Antagonists of the platelet fibrinogen receptor (GP IIb/IIIa receptor) are expected to be a promising new class of antithrombotic agents. The binding of fibrinogen to the fibrinogen receptor depends ...on an Arg-Gly-Asp-Ser (RGDS) tetrapeptide recognition motif. Structural modifications of the RGDS lead have led to the discovery of a non-peptide RGD mimetic GP IIb/IIIa antagonist 44 (S 1197). Compound 44 inhibited, in a dose dependent and reversible manner, human and dog platelet aggregation as well as 125I-fibrinogen binding to ADP-activated human gel filtered platelets and isolated GP IIb/IIIa with K(i) values of 9 nM and 0.17 nM, respectively. A pharmacophore mapping procedure with QXP and a 3D-QSAR analysis applying the GRID/GOLPE methodology yielded a stable, rather predictive model and revealed structural features which are important for binding. Hydrophobic substitutions both at the hydantoin nucleus and at the C-terminus increase the affinity toward the fibrinogen receptor. The crystalline ethyl ester prodrug 48 (HMR 1794) is an orally active antithrombotic agent which is a promising drug candidate for the treatment of thrombotic diseases in humans.
Subclasses of different glycaemic disturbances could explain the variation in characteristics of individuals with type 2 diabetes (T2D). We aimed to examine the association between subgroups based on ...their glucose curves during a five-point mixed-meal tolerance test (MMT) and metabolic traits at baseline and glycaemic deterioration in individuals with T2D.
The study included 787 individuals with newly diagnosed T2D from the Diabetes Research on Patient Stratification (IMI-DIRECT) Study. Latent class trajectory analysis (LCTA) was used to identify distinct glucose curve subgroups during a five-point MMT. Using general linear models, these subgroups were associated with metabolic traits at baseline and after 18 months of follow up, adjusted for potential confounders.
At baseline, we identified three glucose curve subgroups, labelled in order of increasing glucose peak levels as subgroup 1-3. Individuals in subgroup 2 and 3 were more likely to have higher levels of HbA1c, triglycerides and BMI at baseline, compared to those in subgroup 1. At 18 months (n = 651), the beta coefficients (95% CI) for change in HbA1c (mmol/mol) increased across subgroups with 0.37 (-0.18-1.92) for subgroup 2 and 1.88 (-0.08-3.85) for subgroup 3, relative to subgroup 1. The same trend was observed for change in levels of triglycerides and fasting glucose.
Different glycaemic profiles with different metabolic traits and different degrees of subsequent glycaemic deterioration can be identified using data from a frequently sampled mixed-meal tolerance test in individuals with T2D. Subgroups with the highest peaks had greater metabolic risk.
In this study, we report on the characterization of a patient with Glanzmann thrombasthenia (GT). Immunochemical analysis on platelets from the patient showed that the expression of alpha IIb beta 3 ...was only 25% of that in normal healthy controls, suggesting a case of GT. Functional analysis revealed a total lack of fibrinogen binding capacity. Molecular genetic analysis of the full-length cDNA sequences of alpha IIb and beta 3 subunits showed a novel point mutation C621T in alpha IIb cDNA, leading to a missense substitution of threonine for isoleucine at position 176. Coexpression of normal beta 3 and mutant alpha IIb(1176) isoform in mammalian cells showed a marked reduction in the expression of alpha IIb beta 3 heterodimer when compared to the wild-type and a decreased intracellular level of alpha IIb. The T176 I mutation is located in the N-terminal region in the W3:1-2 connecting strand of the beta-propeller. These data suggest that the N-terminal alpha IIb domain plays an important structural role in the formation of heterodimer and that it is also involved in fibrinogen binding.
Aims/hypothesis
The DIRECT (Diabetes Research on Patient Stratification) Study is part of a European Union Framework 7 Innovative Medicines Initiative project, a joint undertaking between four ...industry and 21 academic partners throughout Europe. The Consortium aims to discover and validate biomarkers that: (1) predict the rate of glycaemic deterioration before and after type 2 diabetes onset; (2) predict the response to diabetes therapies; and (3) help stratify type 2 diabetes into clearly definable disease subclasses that can be treated more effectively than without stratification. This paper describes two new prospective cohort studies conducted as part of DIRECT.
Methods
Prediabetic participants (target sample size 2,200–2,700) and patients with newly diagnosed type 2 diabetes (target sample size ~1,000) are undergoing detailed metabolic phenotyping at baseline and 18 months and 36 months later. Abdominal, pancreatic and liver fat is assessed using MRI. Insulin secretion and action are assessed using frequently sampled OGTTs in non-diabetic participants, and frequently sampled mixed-meal tolerance tests in patients with type 2 diabetes. Biosamples include venous blood, faeces, urine and nail clippings, which, among other biochemical analyses, will be characterised at genetic, transcriptomic, metabolomic, proteomic and metagenomic levels. Lifestyle is assessed using high-resolution triaxial accelerometry, 24 h diet record, and food habit questionnaires.
Conclusions/interpretation
DIRECT will yield an unprecedented array of biomaterials and data. This resource, available through managed access to scientists within and outside the Consortium, will facilitate the development of new treatments and therapeutic strategies for the prevention and management of type 2 diabetes.
Peripheral artery disease (PAD) affects >200 million people worldwide and is associated with high mortality and morbidity. We sought to identify genomic variants associated with PAD overall and in ...the contexts of diabetes and smoking status.
We identified genetic variants associated with PAD and then meta-analyzed with published summary statistics from the Million Veterans Program and UK Biobank to replicate their findings. Next, we ran stratified genome-wide association analysis in ever smokers, never smokers, individuals with diabetes, and individuals with no history of diabetes and corresponding interaction analyses, to identify variants that modify the risk of PAD by diabetic or smoking status.
We identified 5 genome-wide significant (
≤5×10
) associations with PAD in 449 548 (N
=12 086) individuals of European ancestry near
) loci (which overlapped previously reported associations). Meta-analysis with variants previously associated with PAD showed that 18 of 19 published variants remained genome-wide significant. In individuals with diabetes, rs116405693 at the
) locus was associated with PAD (odds ratio 95% CI, 1.51 1.32-1.74,
=2.5×10
,
=5.3×10
). Furthermore, in smokers, rs12910984 at the
locus was associated with PAD (odds ratio 95% CI, 1.15 1.11-1.19,
=9.3×10
,
=3.9×10
).
Our analyses confirm the published genetic associations with PAD and identify novel variants that may influence susceptibility to PAD in the context of diabetes or smoking status.
Biomedical research projects involving multiple partners from public and private sectors require coherent internal governance mechanisms to engender good working relationships. The DIRECT project is ...an example of such a venture, funded by the Innovative Medicines Initiative Joint Undertaking (IMI JU). This paper describes the data access policy that was developed within DIRECT to support data access and sharing, via the establishment of a 3-tiered Data Access Committee. The process was intended to allow quick access to data, whilst enabling strong oversight of how data were being accessed and by whom, and any subsequent analyses, to contribute to the overall objectives of the consortium.
SummaryAntagonists of the platelet fibrinogen receptor (GP IIb/IIIa receptor) are expected to be a new promising class of antithrombotic agents. The binding of fibrinogen to the fibrinogen receptor ...depends on an Arg-Gly-Asp-Ser (RGDS) tetrapeptide recognition motif. Structural modifications of the RGDS lead have led to the discovery of a non-peptide RGD mimetic GP IIb/IIIa antagonist20 (S 1197). Compound20 inhibits dose-dependently and reversibly human platelet aggregation. Modeling studies based on structure-activity data revealed the following structural features of the drug as important for receptor binding: the amidino group, the carboxylate group, hydrophobic substitutions at the carboxyl-terminus and at the side chain carrying the positive charge, the carboxyl-terminal NH group of the β-amino acid as a hydrogen bond donor and one oxygen atom of the hydantoin as a hydrogen bond acceptor. The ethyl ester prodrug of20 (S 5740) is an orally active antithrombotic agent which has the potential to be used to treat and prevent thrombotic diseases in humans.
Integrins and other adhesion receptors are essential components for outside‐in and inside‐out signaling through the cell membrane. The platelet glycoprotein IIb‐IIIa (also known as fibrinogen ...receptor or integrin αIIbβ3) is activated by platelet agonists, inhibited by cyclic‐nucleotide‐elevating agents, and is involved in the activation of protein tyrosine kinases including the 125‐kDa focal adhesion kinase (pp125FAK). However, the molecular details of glycoprotein IIb‐IIIa regulation are not well understood. Here we report that in ADP‐activated human platelets cAMP‐ and cGMP‐dependent protein‐kinase‐mediated phosphorylation of the focal adhesion vasodilator‐stimulated phosphoprotein (VASP) at Ser157 correlates well with glycoprotein IIb‐IIIa inhibition. Human platelets contain similar concentrations of glycoprotein IIb‐IIIa complexes (fibrinogen binding sites) and VASP. Using gel‐filtered platelets, cAMP‐elevating agents e.g. prostaglandin E1 and the forskolin analog 6‐(3‐dimethylaminopropionyl)forskolin (NKH 477) caused VASP Ser157 phosphorylation and inhibited glycoprotein IIb‐IIIa activation up to 70–100%. NO‐generating, cGMP‐elevating agents e.g. 3‐morpholinosydnonimine hydrochloride (SIN1) and sodium nitroprusside stimulated VASP Ser157 phosphorylation and inhibited glycoprotein IIb‐IIIa activation up to a maximal extent of 30–50%. The effects of cAMP‐ and cGMP‐elevating agents on VASP phosphorylation and fibrinogen binding were reversible and could be mimicked by membrane‐permeant selective activators of platelet cAMP‐ or cGMP‐dependent protein kinase, respectively. Using threshold concentrations, the nitrovasodilator SIN 1 potentiated the effects of the forskolin analog NKH 477 with respect to inhibition of platelet aggregation, VASP phosphorylation and glycoprotein IIb‐IIIa inhibition. It is proposed that the inhibition of glycoprotein IIb‐IIIa induced by cyclic nucleotide involves cAMP‐and cGMP‐dependent protein‐kinase‐mediated VASP phosphorylation at Ser157.
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