Upregulation of glucose uptake in L8 myotubes by the extract from Lagerstroemia speciosa: a possible mechanism of action

The leaf of Lagerstroemia speciosa L. is used as an anti-diabetic herbal remedy in many countries. In an attempt to discover mechanisms of action of the L. speciosa extract that stimulate glucose uptake, a cell-based radioactive assay of glucose uptake was performed using L8 muscle cells. In this study, the methanol fraction of L. speciosa leaves (LSE) contained a high level of phenolic compounds and showed strong capability to stimulate glucose uptake in a dose-dependent manner. The LSE stimulation was slightly inhibited (8.8%) by SB203580. The inhibitory effect (23.6%) of wortmannin on LSE-stimulated glucose uptake was demonstrated, suggesting LSE action on glucose transporter translocation. LSE-induced glucose uptake was completely reversed by cycloheximide. In addition, an increased amount of total glucose-transporter-1 protein was observed indicating that new protein synthesis is necessary for elevated glucose transport. LSE also enhanced insulin-stimulated glucose transport. These results suggest that LSE action may be mediated primarily via the synthesis of new transporters and involve both insulin-dependent and independent pathways

Expression of atrophy mRNA relates to tendon tear size in supraspinatus muscle

Skeletal muscle atrophy and fatty infiltration develop after tendon tearing. The extent of atrophy serves as one prognostic factor for the outcome of surgical repair of rotator cuff tendon tears. We asked whether mRNA of genes involved in regulation of degradative processes leading to muscle atrophy, ie, FOXOs, MSTN, calpains, cathepsins, and transcripts of the ubiquitin-proteasome pathway, are overexpressed in the supraspinatus muscle in patients with and without rotator cuff tears. We evaluated biopsy specimens collected during surgery of 53 consecutive patients with different sizes of rotator cuff tendon tears and six without tears. The levels of corresponding gene transcripts in total RNA extracts were assessed by semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Supraspinatus muscle atrophy was assessed by MRI. The area of muscle tissue (or atrophy), decreased (increased) with increasing tendon tear size. The transcripts of CAPN1, UBE2B, and UBE3A were upregulated more than twofold in massive rotator cuff tears as opposed to smaller tears or patients without tears. These atrophy gene products may be involved in cellular processes that impair functional recovery of affected muscles after surgical rotator cuff repair. However, the damaging effects of gene products in their respective proteolytic processes on muscle structures and proteins remains to be investigated

Study of fortilin interacting proteins in a human skeletal muscle using the yeast two-hybrid system

Fortilin is implicated in development, cellular processes and malignant transformation. However, a unifying picture ofproteins in key processes pertaining to fortilin function is not yet emerging. To investigate the potential interactions, humanfortilin was expressed in the yeast cells, and used to screen for fortilin binding proteins in a human skeletal muscle. Yeastcells were transformed in the sequential procedure using yeast two-hybrid expression vector (pAS2-1) containing full-lengthhuman fortilin as ‘bait’ for the first transformation, and pGAD10 vector containing a muscle cDNA library for the secondtransformation. In addition, a direct interaction of fortilin with known proteins, Ca2+-ATPase, creatine kinase, glycogenphosphorylase, and troponin C was evaluated. -Galactosidase activity was assayed as an index of interaction betweenfortilin and the potential target proteins whereas yeast mating strategy was used to eliminate false positive and to reconfirmthe actual binding. From this analysis, eukaryotic translation elongation factor-1 delta (guanine nucleotide exchange protein)was identified as a putative fortilin interacting protein

Study of fortilin interacting protein in a skeletal muscle using the yeast two-hybrid system

Prince of Songkla Universit

The biological activity of Coccinia indica on glucose transporter 1 (GLUT1) promoter

Plant derivatives with purported hypoglycemic properties have been used in traditional medicine around the world. Coccinia indica (ivy gourd) is used in traditional medicine to treat diabetics in many countries. C. indica is able to cause a reduction in blood glucose level and has shown hypoglycemic activity in vitro and in vivo. However, the mechanism of this effect remains unknown. In this study, we generated the pGL3-glucose transporter 1 (GLUT1) promoter to elucidate the molecular mechanism of the regulation of GLUT1 gene expression in response to a water extract of C. indica stem (CIextract). A fragment of 2.1 kb of rat GLUT1 promoter, located at -2,106 to +134, was linked to firefly luciferase. The regulating transcription was analyzed in transient expression assay after transfection and exposure of L6 myocytes with the GLUT1 promoter system and CI extract, respectively. Under normal condition (5 mM glucose), promoter activity induced by 0.15 mg CI extract was markedly increased by 5.71 fold from the basal value. CI extract was more effective than 2 mM metformin. Surprisingly, promoter activity in hyperglycemic condition (15 mM glucose) induced by 0.50 mg CI was increased by 1.63 fold from the basal value. In addition, CI extract increased the 2-deoxyglucose (2-DG) uptake in L6myocytes in a dose-dependent manner in both conditions, 5 mM and 15 mM glucose. GLUT1 protein was determined by Western blot analysis and the level also increased in a dose-dependent fashion. Interestingly, the activity of the -273 to +134 of GLUT1 promoter was increased by 2.12 fold from the basal value. This site is the transcription initiation site containing GC box and TATA box. These observations suggest that the hypoglycemic action of C. indica may regulate through the activation of GLUT1 promoter resulting in an increase of the GLUT1 protein expression

Proceedings of the 2005 International Conference on Simulation and Modeling

This paper proposes a coevolutionary classification method to discover classifiers for multidimensional pattern classification problems with continuous input variables. The classification problems may be decomposed into two sub-problems, which are feature selection and classifier adaptation. A coevolutionary classification method is designed by coordinating the two sub-problems, whose performances are affected by each other. The proposed method establishes a group of partial sub-regions, defined by regional variable set, and then fits a finite number of classifiers to the data pattern by combining a genetic algorithm and a local adaptation algorithm in every subregion. A cycle of the cooperation loop is completed by evolving the sub-regions based on the evaluation results of the fitted classifiers located in the corresponding subregions. The classifier system has been tested with wellknown data sets from the UCI machine-learning database, showing superior performance to other methods such as the nearest neighbor, decision tree, and neural networks

Differential Activation of Glucose Transport

Peripheral resistance to insulin is a prominent feature of both insulin-dependent and non-insulin-dependent diabetes. One of the major factors regulating glucose uptake into muscle is the quantity of glucose transporter (GLUT) protein on the cell surface. In muscle and adipocytes, GLUT1 mediates basal or nonstimulated transport, whereas GLUT4, the insulin-responsive GLUT, facilitates increased glucose transport in the presence of insulin. 1) Membrane GLUT4 is regulated by insulin via a PI3K-dependent process. 1-3) However, increased GLUT4 content is insufficient to fully account for glucose transport activity observed under insulin-stimulated conditions. Specifically, transporter translocation accounts for approximately 30% of insulin-stimulated glucose uptake while activation of GLUTs is essential for maximal stimulation. Polyphenols present in plant-derived fruits and vegetables have been implicated in mediating glucose transport in vitro and in vivo studies. 10) In addition, several polyphenolic compounds were recently reported to inhibit sodium-dependent glucose transport in intestinal epithelial cells. 11) Hence, polyphenols could play a role in controlling glucose uptake in the intestinal tract and peripheral tissues, and possibly contribute to blood glucose homeostasis. A preliminary study of plants used in Thai folkloric medicine to treat diabetes determined a distinct effect of Canna indica L. (Cannaceae) watery extract on glucose uptake activity in a cell culture model, and, hence this extract was chosen for this present study. The aim of this work was to study the mechanism of action of C. indica on the stimulation of glucose uptake in L8 muscle cells. MATERIALS AND METHODS Plant Extraction The root of CI was collected in June 2004 from the medicinal plant garden of Faculty of Pharmaceutical Sciences, Prince of Songkla University, Thailand. Samples were dried at a 45°C for 4 d and then grounded to a powder. Five grams of grounded powder were extracted with 200 ml of distilled water at 70°C for 30 min. The extract was filtered and then centrifuged at 5000 g for 20 min followed by freeze-drying (yield 72.5 mg/g dry weight). Varying concentrations in mg/ml were prepared from freeze-dry residue, and then used in further studies. Determination of Total Phenolics and Phytochemical Screening The amount of total phenolic compounds was determined spectrophotometrically using Folin-Ciocalteu reagent as described by Lee et al. 12) and was expressed in microgram of catechin equivalent (CE) based on a calibration curve for catechin. The content of total phenolics of CI root was 60.02Ϯ4.05 mg CE/mg freeze-dry residue. Phytochemical screening of CI root was performed using the methods previously described by Farnsworth 13) and Harborne 14) with slight modification. In brief, several reagents were prepared to test for the presence of flavonoids, coumarins, anthraquinones, cardiac glycosides, cyanogenetic glycosides, coumarins, saponins and tannins. The results were compared with the positive standards of each test. Cell Culture and Incubations L8 cells (ATCC, U.S.A.) were grown and differentiated into myotubes according to previous established method

ABSTRACT MODELLING RISK SPILLOVERS IN ENVIRONMENTAL FINANCE

Environmental issues have become increasingly important in economic research and policy for sustainable development. Such issues are tracked by the Dow Jones Sustainable Indexes (DJSI) through financial market indexes that are derived from the Dow Jones Global Indexes. The environmental sustainability activities of firms are assessed using criteria in three areas, namely economic, environmental and social. Risk (or uncertainty) is analysed empirically through the use of conditional volatility models of investment in sustainabilitydriven firms that are selected through the DJSI. This paper analyses the trends and volatility in DJSI indexes using daily data from 31 December 1998 to 1 March 2004. The conditional variance of the DJSI indexes is analysed using three multivariate GARCH models, namely CCC, VARMA-GARCH and VARMA-AGARCH. These models are able to capture the dynamics in the conditional variance and the existence of risk spillovers in the DJSI indexes. 1

Proceedings of the 2005 International Conference on Simulation and Modelling

Most documented Bayesian network (BN) applications have been built through knowledge elicitation from domain experts (DEs). The difficulties involved have led to growing interest in machine learning of BNs from data. There is a further need for combining what can be learned from the data with what can be elicited from DEs. In previous work, we proposed a detailed methodology for this combination, specifically for the parameters of a BN. In this paper, we illustrate the techniques using a case study of a