Role for GLUT1 in diabetic glomerulosclerosis

Numerous studies have investigated specific pathways that link diabetes and high extracellular glucose exposure to glomerulosclerosis and mesangial cell extracellular matrix production. However, only in the past ten years has a role for glucose transporters in this process been addressed. Many different glucose transporters are expressed in glomeruli; of these, the GLUT1 facilitative glucose transporter is upregulated in the diabetic renal cortex and in response to glomerular hypertension, as well as in cultured mesangial cells exposed to high glucose. Transgenic mouse and cell models have recently been developed to test the role of GLUT1 in the pathogenesis of glomerulosclerosis with and without diabetes. Clinical studies of GLUT1 alleles performed in humans have identified GLUT1 susceptibility alleles for diabetic nephropathy. Studies are also currently under way to assess the potential role of GLUT1 in nondiabetic renal disorders.     

Combination therapy: A new strategy to manage diabetes and its complications

Diabetes mellitus is the most common metabolic disorder. The major cause of mortality and morbidity here is due to the complications caused by increased glucose concentrations. All the available commercial antidiabetic drugs are associated with side effects. The combination therapy could be a new and highly effective therapeutic strategy to manage hyperglycemia. Combination of commercial drugs with phytochemicals may reduce the side effects caused by these synthetic drugs. Herbal products have been thought to be inherently safe, because of their natural origin and traditional use rather than based on systemic studies. New formulation and cocrystallisation strategies need to be adopted to match the bioavailability of the drug and the phytochemical. This review describes in detail, the observed synergy and mechanism of action between phytochemicals and synthetic drugs in effectively combating. The mode of action of combination differs significantly than that of the drugs alone; hence isolating a single component may lose its importance thereby simplifying the task of pharma industries.     

Suppression of PPAR-gamma attenuates insulin-stimulated glucose uptake by affecting both GLUT1 and GLUT4 in 3T3-L1 adipocytes

Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) plays a critical role in regulating insulin sensitivity and glucose homeostasis. In this study, we identified highly efficient small interfering RNA (siRNA) sequences and used lentiviral short hairpin RNA and electroporation of siRNAs to deplete PPAR-gamma from 3T3-L1 adipocytes to elucidate its role in adipogenesis and insulin signaling. We show that PPAR-gamma knockdown prevented adipocyte differentiation but was not required for maintenance of the adipocyte differentiation state after the cells had undergone adipogenesis. We further demonstrate that PPAR-gamma suppression reduced insulin-stimulated glucose uptake without affecting the early insulin signaling steps in the adipocytes. Using dual siRNA strategies, we show that this effect of PPAR-gamma deletion was mediated by both GLUT4 and GLUT1. Interestingly, PPAR-gamma-depleted cells displayed enhanced inflammatory responses to TNF-alpha stimulation, consistent with a chronic anti-inflammatory effect of endogenous PPAR-gamma. In summary, 1) PPAR-gamma is essential for the process of adipocyte differentiation but is less necessary for maintenance of the differentiated state, 2) PPAR-gamma supports normal insulin-stimulated glucose transport, and 3) endogenous PPAR-gamma may play a role in suppression of the inflammatory pathway in 3T3-L1 cells.     

A new technique to prevent self-ligation of DNA

The most widely used technique for preventing self-ligation (self-circularization and concatenation) of DNA is dephosphorylation of the 5'-end, which stops DNA ligase from catalyzing the formation of phosphodiester bonds between the 3'-hydroxyl and 5'-phosphate residues at the DNA ends. The 5'-dephosphorylation technique cannot be applied to both DNA species to be ligated and thus, the untreated DNA species remains capable of self-ligation. To prevent this self-ligation, we replaced the 2'-deoxyribose at the 3'-end of the untreated DNA species with a 2',3'-dideoxyribose. Self-ligation was prevented at the replaced 3'-end, while the 5'-phosphate remaining at the 5'-end permitted ligation with the 3'-hydroxyl end of the 5'-dephosphorylated DNA strand. We successfully applied this 3'-replacement technique to gene cloning, adapter-mediated polymerase chain reaction and messenger RNA fingerprinting. The 3'-replacement technique is simple and not restricted by sequence or conformation of the DNA termini and is thus applicable to a wide variety of methods involving ligation.     

Renal GLUT1 reduction depends on angiotensin-converting enzyme inhibition in diabetic hypertensive rats

AimsAngiotensin-converting enzyme (ACE) inhibitors are used in diabetic kidney disease to reduce systemic/intra-glomerular pressure. The objective of this study was to investigate whether reducing blood pressure (BP) could modulate renal glucose transporter expression, and urinary markers of diabetic nephropathy in diabetic hypertensive rats treated with ramipril or amlodipine.Main methodsDiabetes was induced in spontaneously-hypertensive rats (~ 210 g) by streptozotocin (50 mg/kg). Thirty days later, animals received ramipril 15 μg/kg/day (R, n = 10), or amlodipine 10 mg/kg/day (A, n = 8,) or water (C, n = 10) by gavage. After 30-day treatment, body weight, glycaemia, urinary albumin and TGF-β1 (enzyme-linked immunosorbent assay) and BP (tail-cuff pressure method) were evaluated. Kidneys were removed for evaluation of renal cortex glucose transporters (Western blotting) and renal tissue ACE activity (fluorometric assay).Key findingsAfter treatments, body weight (p = 0.77) and glycaemia (p = 0.22) were similar among the groups. Systolic BP was similarly reduced (p < 0.001) in A and R vs. C (172.4 ± 3.2; 186.7 ± 3.7 and 202.2 ± 4.3 mm Hg; respectively). ACE activity (C: 0.903 ± 0.086; A: 0.654 ± 0.025, and R: 0.389 ± 0.057 mU/mg), albuminuria (C: 264.8 ± 15.4; A: 140.8 ± 13.5 and R: 102.8 ± 6.7 mg/24 h), and renal cortex GLUT1 content (C: 46.81 ± 4.54; A: 40.30 ± 5.39 and R: 26.89 ± 0.79 AU) decreased only in R (p < 0.001, p < 0.05 and p < 0.001; respectively).SignificanceWe concluded that the blockade of the renin–angiotensin system with ramipril reduced early markers of diabetic nephropathy, a phenomenon that cannot be specifically related to decreased BP levels.     

Suppression of mitochondrial response to hepatectomy in diabetic rats

In non-diabetic rats, the mitochondrial phosphorylative activity per unit of cytochrome a(+a₃) in the remnant liver 3 hours after hepatectomy increased to approximately 140% of sham-operated controls without significant decrease in the energy charge. In diabetic rats the enhancement in mitochondrial phosphorylative activity following hepatectomy was inhibited in proportion to the severity of impaired insulin secretion, with a concomitant decrease in hepatic energy charge. It is suggested that insulin plays an important role in initiating an enhancement of mitochondrial oxidative phosphorylation.     

抗生素耐药防控的One Health策略

抗生素耐药作为威胁公共卫生的巨大挑战已经制约了世界经济发展。我国抗生素使用量大,是世界上抗生素滥用最严重的国家之一。文中对人群、食用动物、环境中抗生素耐药产生的原因以及抗生素耐药现状进行综述,针对我国目前抗生素使用与耐药情况,从One Health理念提出了促进抗生素的科学使用、积极探索新型抗生素研发、建立抗生素立体监测网络系统、推广抗生素耐药教育、预防感染等措施,呼吁建立跨学科、跨部门、跨地域的交流与合作,推进我国抗生素耐药防控工作进一步开展,加强环境保护,维护人类与动物的共同健康。     

Differential sensitivity of GLUT1- and GLUT2-expressing beta cells to streptozotocin.

Streptozotocin injection in animals destroys pancreatic beta cells, leading to insulinopenic diabetes. Here, we evaluated the toxic effect of streptozotocin (STZ) in GLUT2(-/-) mice reexpressing either GLUT1 or GLUT2 in their beta cells under the rat insulin promoter (RIPG1 x G2(-/-) and RIPG2 x G2(-/-) mice, respectively). We demonstrated that injection of STZ into RIPG2 x G2(-/-) mice induced hyperglycemia (>20 mM) and an approximately 80% reduction in pancreatic insulin content. In vitro, the viability of RIPG2 x G2(-/-) islets was also strongly reduced. In contrast, STZ did not induce hyperglycemia in RIPG1 x G2(-/-) mice and did not reduce pancreatic insulin content. The viability of in vitro cultured RIPG1 x G2(-/-) islets was also unaffected by STZ. As islets from each type of transgenic mice were functionally indistinguishable, these data strongly support the notion that STZ toxicity toward beta cells depends on the expression of GLUT2.     

SIRT1: A novel target to prevent atherosclerosis

Atherosclerosis is a chronic immuno‐inflammatory disease associated with blood lipids disorder. Many studies have demonstrated that caloric restriction (CR) can prevent atherosclerosis and extend lifespan. Sir2 protein, mammal's SIRT1, has been reported to at least partly contribute to the protective effect of CR. Hence, we hypothesize that SIRT1 is a key regulator in the pathogenesis of atherosclerosis and that upregulation of SIRT1 in endothelial cells may mimic CR's beneficial effect on vascular health. The recent studies have demonstrated that endothelial SIRT1 is an anti‐atherosclerosis factor and the possible mechanism may be related to inhibit oxidized low‐density lipoprotein (oxLDL)‐induced apoptosis, upregulate endothelial nitric oxide synthase (eNOS) expression, and improve endothelium relaxation function. We infer that SIRT1 may be a novel target for atherosclerosis prevention and treatment. J. Cell. Biochem. 108: 10–13, 2009. © 2009 Wiley‐Liss, Inc.     

A new strategy to infer circularity applied to four new complete frog mitogenomes

We applied a novel strategy to infer sequence circularity and complete assembly of four mitochondrial genomes (mitogenomes) of the frog families Bufonidae (Melanophryniscus moreirae), Dendrobatidae (Hyloxalus subpunctatus and Phyllobates terribilis), and Scaphiopodidae (Scaphiopus holbrookii). These are the first complete mitogenomes of these four genera and Scaphiopodidae. We assembled mitogenomes from short genomic sequence reads using a baiting and iterative mapping strategy followed by a new ad hoc mapping strategy developed to test for assembly circularization. To assess the quality of the inferred circularization, we used Bowtie2 alignment scores and a new per‐position sequence coverage value (which we named “connectivity”). Permutation tests with 400 iterations per specimen and 1% or 5% chance of mutation at the ends of the putative circular sequences showed that the proposed method is highly sensitive, with a single nucleotide insertion or deletion being sufficient for circularity to be rejected. False positives comprised only 2% of all observations and possessed significantly lower alignment scores. The size, gene content, and gene arrangement of each mitogenome differed among the species but matched the expectations for their clades. We argue that basic studies on circular sequences can benefit from the results and bioinformatics procedures introduced here, especially when closely related references are lacking.     

1H NMR metabonomics approach to the disease continuum of diabetic complications and premature death

Subtle metabolic changes precede and accompany chronic vascular complications, which are the primary causes of premature death in diabetes. To obtain a multimetabolite characterization of these high‐risk individuals, we measured proton nuclear magnetic resonance (¹H NMR) data from the serum of 613 patients with type I diabetes and a diverse spread of complications. We developed a new metabonomics framework to visualize and interpret the data and to link the metabolic profiles to the underlying diagnostic and biochemical variables. Our results indicate complex interactions between diabetic kidney disease, insulin resistance and the metabolic syndrome. We illustrate how a single ¹H NMR protocol is able to identify the polydiagnostic metabolite manifold of type I diabetes and how its alterations translate to clinical phenotypes, clustering of micro‐ and macrovascular complications, and mortality during several years of follow‐up. This work demonstrates the diffuse nature of complex vascular diseases and the limitations of single diagnostic biomarkers. However, it also promises cost‐effective solutions through high‐throughput analytics and advanced computational methods, as applied here in a case that is representative of the real clinical situation.     

Anti-angiogenesis: A new potential strategy to inhibit restenosis

Microvessels are an integral component of the neointima developing in response to the acute vascular injury resulting from angioplasty. These vessels originate from the vasa vasorum of the adventitia, and as such appear similar to the microvessels present in atherosclerotic plaques. Several angiogenic factors have been found in atherosclerotic plaques and have been associated with increased microvascularity. In addition, most of these agents - either directly or indirectly - also induce smooth muscle cell (SMC) proliferation, an essential component of the developing neointima. We therefore propose: (1) these newly formed blood vessels are necessary for the development, maintenance, and expansion of the neointimal lesions present in restenosis; (2) the initiation, regulation and maintenance of these vessels is, at least in part, due to the coordinate sequential expression of hypoxia-inducible factor 1 (HIF-1), vascular endothelial growth factor (VEGF), angiopoietin-1 (Ang-1), and/or other angiogenic factors such as the fibroblast growth factor (FGF) family of proteins; (3) targeted disruption of the signal transduction pathways modulated by these molecules may reduce vasa vasorum expansion and SMC proliferation. These effects, in turn, may inhibit neointimal expansion and thus the development of restenosis, especially following stenting.     

Triamcinolone up‐regulates GLUT 1 and GLUT 3 expression in cultured human placental endothelial cells

The placenta is a glucocorticoid target organ, and glucocorticoids (GCs) are essential for the development and maturation of fetal organs. They are widely used for treatment of a variety of diseases during pregnancy. In various tissues, GCs have regulated by glucose transport systems; however, their effects on glucose transporters in the human placental endothelial cells (HPECs) are unknown. In the present study, HPECs were cultured 24 h in the presence or absence of 0·5, 5 and 50 µmol·l^–1 of synthetic GC triamcinolone (TA). The glucose carrier proteins GLUT 1, GLUT 3 and GC receptor (GR) were detected in the HPECs. We showed increased expression of GLUT 1 and GLUT 3 proteins and messenger RNA (mRNA) levels (p < 0·05) after 24‐h cell culture in the presence of 0·5, 5 and 50 µmol·l^‐1 of TA. In contrast, GR protein and mRNA expressions were down‐regulated (p < 0·05) with 0·5, 5 and 50 µmol·l^–1 of TA 24‐h cell culture. The results demonstrate that GCs are potent regulators of placental GLUT 1 and GLUT 3 expression through GR. Excessive exposure to GCs causes maternal and fetal hypoglycemia and diminished fetal growth. We speculate that to compensate for fetal hypoglycemia and diminished fetal growth, the expression of placental endothelial glucose transporters might be increased. Copyright © 2011 John Wiley & Sons, Ltd.     

Combination therapy as a strategy to prevent antimalarial drug resistance

Resistance of Plasmodium falciparum to antimalarials is considered one of the factors responsible for the impairment of the malaria treatment and control worldwide. Resistance emerges as a result of selection and then disemination of spontaneous mutant parasites with reduced drug susceptibility. Combination therapy is considered as the main strategy to control antimalarial drug resistance. Currently, combination therapies that include artemisinin derivatives are highly recommended. Combination therapy has been used in Colombia for more than 20 years; however, its impact on preventing the dissemination of drug resistance is unknown. This paper reviews the theoretical bases and clinical studies that support the use of combination therapy.     

Surface implantation treatments to prevent infection complications in short term devices

Surface treatments of short term devices are actually evaluated to reduce the risk of infections, which in particular are one of the main causes of complications following catheter insertion. We have investigated the efficacy of ion beam techniques to reduce bacterial adhesion-or to induce bactericidal activity of different polymer materials: PVC, silicone rubber, poly(urethane) and poly(ethylene). Two routes have been evaluated, based on the production of non fouling surfaces, through the production of diamond-like surfaces upon irradiation with rare gases, or the implantation of silver, known for its bactericidal action. In this contribution we discuss more specifically the treatment of poly(ethylene), where a broad range of surface characterisation techniques could show that the biological activity resulted from the formation of metallic colloidal silver near the surface of the polymer, associated to the formation of a dense surface acting as a diffusion barrier. Reduction of the implantation energy to 10 keV, led to activity enhancement resulting from the easier accessibility of surface colloids evidenced by AFM microscopy. This study emphasises the specific processes induced by the formation of silver nano-particles at low energy implantation, which differs basically from Ion Beam Assisted Deposition (IBAD technique) leading to the formation of a continuous silver coating (Artif. Organs 18 (1994) 266; International Patent (PCT) WO 95/18637 (1995)).     

A novel improved therapy strategy for diabetic nephropathy

Diabetic nephropathy (DN), is a disorder that causes significant morbidity and mortality. Studies on the pathological mechanisms of DN reveal that advanced glycation end products (AGEs) play an important role in the pathogenesis of DN through interacting with receptors for advanced glycation end products (RAGE), which activate a series of intracellular signaling pathways. AGEs and RAGE have therefore been considered to be two potential key targets. Although multiple studies have been made for anti-DN therapy against AGEs or RAGE, the results have been disappointing due to poor effectiveness or to side effects in clinical practice. In this hypothesis article, we propose a novel treatment based on a dual-target approach. A kind of multi-functional intelligent nanoparticle is constructed, which has a core-shell nanoparticle structure to load the dual-target drugs (AGEs inhibitors and RAGE inhibitors), and has a functional “RAGE analog” to be used as “bait” to catch AGEs and target them to the kidney. Owing to its advantages of having a dual-target, synergistic effect and high efficiency, the proposition may have potential applications in DN therapy.