Comparison between species-specific oligonucleotide tags and biomarkers where the differences are bold and underlined.

<p>Comparison between species-specific oligonucleotide tags and biomarkers where the differences are bold and underlined.</p

The Role of Lateral Tension in Calcium-Induced DPPS Vesicle Rupture

We assess the role of lateral tension in rupturing anionic dipalmitoylphosphatidyserine (DPPS), neutral dipalmitoylphosphatidylcholine (DPPC), and mixed DPPS–DPPC vesicles. Binding of Ca²⁺ is known to have a significant impact on the effective size of DPPS lipids and little effect on the size of DPPC lipids in bilayer structures. In the present work we utilized laser transmission spectroscopy (LTS) to assess the effect of Ca²⁺-induced stress on the stability of the DPPS and DPPC vesicles. The high sensitivity and resolution of LTS has permitted the determination of the size and shape of liposomes in solution. The results indicate a critical size after which DPPS single shell vesicles are no longer stable. Our measurements indicate Ca²⁺ promotes bilayer fusion up to a maximum diameter of ca. 320 nm. These observations are consistent with a straightforward free-energy-based model of vesicle rupture involving lateral tension between lipids regulated by the binding of Ca²⁺. Our results support a critical role of lateral interactions within lipid bilayers for controlling such processes as the formation of supported bilayer membranes and pore formation in vesicle fusion. Using this free energy model we are able to infer a lower bound for the area dilation modulus for DPPS (252 pN/nm) and demonstrate a substantial free energy increase associated with vesicle rupture

Schematic diagram of DNA detection using LTS.

<p>Schematic diagram of DNA detection using LTS.</p

Comparison between LTS and DLS results.

<p>The plot shows the particle size distributions obtained for 209 nm carboxylated polystyrene beads in water using: the original table-top LTS apparatus (solid blue line); a transportable LTS based instrument (solid red line); and a commercial DLS based instrument (dash-dot-dot-dot line).</p

A Potent Class of GPR40 Full Agonists Engages the EnteroInsular Axis to Promote Glucose Control in Rodents

<div><p>Type 2 diabetes is characterized by impaired glucose homeostasis due to defects in insulin secretion, insulin resistance and the incretin response. GPR40 (FFAR1 or FFA1) is a G-protein-coupled receptor (GPCR), primarily expressed in insulin-producing pancreatic β-cells and incretin-producing enteroendocrine cells of the small intestine. Several GPR40 agonists, including AMG 837 and TAK-875, have been disclosed, but no GPR40 synthetic agonists have been reported that engage both the insulinogenic and incretinogenic axes. In this report we provide a molecular explanation and describe the discovery of a unique and potent class of GPR40 full agonists that engages the enteroinsular axis to promote dramatic improvement in glucose control in rodents. GPR40 full agonists AM-1638 and AM-6226 stimulate GLP-1 and GIP secretion from intestinal enteroendocrine cells and increase GSIS from pancreatic islets, leading to enhanced glucose control in the high fat fed, streptozotocin treated and NONcNZO10/LtJ mouse models of type 2 diabetes. The improvement in hyperglycemia by AM-1638 was reduced in the presence of the GLP-1 receptor antagonist Ex(9–39)NH₂.</p> </div

Specificity of AM-1638 to GPR40 (FFAR1) <i>in vivo</i> and effect of the GLP-1R antagonist GLP-1(9–39)NH₂.

<p>An OGTT was performed in (A) wild type or (B) GPR40 null mice following a single oral dose of AM-1638 or sitagliptin. Glucose was dosed 1-hr post drug treatment. (C) Glucose AUC during OGTT. (D) GLP-1 secretion following a single oral dose of AM-1638 in wild type or GPR40 null mice. AM-1638 (60 mg/kg) was tested in an IPGTT in the presence or absence of the GLP-1R antagonist GLP-1(9–39)NH₂ (300 µg/kg) as described in the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0046300#s4" target="_blank">Materials and Methods</a> section. (E) Plasma glucose levels (F) Glucose AUC and (G) plasma insulin levels at the indicated timepoints during the experiment. Statistical significance compared to vehicle treatment is denoted by *(p<0.05), **(p<0.01), ***(p<0.001) and ****(p<0.0001), as determined by one-way or two-way ANOVA, and are color-coded to the treatment in the figure legends.</p

<i>In vitro</i> characterization of AM-1638 and AM-6226 and comparison to AMG 837.

<p>(A) Aequorin Ca²⁺ assay comparing AMG 837 to natural fatty acid ligands DHA, α-LNN and arachidonic acid. (B) Chemical structures of the key compounds synthesized during the medicinal chemistry effort that led to the discovery of AM-1638 and AM-6226. (C) Aequorin Ca²⁺ flux with key synthetic agonists and fatty acids. (D) Inositol phosphate assay with key synthetic agonists and fatty acids. (E–G) Plasmid titration experiments to examine agonist activity under conditions with reduced receptor levels, where either 5000 ng (E), 500 ng (F) or 50 ng (G) of GPR40 (FFAR1) expression plasmid was co-transfected with aequorin expression plasmids into CHO cells. (H) Competition binding experiment with ³H-AMG 837. (I) Competition binding experiment with ³H-AM-1638.</p

AMG 837 Potentiates Insulin Secretion from Islets.

<p>Islets were isolated from mice and the activity of AMG 837 on insulin secretion was determined. (A) The dose response relationship of AMG 837 and insulin secretion on mouse islets at 16.7 mM glucose was evaluated. (B) In order to determine whether the activity of AMG 837 was GPR40/FFA1 dependent, islets were isolated from GPR40 null mice (<i>gpr40^−/−</i>). AMG 837 potentiated glucose stimulated insulin secretion from wild type islets (black bar), but not <i>gpr40^−/−</i> islets (blue bar). (C) Glucose dependence of AMG 837 on glucose stimulated insulin secretion was determined by incubating islets in buffer containing either 0.1% DMSO (black bar) or 1 µM AMG 837 in 0.1% DMSO (blue bar) in the presence of increasing concentrations of glucose. Statistical significance is denoted by * (p<0.5), ** (p<0.01) and *** (p<0.001) as determined by one-way or two-way ANOVA.</p

Improvement in glucose tolerance and potentiation of insulin secretion in Sprague-Dawley rats treated with AMG 837.

<p>8-week old Sprague-Dawley rats were treated with a single bolus of AMG 837 (at 0.03, 0.1 and 0.3 mg/kg, n = 6/group) by oral gavage 30-minutes prior to an intraperitoneal glucose challenge at t = 0 minutes. (A) Blood glucose measurements were taken during prior to and following glucose challenge. Black circle = vehicle, blue triangle = 0.03 mg/kg AMG 837, green diamond = 0.1 mg/kg AMG 837 and purple square = 0.3 mg/kg AMG 837 (B) The glucose AUC (from −30 to 120 minutes) during the course of the experiments were calculated. (C) Plasma insulin levels were measured using ELISA. Black circle = vehicle, blue triangle = 0.03 mg/kg AMG 837, green diamond = 0.1 mg/kg AMG 837 and purple square = 0.3 mg/kg AMG 837 (D–D) Two successive glucose challenges were conducted in Sprague-Dawley rats following a single oral dose of vehicle (n = 4, black circle) or AMG 837 at 0.3 mg/kg (n = 4, purple diamond). AMG 837 was dosed at −30 minutes, and glucose was administered by <i>ip</i> injection at 0 and 180 minutes. Blood glucose (D), calculated glucose AUC (from 0–60 minutes following glucose challenge (E, black bars = vehicle, purple bars = 0.3 mg/kg AMG 837) and plasma insulin (F) were determined. Statistical significance is denoted by * (p<0.5), ** (p<0.01) and *** (p<0.001) as determined by one-way or two-way ANOVA.</p

Efficacy of AMG 837 in Zucker fatty (<i>fa/fa</i>) rats following a single dose.

<p>8-week old Zucker fatty rats were administered a single bolus of AMG 837 (at 0.3, 1 and 3 mg/kg, n = 6/group) by oral gavage 30-minutes prior to an intraperitoneal glucose challenge at t = 0 minutes. (A) Blood glucose during the IPGTT (black circle = vehicle, blue triangle = 0.3 mg/kg AMG 837, green diamond = 1 mg/kg AMG 837 and purple square = 3 mg/kg AMG 837) (B) Glucose AUC (from −30 to 120 minutes) during the IPGTT. (C) Plasma insulin levels during the IPGTT (black circle = vehicle, blue triangle = 0.3 mg/kg AMG 837, green diamond = 1 mg/kg AMG 837 and purple square = 3 mg/kg AMG 837). Statistical significance compared to vehicle treated animals is denoted by * (p<0.5), ** (p<0.01), *** (p<0.001) and **** (p<0.001) as determined by one-way or two-way ANOVA and colors match the corresponding groups in the figure legend.</p