulation of two typical flavonoid constituents from D. viscosa, 5,4'-dihydroxy-7,8-dimethoxyflavanone and aliarin. Our results showed that 5,4'-dihydroxy-7,8-dimethoxyflavanone and aliarin were potential partial PPARγ agonists. The compounds induced adipogenesis in 3T3-L1 cells, with an upregulated adiponectin mRNA level and enhanced insulin sensitivity. The favorable effects of 5,4'-dihydroxy-7,8-dimethoxyflavanone, aliarin, and other flavonoid constituents on adipocytes might contribute to the antidiabetic efficacy of D. viscosa.

Incretin hormones and maturity onset diabetes of the young--pathophysiological implications and anti-diabetic treatment potential.

Maturity onset diabetes of the young (MODY) designates monogenic forms of non-autoimmune diabetes characterised by autosomal dominant inheritance, non-insulin dependent diabetes at onset and diagnosis often before 25 years of age. MODY constitutes genetically and clinically heterogeneous forms of diabetes. More than 8 different genes are known to cause MODY, among which hepatocyte nuclear factor 1 alpha (HNF1A) (MODY3) and glucokinase (GCK) (MODY2) mutations are the most common. Both forms of MODY are characterised by specific beta cell dysfunction, with patients with HNF1A-diabetes having a reduced insulin secretory capacity, while patients with GCK-diabetes have a glucose-sensing defect, but preserved insulin secretory capacity. Patients with MODY are effectively treated with sulphonylurea (SU) due to very high sensitivity to these drugs, but they are also prone to develop hypoglycaemia. The objectives of this thesis were to study the pathophysiology of GCK-diabetes and HNF1A-diabetes by investigating the incretin effect, the physiological response to food ingestion and to estimate the treatment potential of a glucagon-like peptide-1 receptor agonist (GLP-1RA) in patients with HNF1A-diabetes. In Study I we investigated the incretin effect and the responses of islet hormones and incretin hormones to oral glucose tolerance test (OGTT) and isoglycaemic IV glucose infusion (IIGI) in patients with GCK-diabetes, in patients with HNF1A-diabetes, and in BMI and age matched healthy individuals (CTRLs). In Study II we investigated responses of islet hormones and incretin hormones to a more physiological stimulus consisting of a standardised meal test in patients with GCK-diabetes, in patients with HNF1A--diabetes, and in BMI and age matched CTRLs. In Study III we conducted a randomised, double-blind, crossover trial investigating the glucose lowering effect and risk of hypoglycaemia during 6 weeks of treatment with the GLP-1RA, liraglutide compared to the SU, glimepiride in 16 patients with HNF1A-diabetes. At baseline and at the end of each treatment period a standardised meal test followed by a light bicycling test was performed. The results of the studies showed that patients with HNF1A-diabetes were less glucose tolerant than patients with GCK-diabetes, but both groups were more glucose intolerant than CTRLs. In spite of glucose intolerance patients with GCK-diabetes showed normal incretin effect, whereas patients with HNF1A-diabetes showed an impaired incretin effect. Patients with HNF1A-diabetes were also characterised by an inappropriate insulin response. Normal insulin sensitivity was found in both groups of diabetes patients. In the prospective intervention trial a glucose lowering effect on fasting plasma glucose (FPG) was demonstrated with both treatments without significant difference between the treatments. The postprandial plasma glucose responses were also lower with both glimepiride and liraglutide compared to baseline without significant difference between treatments. In spite of these findings glimepiride seems to have superior glucose lowering effects according to both FPG and postprandial glucose responses. Hypoglycaemic events (plasma glucose ≤ 3.9 mM) occurred 18 times during glimepiride treatment and once during liraglutide treatment. No differences between treatments were demonstrated according to insulin and glucagon responses and gastric emptying, and counter-regulatory responses were preserved during both treatments. No effect of either treatment was seen on fructosamine or HbA1c. In conclusion, patients with GCK-diabetes show normal incretin and glucagon physiology, thus resembling healthy individuals, in spite of fasting hyperglycaemia and subtle glucose intolerance. In contrast, patients with HNF1A-diabetes exhibited noticeable glucose intolerance, beta cell dysfunction, impaired incretin effect, and inappropriate glucagon response to oral stimuli, hence resembling patients with type 2 diabetes. However, normal responses of incretin hormones and normal insulin sensitivity were found in patients with HNF1A-diabetes. Six weeks of treatment with glimepiride or liraglutide demonstrated glucose lowering effects. This effect was greater with glimepiride, although insignificant, but at the expense of a higher risk of hypoglycaemia (predominantly mild). GLP-1RAs may have a place in treatment of patients with HNF1A-diabetes, especially when hypoglycaemia is a problem. Future studies are required to clarify this.

Salicylate activates AMPK and synergizes with metformin to reduce the survival of prostate and lung cancer cells ex vivo through inhibition of de novo lipogenesis.

Aspirin, the pro-drug of salicylate, is associated with reduced incidence of death from cancers of the colon, lung and prostate and is commonly prescribed in combination with metformin in individuals with type 2 diabetes. Salicylate activates the AMP-activated protein kinase (AMPK) by binding at the A-769662 drug binding site on the AMPK ß1-subunit, a mechanism that is distinct from metformin which disrupts the adenylate charge of the cell. A hallmark of many cancers is high rates of fatty acid synthesis and AMPK inhibits this pathway through phosphorylation of acetyl-CoA carboxylase (ACC). It is currently unknown whether targeting the AMPK-ACC-lipogenic pathway using salicylate and/or metformin may be effective for inhibiting cancer cell survival. Salicylate suppresses clonogenic survival of prostate and lung cancer cells at therapeutic concentrations achievable following the ingestion of aspirin (<1.0 mM); effects not observed in prostate (PNT1A) and lung (MRC-5) epithelial cell lines. Salicylate concentrations of 1 mM increased the phosphorylation of ACC and suppressed de novo lipogenesis and these effects were enhanced with the addition of clinical concentrations of metformin (100 µM) and eliminated in mouse embryonic fibroblasts (MEFs) deficient in AMPK ß1. Supplementation of media with fatty acids and/or cholesterol reverses the suppressive effects of salicylate and metformin on cell survival indicating the inhibition of de novo lipogenesis is probably important. Pre-clinical studies evaluating the use of salicylate based drugs alone and in combination with metformin to inhibit de novo lipogenesis and the survival of prostate and lung cancers are warranted.

Lipoatrophy in children with type 1 diabetes: an increasing incidence?

The objectives were to evaluate the current prevalence of lipoatrophy at insulin injection sites in young patients with type 1 diabetes. Standardized examination of insulin injection sites in all 678 patients with type 1 diabetes treated in 2013 in our outpatient clinic were conducted. In case of lipoatrophy photo documentation and standardized interview with parents and patients were performed. We identified a total of 16 patients (43.8% male) with lipoatrophy (overall prevalence 2.4%). The current mean age (±SD) of the affected patients was 14.4 ± 3.9 years, age and diabetes duration at onset of lipoatrophy were 11.5 ± 3.8 years and 5.4 ± 3.6 years, respectively. All patients were using analogs at the onset of lipoatrophy. In all, 14 of 16 patients (87.5%) were on insulin pump compared with 52% without lipoatrophy (P = .0018). The use of steel needle and Teflon catheter was equal between the pump patients. Concomitant autoimmune diseases were present in 37.5% of the patients (thyroiditis: n = 3, thyroiditis and celiac disease: n = 2, celiac disease: n = 1) compared with 15.0% in those without lipoatrophy (P = .0128). Lipoatrophy was present in young patients treated with modern insulins and pumps; however, the prevalence was relatively low as expected with the use of modern insulins. Our data may support the hypothesis that a constant mechanical element such as a subcutaneous catheter may trigger the development of lipoatrophy, particularly in those patients with more than 1 autoimmune disease.

The cholesterol-lowering agent methyl-ß-cyclodextrin promotes glucose uptake via GLUT4 in adult muscle fibers and reduces insulin resistance in obese mice.

Insulin stimulates glucose uptake in adult skeletal muscle by promoting the translocation of GLUT4 glucose transporters to the transverse tubule (T-tubule) membranes, which have particularly high cholesterol levels. We investigated whether T-tubule cholesterol content affects insulin-induced glucose transport. Feeding mice a high-fat diet (HFD) for 8 wk increased by 30% the T-tubule cholesterol content of triad-enriched vesicular fractions from muscle tissue compared with triads from control mice. Additionally, isolated muscle fibers (flexor digitorum brevis) from HFD-fed mice showed a 40% decrease in insulin-stimulated glucose uptake rates compared with fibers from control mice. In HFD-fed mice, four subcutaneous injections of MßCD, an agent reported to extract membrane cholesterol, improved their defective glucose tolerance test and normalized their high fasting glucose levels. The preincubation of isolated muscle fibers with relatively low concentrations of MßCD increased both basal and insulin-induced glucose uptake in fibers from controls or HFD-fed mice and decreased Akt phosphorylation without altering AMPK-mediated signaling. In fibers from HFD-fed mice, MßCD improved insulin sensitivity even after Akt or CaMK II inhibition and increased membrane GLUT4 content. Indinavir, a GLUT4 antagonist, prevented the stimulatory effects of MßCD on glucose uptake. Addition of MßCD elicited ryanodine receptor-mediated calcium signals in isolated fibers, which were essential for glucose uptake. Our findings suggest that T-tubule cholesterol content exerts a critical regulatory role on insulin-stimulated GLUT4 translocation and glucose transport and that partial cholesterol removal from muscle fibers may represent a useful strategy to counteract insulin resistance.

[Insulin potentiating and antidepressant effects of 3-oxypyridine and succinic acid derivatives].

The dependence of the antidepressant action of 3-oxypyridine and succinic acid derivatives (emoxipine, reamberin, and mexidol) on the insulin potentiating activity of these therapeutic agents has been studied in experiments on rats. Alpha-lipoic acid was used as a reference drug. It was established that single administration of emoxipine, reamberin, mexidol and alpha-lipoic acid in optimal doses, corresponding to the therapeutic range in humans, increased the sensitivity of animals to insulin according to the criterion of insulin coma development. Triple administration of the therapeutic agents studied in the same single dose produced an antidepressant effect according to the criterion of "desperate behavior" in Porsolt forced swimming test. Standardization of obtained data by average difference from the control and further correlation analysis demonstrated that the extent of antidepressant action of emoxipine, reamberin, mexidol and alpha-lipoic acid considerably depends on their insulin potentiating activity (r = 0.762, p = 0.004).

Minimal modeling of insulin secretion in the perfused rat pancreas: a drug effect case study.

The experimental protocol of the perfused rat pancreas is commonly used to evaluate ß-cell function. In this context, mathematical models become useful tools through the determination of indexes that allow the assessment of ß-cell function in different experimental groups and the quantification of the effects of antidiabetic drugs, secretagogues, or treatments. However, a minimal model applicable to the isolated perfused rat pancreas has so far been unavailable. In this work, we adapt the C-peptide minimal model applied previously to the intravenous glucose tolerance test to obtain a specific model for the experimental settings of the perfused pancreas. Using the model, it is possible to estimate indexes describing ß-cell responsivity for first (ΦD) and second phase (ΦS, T) of insulin secretion. The model was initially applied to untreated pancreata and afterward used for the assessment of pharmacologically relevant agents (the gut hormone GLP-1, the potent GLP-1 receptor agonist lixisenatide, and a GPR40/FFAR1 agonist, SAR1) to quantify and differentiate their effect on insulin secretion. Model fit was satisfactory, and parameters were estimated with good precision for both untreated and treated pancreata. Model application showed that lixisenatide reaches improvement of ß-cell function similarly to GLP-1 (11.7- vs. 13.1-fold increase in ΦD and 2.3- vs. 2.8-fold increase in ΦS) and demonstrated that SAR1 leads to an additional improvement of ß-cell function in the presence of postprandial GLP-1 levels.

Metformin enhances cisplatin cytotoxicity by suppressing signal transducer and activator of transcription-3 activity independently of the liver kinase B1-AMP-activated protein kinase pathway.

Metformin has been used as first-line treatment in patients with type 2 diabetes, and is reported to reduce cancer risk and progression by activating the liver kinase B1 (LKB1)-AMP-activated protein kinase (AMPK) pathway. Cisplatin remains the main drug for treating advanced non-small-cell lung cancer. However, drug resistance often develops through several mechanisms during the treatment course, including one mechanism mediated by the activation of the IL-6/signal transducer and activator of transcription (STAT)-3 pathway, related to the generation of reactive oxygen species (ROS). This study demonstrated a correlation between STAT3 phosphorylation and cisplatin cytotoxicity, using AS2 (PC14PE6/AS2)-derived cell lines (AS2/S3C) that contained constitutively active STAT3 plasmids as a model. A STAT3 inhibitor (JSI-124) enhanced the cisplatin sensitivity in AS2 cells, whereas metformin inhibited STAT3 phosphorylation and enhanced cisplatin cytotoxicity. By contrast, another AMPK activator (5-aminoimidazole-4-carboxamide-riboside) failed to produce these effects. LKB1-AMPK silencing by small, interfering RNA or mammalian target of rapamycin (mTOR) inhibition by rapamycin or pp242 did not alter the effect of metformin on STAT3 activity suppression, suggesting that metformin can modulate the STAT3 pathway through an LKB1-AMPK-independent and probably mTOR-independent mechanism. Metformin also inhibited cisplatin-induced ROS production and autocrine IL-6 secretion in AS2 cells. Both mechanisms contributed to the ability of metformin to suppress STAT3 activation in cancer cells, which resulted in the decreased secretion of vascular endothelial growth factor by cancer cells. The growth of subcutaneous tumor xenografts was significantly delayed by a combination of cisplatin and metformin. This is the first study to demonstrate that metformin suppresses STAT3 activation via LKB1-AMPK-mTOR-independent but ROS-related and autocrine IL-6 production-related pathways. Thus, metformin helps to overcome tumor drug resistance by targeting STAT3.

1α,25-dihydroxyvitamin D3 and rosiglitazone synergistically enhance osteoblast-mediated mineralization.

Both vitamin D receptor (VDR) and peroxisome proliferator-activated receptor γ (PPAR-γ) are ligand-activated nuclear transcription factors that are instrumental for bone health. While 1α,25-dihydroxyvitamin D3 (1,25D3), the ligand for VDR, is essential for the development and maintenance of healthy bone, PPAR-γ agonists cause detrimental skeletal effects. Recent studies have revealed evidence for a cross-talk between 1,25D3- and PPAR-α/-δ ligand-mediated signaling but there is a current lack of knowledge regarding cross-talk between signaling of 1,25D3 and the PPAR-γ ligand mediated signaling. In this study, we investigated the cross-talk between 1,25D3- and PPAR-γ agonist rosiglitazone-mediated signaling in human osteoblasts. 1,25D3 slightly but significantly induced expression of the primary PPAR-γ target gene ANGPTL4 but did not influence FABP4. 1,25D3 did not change rosiglitazone regulation of ANGPTL4 and FABP4. The other way around, rosiglitazone reduced CYP24A1 gene expression but this did not change CYP24A1 induction by 1,25D3. The findings regarding CYP24A1 gene expression are in line with the observation that 1,25D3 levels in medium were not affected by rosiglitazone. Furthermore, rosiglitazone significantly inhibited 1,25D3-induction of BGLAP while rosiglitazone alone did not change BGLAP. Additionally, 1,25D3 and rosiglitazone increase osteoblast alkaline phosphatase activity and synergistically stimulated extracellular matrix mineralization. In conclusion, these data provide evidence for a cross-talk between rosiglitazone- and 1,25D3-mediated signaling leading to an acceleration of extracellular matrix mineralization. The data suggest that the reduction of the mineralization inhibitor BGLAP and the increased differentiation status underlie the increased mineralization.

Lactobacillus casei Shirota protects from fructose-induced liver steatosis: a mouse model.

To test the hypothesis that Lactobacillus casei Shirota (Lcs) protects against the onset of non-alcoholic fatty liver disease (NAFLD) in a mouse model of fructose-induced steatosis, C57BL/6J mice were either fed tap water or 30% fructose solution +/- Lcs for 8 weeks. Chronic consumption of 30% fructose solution led to a significant increase in hepatic steatosis as well as plasma alanine-aminotransferase (ALT) levels, which was attenuated by treatment with Lcs. Protein levels of the tight junction protein occludin were found to be markedly lower in both fructose treated groups in the duodenum, whereas microbiota composition in this part of the intestine was not affected. Lcs treatment markedly attenuated the activation of the Toll-like receptor (TLR) 4 signalling cascade found in the livers of mice only treated with fructose. Moreover, in livers of fructose fed mice treated with Lcs peroxisome proliferator-activated receptor (PPAR)-γ activity was markedly higher than in mice only fed fructose. Taken together, the results of the present study suggest that the dietary intake of Lcs protects against the onset of fructose-induced NAFLD through mechanisms involving an attenuation of the TLR-4-signalling cascade in the liver.

Extra-pancreatic effects of incretin-based therapies: potential benefit for cardiovascular-risk management in type 2 diabetes.

Development of cardiovascular disease is one of the major complications of type 2 diabetes mellitus (T2DM). The chronic hyperglycaemic state is often accompanied by dyslipidaemia, hypertension, low-grade systemic inflammation and oxidative stress which collectively result in a high risk of micro- and macrovascular complications. Current glucose-lowering agents do not sufficiently address fore-mentioned macrovascular-risk factors. Recently, new therapeutic agents were introduced, based on the incretin hormone glucagon-like peptide-1 (GLP-1), that is, the GLP-1 receptor agonists (GLP-1RA) and dipeptidyl-peptidase 4 (DPP-4) inhibitors. Beside its effect on pancreatic insulin secretion, GLP-1 exerts several extra-pancreatic effects such as slowing down gastric emptying, promoting satiety and reducing food intake and weight loss. Also, GLP-1 and GLP-1RA were shown to improve cardiovascular-risk profiles, by reducing body fat content, blood pressure, circulating lipids and inflammatory markers in patients with T2DM. This review summarizes the presently known evidence with regard to extra-pancreatic effects of the incretin-based agents, focusing on the actions that improve the cardiovascular-risk profile. We present available data from clinical trials of at least 24 week duration, but also findings from small-sized clinical 'proof of principle' studies. We conclude that GLP-1 RA and to a lesser extent DPP-4 inhibitors are promising agents with regard to their effects on body weight, blood pressure and lipids, which collectively ameliorate the cardiovascular-risk profile and as such may have added value in the treatment of T2DM. However, large-sized long-term outcome studies are warranted to show the true added value of these agents in the treatment of patients with T2DM.

Chromium infusion in hospitalized patients with severe insulin resistance: a retrospective analysis.

OBJECTIVE: To investigate the effects of intravenous chromium on serum glucose and insulin infusion rates in hospitalized patients with severe insulin resistance. METHODS: In this retrospective study, we reviewed hospital records from January 1, 2008, to December 1, 2008, to identify patients for whom intravenous chromium was ordered at our academic medical center. To be included, patients were required to demonstrate profound insulin resistance and uncontrolled hyperglycemia (defined as the inability to achieve a blood glucose value less than 200 mg/dL during the 12 hours before chromium was given despite administration of continuous insulin infusion at a rate of 20 or more units/h) and to have received a continuous infusion of chromium chloride at 20 mcg/h for 10 to 15 hours for a total dose of 200 to 240 mcg. RESULTS: Fourteen patients met our inclusion criteria. Over the hour preceding intravenous chromium infusion, the mean ± standard deviation rate of insulin infusion was 31 ± 15 units/h, and blood glucose was 326 ± 86 mg/dL. Twelve hours after the initiation of chromium, these values were 16 ± 16 units/h and 162 ± 76 mg/dL, respectively (P = .011 for difference in mean insulin rate from baseline, P<.001 for difference in mean blood glucose from baseline) and 24 hours after, these values were 12 ± 15 units/h and 144 ± 48 mg/dL, respectively (P<.001 for both). CONCLUSIONS: Intravenous chromium decreases insulin needs and improves glucose control at 12 and 24 hours compared with baseline values. Chromium appears to improve hyperglycemia and insulin resistance in acutely ill patients and represents a potential new therapy. Future prospective randomized controlled trials are needed to confirm these results.

Structural insights for the design of new PPARgamma partial agonists with high binding affinity and low transactivation activity.

Peroxisome Proliferator-Activated Receptor γ (PPARγ) full agonists are molecules with powerful insulin-sensitizing action that are used as antidiabetic drugs. Unfortunately, these compounds also present various side effects. Recent results suggest that effective PPARγ agonists should show a low transactivation activity but a high binding affinity to inhibit phosphorylation at Ser273. We use several structure activity relationship studies of synthetic PPARγ agonists to explore the different binding features of full and partial PPARγ agonists with the aim of differentiating the features needed for binding and those needed for the transactivation activity of PPARγ. Our results suggest that effective partial agonists should have a hydrophobic moiety and an acceptor site with an appropriate conformation to interact with arm II and establish a hydrogen bond with Ser342 or an equivalent residue at arm III. Despite the fact that interactions with arm I increase the binding affinity, this region should be avoided in order to not increase the transactivation activity of potential PPARγ partial agonists.

[A novel cell model targeted on GLP-1 receptor for application to anti-diabetic candidates screening].

The aim of this project is to establish a GLP-1 signaling pathway targeted cell model, for screening the new class of GLP-1 receptor agonists as anti-diabetic candidates. Firstly construct a recombined plasmid with multi-copied specific response element (RIP-CRE) regulated by GLP-1 signaling pathway and E-GFP reporter gene. Transient transfect this recombined plasmid into islet cell NIT-1, then detect the responsibility of transfected cell to GLP-1 analogue, Exendin 4. For secondly, use stable transfection and monocloning cell culture to obtain a GLP-1 signaling-specific cell line. It indicates that this cell model can response to Exendin 4, which response can be completely inhibited by GLP-1 receptor antagonist, Exendin 9-39, further showing GLP-1 receptor specific activity with a cAMP-PKA-independently mechanism. Establishment of this novel cell model can be used in high-throughput drug screening of peptides or small molecular GLP-1 analogues.

Effects of combined PPARgamma and PPARalpha agonist therapy on reverse cholesterol transport in the Zucker diabetic fatty rat.

AIM: We investigated the effects of the combined therapy of PPARgamma and PPARalpha agonists on HDL metabolism, especially concerning reverse cholesterol transport (RCT), using Zucker diabetic fatty rats (ZDF/Crl-Lepr fa rats) that are the rodent model for type 2 diabetes with obesity, hyperlipidaemia and insulin resistance. METHODS: The ZDF rats were divided into four medicated groups as follows: pioglitazone as a PPARgamma agonist (5 mg/kg/day; P group, n = 6), fenofibrate as a PPARalpha agonist (30 mg/kg/day; F group, n = 6), both these medications (P + F group, n = 6) and no treatment (UNT group, n = 6). Non-diabetic rats (ZDF/GmiCrl-lean, CON group, n = 6) served as controls. We evaluated HDL particle size and messenger RNA (mRNA) levels of the following factors: liver X receptor alpha (L x R alpha), ATP-binding cassette A1 (ABCA1) and ABCG1 which are regulated by PPARs and are related to early stage RCT. RESULTS: The significant increase in HDL particle size was demonstrated in rats of the F and P + F groups, although changes in plasma HDL-cholesterol levels were not significant. In accordance with this finding, mRNA levels of ABCG1 in the liver increased significantly. CONCLUSIONS: These findings suggest the efficacy of combined therapy with PPARgamma and PPARalpha in improving lipid metabolism, partly through the enhanced RCT, and insulin resistance in type 2 diabetes mellitus.