Platelet Hyperreactivity in Diabetes: Focus on GPVI Signaling-Are Useful Drugs Already Available?

Mechano-Redox Control of Integrins in Thromboinflammation

Significance: How mechanical forces and biochemical cues are coupled remains a miracle for many biological processes. Integrins, well-known adhesion receptors, sense changes in mechanical forces and reduction-oxidation reactions (redox) in their environment to mediate their adhesive function. The coupling of mechanical and redox function is a new area of investigation. Disturbance of normal mechanical forces and the redox balance occurs in thromboinflammatory conditions; atherosclerotic plaques create changes to the mechanical forces in the circulation. Diabetes induces redox changes in the circulation by the production of reactive oxygen species and vascular inflammation. Recent Advances: Integrins sense changes in the blood flow shear stress at the level of focal adhesions and respond to flow and traction forces by increased signaling. Talin, the integrin-actin linker, is a traction force sensor and adaptor. Oxidation and reduction of integrin disulfide bonds regulate their adhesion. A conserved disulfide bond in integrin αlpha IIb beta 3 (αIIbβ3) is directly reduced by the thiol oxidoreductase endoplasmic reticulum protein 5 (ERp5) under shear stress. Critical Issues: The coordination of mechano-redox events between the extracellular and intracellular compartments is an active area of investigation. Another fundamental issue is to determine the spatiotemporal arrangement of key regulators of integrins' mechanical and redox interactions. How thromboinflammatory conditions lead to mechanoredox uncoupling is relatively unexplored. Future Directions: Integrated approaches, involving disulfide bond biochemistry, microfluidic assays, and dynamic force spectroscopy, will aid in showing that cell adhesion constitutes a crossroad of mechano- and redox biology, within the same molecule, the integrin. Antioxid. Redox Signal. 37, 1072-1093.

Spontaneous Platelet Aggregation in Blood Is Mediated by FcγRIIA Stimulation of Bruton’s Tyrosine Kinase

High platelet reactivity leading to spontaneous platelet aggregation (SPA) is a hallmark of cardiovascular diseases; however, the mechanism underlying SPA remains obscure. Platelet aggregation in stirred hirudin-anticoagulated blood was measured by multiple electrode aggregometry (MEA) for 10 min. SPA started after a delay of 2–3 min. In our cohort of healthy blood donors (n = 118), nine donors (8%) with high SPA (>250 AU*min) were detected. Pre-incubation of blood with two different antibodies against the platelet Fc-receptor (anti-FcγRIIA, CD32a) significantly reduced high SPA by 86%. High but not normal SPA was dose-dependently and significantly reduced by blocking Fc of human IgG with a specific antibody. SPA was completely abrogated by blood pre-incubation with the reversible Btk-inhibitor (BTKi) fenebrutinib (50 nM), and 3 h after intake of the irreversible BTKi ibrutinib (280 mg) by healthy volunteers. Increased SPA was associated with higher platelet GPVI reactivity. Anti-platelet factor 4 (PF4)/polyanion IgG complexes were excluded as activators of the platelet Fc-receptor. Our results indicate that high SPA in blood is due to platelet FcγRIIA stimulation by unidentified IgG complexes and mediated by Btk activation. The relevance of our findings for SPA as possible risk factor of cardiovascular diseases and pathogenic factor contributing to certain autoimmune diseases is discussed.

Clinical Outcome between Ticagrelor versus Clopidogrel in Patients with Acute Coronary Syndrome and Diabetes

BACKGROUND

The increased thrombotic risk in patients with acute coronary syndrome (ACS) and diabetes highlights the need for adequate antithrombotic protection. We aimed to compare the 6-month clinical outcomes between ticagrelor and clopidogrel in patients with ACS and diabetes.

METHODS AND RESULTS

The study was a single-center, prospective, randomized, open-label, blinded endpoint, and controlled registry trial. A total of 270 ACS patients with diabetes were randomly assigned in a 1 : 1 ratio to either the ticagrelor group or the clopidogrel group. Follow-up was performed for 6 months, and the data on efficacy outcomes and bleeding events were collected. At 6 months, complete follow-up data were available for 266 (98.5%) of 270 patients, and 4 were lost to follow-up. There was no significant difference in the survival rate of the effective endpoints between the ticagrelor group (n = 133) and the clopidogrel group (n = 133) (HR 0.83, 95% CI 0.44-1.56, p = 0.561), but the incidence of bleeding events in the ticagrelor group was higher than that in the clopidogrel group (HR 1.76, 95% CI 1.00-3.10, p = 0.049).

CONCLUSION

Ticagrelor did not improve the composite of nonfatal MI, target vessel revascularization, rehospitalization, stroke, and death from any cause; however, it significantly increased the incidence of bleeding events defined by the Bleeding Academic Research Consortium (BARC) criteria in Chinese patients with ACS and diabetes during the 6-month follow-up compared with clopidogrel.

Diabetes mellitus is independently associated with early stent thrombosis in patients undergoing drug eluting stent implantation: Analysis from the Victorian cardiac outcomes registry

BACKGROUND

Diabetes mellitus (DM) is a predictor of restenosis and late stent thrombosis (ST) in patients undergoing percutaneous coronary intervention (PCI) with drug-eluting-stents (DES). Real-world data on rates of early ST is lacking. We compared clinical outcomes of patients with and without DM from the Victorian cardiac outcomes registry.

METHODS

Consecutive patients undergoing PCI with DES were analyzed with primary outcome being ST at 30-days. Secondary outcomes including major adverse cardiovascular events (MACE) and all-cause mortality.

RESULTS

Of 43,209 patients included, 9730 (22.5%) had DM. At 30 days, DM was independently associated with higher rates of early ST (0.7% vs. 0.5%) OR 1.41 (95% confidence interval; 1.05-1.87, p = 0.02), MACE (4.1% vs. 3.5%, p = 0.004) and mortality (1.9% vs. 1.5%, p = 0.01). Increased risk was not simply due to treatment. Patients with DM requiring insulin were equally affected in regard to MACE (4.7% vs. 3.9%, p = 0.069) and mortality (1.9%, vs. 1.8%, p = 0.746). On National Death Index linkage, patients with DM had increased all-cause mortality over five-year follow-up (OR 1.69 CI 1.55-1.83, p = < 0.001).

CONCLUSION

In this large real-world-registry, DM was an independent predictor of early ST, MACE and mortality at 30 days. These data suggest additional therapeutic strategies are required to reduce the risk of early complications in patients with DM undergoing PCI with DES.

Tyrosine Kinase Inhibitor Sunitinib Delays Platelet-Induced Coagulation: Additive Effects of Aspirin

BACKGROUND

 Sunitinib is a multitarget tyrosine kinase inhibitor (TKI) used for cancer treatment. In platelets, sunitinib affects collagen-induced activation under noncoagulating conditions. We investigated (1) the effects of sunitinib on thrombus formation induced by other TK-dependent receptors, and (2) the effects under coagulating conditions. Cardiovascular disease is a comorbidity in cancer patients, resulting in possible aspirin treatment. Sunitinib and aspirin are associated with increased bleeding risk, and therefore we also investigated (3) the synergistic effects of these compounds on thrombus and fibrin formation.

METHODS

 Blood or isolated platelets from healthy volunteers or cancer patients were incubated with sunitinib and/or aspirin or vehicle. Platelet activation was determined by TK phosphorylation, flow cytometry, changes in [Ca²⁺]_i, aggregometry, and whole blood perfusion over multiple surfaces, including collagen with(out) tissue factor (TF) was performed.

RESULTS

 Sunitinib reduced thrombus formation and phosphatidylserine (PS) exposure under flow on collagen type I and III. Also, sunitinib inhibited glycoprotein VI-induced TK phosphorylation and Ca²⁺ elevation. Upon TF-triggered coagulation, sunitinib decreased PS exposure and fibrin formation. In blood from cancer patients more pronounced effects of sunitinib were observed in lung and pancreatic as compared to neuroglioblastoma and other cancer types. Compared to sunitinib alone, sunitinib plus aspirin further reduced platelet aggregation, thrombus formation, and PS exposure on collagen under flow with(out) coagulation.

CONCLUSION

 Sunitinib suppresses collagen-induced procoagulant activity and delays fibrin formation, which was aggravated by aspirin. Therefore, we urge for awareness of the combined antiplatelet effects of TKIs with aspirin, as this may result in increased risk of bleeding.

Impaired intestinal barrier function in type 2 diabetic patients measured by serum LPS, Zonulin, and IFABP

INTRODUCTION

The epithelial tight junctions of intestine were impaired in murine model of type 2 diabetes mellitus (T2DM). The aim of this work was to investigate the alteration of intestinal barrier in T2DM patients.

METHODS

90 patients with T2DM and 28 healthy controls were recruited. Serum lipopolysaccharide (LPS), Zonulin, and intestinal fatty acid binding protein (IFABP) were measured by ELISA, based on which a derived permeability risk score (PRS) was calculated. Subgroup analyses were conducted based on the glycemic control (HbA1c < 7%, or HbA1c ≥ 7%), the amount of chronic diabetic complications, and the use of aspirin at the time.

RESULTS

Serum LPS, Zonulin, and IFABP, and PRS of T2DM group were significantly higher than those of the control group (p < 0.05 for all). Serum LPS and PRS was higher in T2DM patients with poor glycemic control (both p < 0.05). Patients with more chronic complications of diabetes had higher serum LPS and IFABP, and PRS (all p < 0.05). No differences were found in these serum markers between T2DM patients being treated with aspirin or not.

CONCLUSIONS

Intestinal barrier function was impaired in T2DM patients. Poor glycemic control and more chronic complications of diabetes were associated with worse intestinal barrier function. Treatment with aspirin did not aggravate the impairment of intestinal barrier in T2DM patients.

Oxidative Stress and Inflammation in Renal and Cardiovascular Complications of Diabetes

Simple Summary

The progressive nature of type 2 diabetes mellitus (T2DM) leads to micro- and macro-vascular complications, including renal and cardiovascular disease. These alone, or in combination, are a major cause of premature morbidity and mortality in diabetic patients. Despite advances in glucose lowering treatments, these diabetic complications are still inadequately prevented or reversed. This ongoing cardiovascular–renal burden in diabetes poses a heavy cost on the health care system. Therefore, there is an urgent need to develop more effective treatments. In this review, we discuss how oxidative stress and inflammation induce and perpetuate the renal and cardiovascular complications of diabetes. It is particularly important to understand these driving mechanisms in order to elucidate pharmacological targets and mechanism-based future drug therapies.

Abstract

Oxidative stress and inflammation are considered major drivers in the pathogenesis of diabetic complications, including renal and cardiovascular disease. A symbiotic relationship also appears to exist between oxidative stress and inflammation. Several emerging therapies target these crucial pathways, to alleviate the burden of the aforementioned diseases. Oxidative stress refers to an imbalance between reactive oxygen species (ROS) and antioxidant defenses, a pathological state which not only leads to direct cellular damage but also an inflammatory cascade that further perpetuates tissue injury. Emerging therapeutic strategies tackle these pathways in a variety of ways, from increasing antioxidant defenses (antioxidants and Nrf2 activators) to reducing ROS production (NADPH oxidase inhibitors and XO inhibitors) or inhibiting the associated inflammatory pathways (NLRP3 inflammasome inhibitors, lipoxins, GLP-1 receptor agonists, and AT-1 receptor antagonists). This review summarizes the mechanisms by which oxidative stress and inflammation contribute to and perpetuate diabetes associated renal and cardiovascular disease along with the therapeutic strategies which target these pathways to provide reno and cardiovascular protection in the setting of diabetes.

Novel antiplatelet strategies targeting GPVI, CLEC-2 and tyrosine kinases

Antiplatelet medications comprise the cornerstone of treatment for diseases that involve arterial thrombosis, including acute coronary syndromes (ACS), stroke and peripheral arterial disease. However, antiplatelet medications may cause bleeding and, furthermore, thrombotic events may still recur despite treatment. The interaction of collagen with GPVI receptors on the surface of platelets has been identified as one of the major players in the pathophysiology of arterial thrombosis that occurs following atherosclerotic plaque rupture. Promisingly, GPVI deficiency in humans appears to have a minimal impact on bleeding. These findings together suggest that targeting platelet GPVI may provide a novel treatment strategy that provides additional antithrombotic efficacy with minimal disruption of normal hemostasis compared to conventional antiplatelet medications. CLEC-2 is gaining interest as a therapeutic target for a variety of thrombo-inflammatory disorders including deep vein thrombosis (DVT) with treatment also predicted to cause minimal disruption to hemostasis. GPVI and CLEC-2 signal through Src, Syk and Tec family tyrosine kinases, providing additional strategies for inhibiting both receptors. In this review, we summarize the evidence regarding GPVI and CLEC-2 and strategies for inhibiting these receptors to inhibit platelet recruitment and activation in thrombotic diseases.

Polymorphisms in GP6, PEAR1A, MRVI1, PIK3CG, JMJD1C, and SHH Genes in Patients with Unstable Angina

INTRODUCTION

Coronary artery disease (CAD) is a significant public health problem because it is one of the major causes of death worldwide. Several studies have investigated the associations between CAD and polymorphisms in genes connected with platelet aggregation and the risk of venous thromboembolism.

AIM

In this study, we examined the associations between polymorphisms in GP6 (rs1671152), PEAR1A (rs12566888), MRVI1 (rs7940646), PIK3CG (rs342286), JMJD1C (rs10761741), SHH (rs2363910), and CAD in the form of unstable angina as well as selected clinical and biochemical parameters. The study enrolled 246 patients with diagnosed unstable angina and 189 healthy controls.

RESULTS

There were no significant differences in the distribution of the studied polymorphisms between the patients with unstable angina and the controls. In patients with the GP6 rs1671152 GG genotype, we observed increased BMI values and an increased frequency of type 2 diabetes diagnosis.

CONCLUSIONS

The results of this study suggest a lack of association between GP6 (rs1671152), PEAR1A (rs12566888), MRVI1 (rs7940646), PIK3CG (rs342286), JMJD1C (rs10761741), SHH (rs2363910), and unstable angina. The results indicate an association between GP6 (rs1671152) and type 2 diabetes.

Progress toward a Glycoprotein VI Modulator for the Treatment of Thrombosis

Pathogenic thrombus formation accounts for the etiology of many serious conditions including myocardial infarction, stroke, deep vein thrombosis, and pulmonary embolism. Despite the development of numerous anticoagulants and antiplatelet agents, the mortality rate associated with these diseases remains high. In recent years, however, significant epidemiological evidence and clinical models have emerged to suggest that modulation of the glycoprotein VI (GPVI) platelet receptor could be harnessed as a novel antiplatelet strategy. As such, many peptidic agents have been described in the past decade, while more recent efforts have focused on the development of small molecule modulators. Herein the rationale for targeting GPVI is summarized and the published GPVI modulators are reviewed, with particular focus on small molecules. A qualitative pharmacophore hypothesis for small molecule ligands at GPVI is also presented.

Impact of diabetes mellitus on coagulation function before and after off-pump coronary artery bypass grafting

Background

This study aims to explore the influence of off-pump coronary artery bypass grafting (OPCABG) on coagulation function and the effects of diabetes on coagulation function during OPCABG.

Methods

Patients who met the inclusion and exclusion criteria were divided into two groups: diabetes mellitus (DM) and non-diabetes mellitus (NDM) groups. Thromboelastography (TEG) was tested at the following time points: T0, five days after aspirin and clopidogrel therapy, and before OPCABG; T1, returning to care unit after OPCABG; T2, 5 days after aspirin and clopidogrel therapy, and after OPCABG.

Results

A total of 56 patients were involved. There were no deaths, or no early postoperative thrombotic events and abnormal bleeding after OPCABG. Intra-group comparison: Compared with T0, the R and K value decreased, while the α angle and MA value increased at T1 and T2, in both groups (P<0.05). A significantly statistical difference was found in the multiple comparison at T0, T1 and T2 (P<0.05). The results are as follows: the R value decreased at T1 and increased at T2, but the value remained less than that at T0. After the OPCABG, the K value gradually decreased, while the MA value and α angle gradually increased. Comparison between groups: T1: the R values were lower in the DM group, when compared to the NDM group (t=3.611, P=0.001). The differences in the MA, K and α angle were not statistically significant. T0 and T2: there were no statistically difference in the R, MA, K, α angle and LY30 between the two groups (P>0.05).

Conclusions

The coagulation function of patients was at a hypercoagulable state at the early stage after OPCABG. The coagulation function was affected by diabetes at the day of OPCABG. However, there was no statistical difference after 5 days of aspirin and clopidogrel therapy following OPCABG.

Salvianolic acid a inhibits platelet activation and aggregation in patients with type 2 diabetes mellitus

Background

Platelets in patients with type 2 diabetes mellitus (DM2) are characterized by increased activation and aggregation, which tends to be associated with a high morbidity and mortality due to cardiovascular disease (CVD). Moreover, a large proportion of DM2 patients show an inadequate response to standard antiplatelet treatments, contributing to recurrent cardiovascular events. In our previous study, we indicated that Salvianolic acid A (SAA) presents an antiplatelet effect in healthy volunteers. However, whether it can inhibit “activated platelets” with a pathologic status has not been explored. Therefore, this study was designed to investigate the antiplatelet effect of SAA and its diabetic complication-related difference in DM2.

Methods

Forty patients diagnosed with DM2 from January 2018 to April 2018 were recruited. Fibrinogen-binding (PAC-1) and P-selectin (CD62p) flow cytometry reagents were measured under resting and stimulated conditions by flow cytometry, while agonist-induced platelet aggregation was conducted by light transmission aggregometry. Before all these measurements were conducted, all platelet samples were preincubated with a vehicle or SAA for 10 min. Additionally, the diabetic complication-related difference in the antiplatelet effect of SAA was further studied in enrolled patients.

Results

The expressions of PAC-1 and CD62p were elevated in DM2, as well as the maximal platelet aggregation. In addition, SAA decreased the expressions of PAC-1 and CD62p, which were enhanced by ADP and thrombin (all P < 0.01). It also reduced the platelet aggregation induced by ADP (P < 0.001) and thrombin (P < 0.05). Comparing the antiplatelet effect of SAA on DM2, with and without diabetic complications, no statistically significant difference was found (all P > 0.05).

Conclusions

The present study demonstrated that SAA can inhibit platelet activation and aggregation in patients with DM2, and the inhibition did not abate for the existence of diabetic complications.

Platelets as Potent Signaling Entities in Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is a multifactorial disease with a dysregulated circulating inflammatory molecule tendency. T2DM is closely associated with systemic inflammation, endothelial dysfunction, cardiovascular risk, and increased clotting susceptibility. Platelets have fundamental roles in the development and propagation of inflammation and cardiovascular risk. They signal through membrane receptors, resulting in (hyper)activation and release of inflammatory molecules from platelet compartments. This review highlights how circulating inflammatory molecules, acting as platelet receptor ligands, interact with platelets, causing platelets to be potent drivers of systemic inflammation. We conclude by suggesting that focused platelet research in T2DM is an important avenue to pursue to identify novel therapeutic targets, and that platelets could be used as cellular activity sensors themselves.

Progress in the development of antiplatelet agents: Focus on the targeted molecular pathway from bench to clinic

Antiplatelet drugs serve as a first-line antithrombotic therapy for the management of acute ischemic events and the prevention of secondary complications in vascular diseases. Numerous antiplatelet therapies have been developed; however, currently available agents are still associated with inadequate efficacy, risk of bleeding, and variability in individual response. Understanding the mechanisms of platelet involvement in thrombosis and the clinical development process of antiplatelet agents is critical for the discovery of novel agents. The functions of platelets in thrombosis are regulated by two major mechanisms: the interaction between surface receptors and their ligands, and the downstream intracellular signaling pathways. Recently, most of the progress made in antiplatelet drug development has been achieved with P2Y receptor antagonists. Additionally, the usage of GP IIb/IIIa receptor antagonists has decreased, because it is associated with a higher risk of bleeding and thrombocytopenia. Agents targeting other platelet surface receptors such as PARs, TP receptor, EP3 receptor, GPIb-IX-V receptor, P-selectin, as well as intracellular signaling factors, such as PI3Kβ, have been evaluated in an attempt to develop the next generation of antiplatelet drugs, reduce or eliminate interpatient variability of drug efficacy and significantly lower the risk of drug-induced bleeding. The aim of this review is to describe the pathways of platelet activation in thrombosis, and summarize the development process of antiplatelet agents, as well as the preclinical and clinical evaluations performed on these agents.

Autologous platelet-rich plasma for healing chronic venous leg ulcers: Clinical efficacy and potential mechanisms

The overall quality of evidence of autologous platelet-rich plasma (PRP) for treating chronic wounds remains low. While further well-designed clinical studies are clearly required to convincingly demonstrate the efficacy of autologous PRP in improved healing of venous leg ulcers (VLUs) and other chronic wounds, there is also an increasing need to better define the underlying mechanisms of action and whether positive outcomes can be predicted based on the analysis of PRP. This brief review will discuss the current understanding of autologous PRP in VLUs and whether molecular evaluation of PRP at the time of collection could potentially be informative to clinical outcomes. Benefits of the autologous PRP treatment strategy include that PRP is easily accessible and is relatively inexpensive and safe. Better understanding of the mechanisms involved could improve treatment, enable supplementation, and/or lead to gains in product development. Analysis of PRP could also add value to future clinical trials on efficacy and potentially personalised treatment regimens.

Forms of extracellular mitochondria and their impact in health

Mitochondria play an important role as an intracellular energy plant and signaling organelle. However, mitochondria also exist outside cells where they could mediate cell-to-cell communication, repair and serve as an activator of the immune response. Their effects depend on the mitochondrial state or the form in which it is present, either as a whole functional structure as fragments or only as mitochondrial DNA. Herein, we provide evidence of why extracellular mitochondria and their varying forms are considered regenerative factors or pro-inflammatory activators. Understanding these aspects will provide the base of their use in therapy or as a biomarker of disease severity and prognosis.

Early and Late Stent Thrombosis in Patients with Versus Without Diabetes Mellitus Following Percutaneous Coronary Intervention with Drug-Eluting Stents: A Systematic Review and Meta-Analysis

BACKGROUND

Nowadays, drug-eluting stents (DES) are most commonly used compared with bare metal stents (BMS) since the former are associated with significantly lower rates of revascularization following percutaneous coronary intervention (PCI). However, unpredictable in-stent thrombosis is a major concern with DES, especially in patients with diabetes mellitus.

OBJECTIVE

In this analysis, we aimed to systematically compare early and late stent thrombosis in patients with versus without diabetes mellitus following PCI with DES.

METHODS

Studies were included if they were randomized controlled trials or observational studies comparing patients with diabetes mellitus versus those without it following PCI with DES and they reported acute and sub-acute/early and late stent thrombosis among their clinical outcomes. Early stent thrombosis was defined as stent thrombosis that occurred before 30 days and late stent thrombosis was defined as stent thrombosis that occurred after 30 days following PCI. The statistical analysis was carried out by the new version of the RevMan software (version 5.3), and odds ratios (ORs) and 95% confidence intervals (CIs) were considered as the statistical parameters.

RESULTS

A total number of 18,910 patients were included in this analysis comparing early and late stent thrombosis in patients with diabetes mellitus (5123 patients) and in patients without diabetes mellitus (13,787 patients). Both groups of patients had similar rates of early stent thrombosis, with an OR of 1.30 (95% CI 0.89-1.91; P = 0.18, I² = 9%) (4962 patients with diabetes mellitus were compared with 13,392 patients without diabetes mellitus). However, late stent thrombosis was significantly higher in patients with diabetes mellitus, with an OR of 1.95 (95% CI 1.35- 2.81; P = 0.0004, I² = 0%) (5113 patients with diabetes mellitus and 13,775 patients without diabetes mellitus were compared).

CONCLUSIONS

Both patients with and without diabetes mellitus had a similar rate of early stent thrombosis following PCI with DES. However, diabetes mellitus was associated with a significantly higher rate of late stent thrombosis.

Platelet populations and priming in hematological diseases

In healthy subjects and patients with hematological diseases, platelet populations can be distinguished with different response spectra in hemostatic and vascular processes. These populations partly overlap, and are less distinct than those of leukocytes. The platelet heterogeneity is linked to structural properties, and is enforced by inequalities in the environment. Contributing factors are variability between megakaryocytes, platelet ageing, and positive or negative priming of platelets during their time in circulation. Within a hemostatic plug or thrombus, platelet heterogeneity is enhanced by unequal exposure to agonists, with populations of contracted platelets in the thrombus core, discoid platelets at the thrombus surface, patches of ballooned and procoagulant platelets forming thrombin, and coated platelets binding fibrin. Several pathophysiological hematological conditions can positively or negatively prime the responsiveness of platelet populations. As a consequence, in vivo and in vitro markers of platelet activation can differ in thrombotic and hematological disorders.