Insulin-releasing and metabolic effects of small molecule GLP-1 receptor agonist 6,7-dichloro-2-methylsulfonyl-3-N-tert-butylaminoquinoxaline

Much recent attention has focused on the GLP-1 receptor as a potential target for antidiabetic drugs. Enzyme resistant GLP-1 mimetics such as exenatide are now employed for the treatment of type 2 diabetes, but must be administered by injection. The present study has examined and compared the in vitro and in vivo metabolic actions of a small molecule GLP-1 receptor agonist 6,7-dichloro-2-methylsulfonyl-3-N-tert-butylaminoquinoxaline (DMB), with native GLP-1, exenatide and liraglutide. DMB significantly stimulated in vitro insulin secretion from BRIN-BD11 cells but with decreased molar potency compared to native GLP-1 or related mimetics. Administration of DMB in combination with glucose to mice significantly (P

Platelet 12-lipoxygenase activation via glycoprotein VI - Involvement of multiple signaling pathways in agonist control of H(P)ETE synthesis

Lipoxygenases (LOX) contribute to vascular disease and inflammation through generation of bioactive lipids, including 12-hydro(pero)xyeicosatetraenoic acid (12-H(P)ETE). The physiological mechanisms that acutely control LOX product generation in mammalian cells are uncharacterized. Human platelets that contain a 12-LOX isoform (p12-LOX) were used to define pathways that activate H( P) ETE synthesis in the vasculature. Collagen and collagen-related peptide (CRP) (1 to 10 mug/mL) acutely induced platelet 12-H(P)ETE synthesis. This implicated the collagen receptor glycoprotein VI ( GPVI), which signals via the immunoreceptor-based activatory motif (ITAM)-containing FcRgamma chain. Conversely, thrombin only activated at high concentrations (> 0.2 U/mL), whereas U46619 and ADP alone were ineffective. Collagen or CRP-stimulated 12-H( P) ETE generation was inhibited by staurosporine, PP2, wortmannin, BAPTA/AM, EGTA, and L-655238, implicating src-tyrosine kinases, PI3-kinase, Ca2+ mobilization, and p12-LOX translocation. In contrast, protein kinase C (PKC) inhibition potentiated 12-H( P) ETE generation. Finally, activation of the immunoreceptor tyrosine-based inhibitory motif (ITIM)-containing platelet endothelial cell adhesion molecule (PECAM-1) inhibited p12-LOX product generation. This study characterizes a receptor-dependent pathway for 12-H(P) ETE synthesis via the collagen receptor GPVI, which is negatively regulated by PECAM-1 and PKC, and demonstrates a novel link between immune receptor signaling and lipid mediator generation in the vasculature.

EFFECTIVE LABORATORY MONITORING FOR THE ABUSE OF THE BETA-AGONIST CLENBUTEROL IN CATTLE

The use of the beta-agonist clenbuterol (CBL) as a growth promoter has been outlawed in European meat production. The detection of its illegal use is dependent on CBL residues persisting in animal tissues for longer than the withdrawal times given by abusers. A comparison of urine, bile and liver matrices indicated that analysis of the liver offered the best possibility for CBL detection. However, an experimental study showed that CBL detection following withdrawal could be further extended (up to 56 d) if the retina was used as the target tissue. Analysis of 703 retina and liver samples from cattle suspected of CBL medication revealed that 96 cattle had CBL residues present in their retinas, only 46 of these were liver positive. There were no instances of liver CBL residues being detected without the associated retina also being positive.

RESIDUES OF THE BETA-AGONIST CLENBUTEROL IN TISSUES OF MEDICATED FARM-ANIMALS

Reports of the illegal use of clenbuterol as a growth promotant prompted the development of a competitive enzyme immunoassay for this drug. This procedure was utilized to study the elimination of clenbuterol from tissues in sheep medicated with both therapeutic and growth-promoting doses of the drug. The results indicated that prior to removal of medication clenbuterol was widely distributed throughout the animal tissues. However as the withdrawal periods increased fluid targets such as urine and bile became less effective at detecting clenbuterol usage. At both therapeutic and growth-enhancing concentrations of clenbuterol liver samples remained positive up to the maximum withdrawal time given in this experiment (15 days). Concentrations of clenbuterol likely to cause food poisoning (> 100 ng/g) were only detected in liver samples taken prior to the removal of medication. The highest recorded concentration of clenbuterol in muscle was 22.5 ng/g.

Effect of intravenous beta-2 agonist treatment on clinical outcomes in acute respiratory distress syndrome (BALTI-2): a multicentre, randomised controlled trial

BACKGROUND:
In a previous randomised controlled phase 2 trial, intravenous infusion of salbutamol for up to 7 days in patients with acute respiratory distress syndrome (ARDS) reduced extravascular lung water and plateau airway pressure. We assessed the effects of this intervention on mortality in patients with ARDS.
METHODS:
We did a multicentre, placebo-controlled, parallel-group, randomised trial at 46 UK intensive-care units between December, 2006, and March, 2010. Intubated and mechanically ventilated patients (aged =16 years) within 72 h of ARDS onset were randomly assigned to receive either salbutamol (15 µg/kg ideal bodyweight per h) or placebo for up to 7 days. Randomisation was done by a central telephone or web-based randomisation service with minmisation by centre, pressure of arterial oxygen to fractional inspired oxygen concentration (PaO(2)/F(I)O(2)) ratio, and age. All participants, caregivers, and investigators were masked to group allocation. The primary outcome was death within 28 days of randomisation. Analysis was by intention-to-treat. This trial is registered, ISRCTN38366450 and EudraCT number 2006-002647-86.
FINDINGS:
We randomly assigned 162 patients to the salbutamol group and 164 to the placebo group. One patient in each group withdrew consent. Recruitment was stopped after the second interim analysis because of safety concerns. Salbutamol increased 28-day mortality (55 [34%] of 161 patients died in the salbutamol group vs 38 (23%) of 163 in the placebo group; risk ratio [RR] 1·47, 95% CI 1·03-2·08).
INTERPRETATION:
Treatment with intravenous salbutamol early in the course of ARDS was poorly tolerated. Treatment is unlikely to be beneficial, and could worsen outcomes. Routine use of ß-2 agonist treatment in ventilated patients with this disorder cannot be recommended.

Bidirectional, iterative approach to the structural delineation of the functional "Chemoprint" in GPR40 for agonist recognition

GPR40, free fatty acid receptor 1 (FFAR1), is a member of the GPCR superfamily and a possible target for the treatment of type 2 diabetes. In this work, we conducted a bidirectional iterative investigation, including computational modeling and site-directed mutagenesis, aimed at delineating amino acid residues forming the functional "chemoprint" of GPR40 for agonist recognition. The computational and experimental studies revolved around the recognition of the potent synthetic agonist GW9508. Our experimentally supported model suggested that H137(4.56), R183(5.39), N244(6.55), and R258(7.35) are directly involved in interactions with the ligand. We have proposed a polarized NH-pi interaction between H137(4.56) and GW9508 as one of the contributing forces leading to the high potency of GW9508. The modeling approach presented in this work provides a general strategy for the exploration of receptor-ligand interactions in G-protein coupled receptors beginning prior to acquisition of experimental data.