The potent platelet inhibitory effects of S-nitrosated albumin coating of artificial surfaces

High CRP-albumin ratio is associated high thrombus burden in patients with newly diagnosed STEMI

In patients undergoing primary percutaneous coronary intervention (pPCI) due to ST-segment elevation myocardial infarction (STEMI), an increased intracoronary thrombus burden is a strong predictive factor for adverse cardiovascular events. The C-reactive protein (CRP)-serum albumin (SA) ratio (CAR), used as an inflammatory marker, is closely associated with thrombogenicity. In this study, we investigated the relationship between coronary thrombus burden and CAR in patients undergoing pPCI due to newly diagnosed STEMI. A total of 216 patients who underwent pPCI due to STEMI were retrospectively included for the study. Angiographic thrombus burden was assessed according to thrombolysis in myocardial infarction (TIMI) grading, and those with grade 1, 2, 3 were classified as low thrombus burden (n = 120) and those with grade 4, 5 were classified as high thrombus burden (HTB) (n = 96). CAR was calculated as the ratio of CRP to SA. The average age of the patients was 60 ± 9.8, and the male ratio was 61.1. Compared to the LTB group, the HTB group had higher CAR, age, SYNTAX score, baseline cTnT, peak cTnT, CRP, glucose, WBC, and NLR while the LVEF and SA levels were lower (P < .05). Spearman's correlation analysis revealed a significant correlation between thrombus burden and CAR. The multivariable logistic regression analysis revealed that CAR (odds ratio: 10.206; 95% confidence interval: 2.987-34.872, P < .001) was a independent risk factor for HTB. According to the receiver operating characteristic (ROC) analysis, when the cutoff value for CAR was taken as ≥1.105 CAR could predict HTB with a sensitivity of 70.8% and specificity of 67.7%. Our data indicate that CAR an independent risk factor for thrombus burden.

Malnutrition and Risk of Mortality in Ischemic Stroke Patients Treated With Intravenous Thrombolysis

Background and Purpose

Malnutrition is highly prevalent in ischemic stroke patients. We aimed to investigate whether malnutrition indexes may be useful in predicting mortality at 90 days in ischemic stroke patients treated with intravenous thrombolysis.

Methods

We retrospectively analyzed consecutive patients who underwent thrombolytic therapy at three comprehensive stroke centers. Malnutrition was assessed using the controlling nutritional status (CONUT) score, geriatric nutritional risk index (GNRI), and prognostic nutritional index (PNI).

Results

Of 979 patients (mean age, 66.8 years; males, 63.6%) included in this study, 91 (9.3%; 95% confidence interval [CI]: 8.4–10.2%) died at 3-month follow up. According to the CONUT, GNRI, and PNI scores, 9.9, 33.7, and 7.0% of patients were moderately or severely malnourished, respectively; 64.0% were at least mildly malnourished by at least 1 malnutrition index. In the multivariate regression model after adjusting for potential confounders, malnutrition (severe risk versus normal nutritional status) was significantly associated with an increased risk of mortality for CONUT scores (adjusted odds ratio [OR] 16.16, 95%CI, 7.86-67.11; P &lt; 0.001), GNRI scores (adjusted OR 9.82, 4.10-23.51; P &lt; 0.001) and PNI scores (adjusted OR 12.74, 5.56-29.19; P &lt; 0.001). Similar results were found when the malnutrition scores were analyzed as continuous variables. Adding the three malnutrition indexes to models containing conventional risk factors significantly improved risk reclassification for 3-month mortality.

Conclusion

Our study showed that malnutrition may be associated with a higher risk of mortality at 3 months in ischemic stroke after intravenous thrombolysis.

Serum Albumin Levels and Clinical Outcomes Among Ischemic Stroke Patients Treated with Endovascular Thrombectomy

BACKGROUND AND AIMS

Albumin levels have been reported to be associated with all-cause and cardiovascular mortality. The aim of this study was to investigate the association between serum albumin and prognosis of ischemic stroke patients after endovascular thrombectomy (EVT) treatment.

METHODS

Patients with EVT due to large artery occlusion in anterior circulation were selected from ACTUAL (endovascular treatment for acute anterior circulation) ischemic stroke multicenter registry in China. Serum albumin levels were measured within 24 h of admission. The primary outcome was poor functional outcome (modified Rankin scale score of 3-6) at three months. Secondary outcomes were symptomatic intracranial hemorrhage (sICH) and three-month mortality.

RESULTS

A total of 605 patients (mean age, 64.2 years; 59.3% male) were enrolled. Up to three months after stroke, 342 patients (56.5%) developed poor functional outcome. After multivariate adjustment for demographic characteristics, National Institutes of Health stroke score, and other potential confounders, the odds ratio for the lowest tertile of serum albumin levels was 2.43 (95%CI, 1.18-5.01; P=0.046) for poor functional outcome, compared with the highest category. Restricted cubic spline regression demonstrated a linear association between albumin levels and poor functional outcome (P for linearity=0.017). Subgroup analyses further confirmed these results. Similar significant findings were also found in the association of serum albumin with mortality, but not with sICH.

CONCLUSION

Decreased serum albumin levels were independently associated with poor prognosis at 90 days after acute large vessel occlusion stroke in anterior circulation treated with EVT.

Predictive value of fibrinogen-to-albumin ratio in acute coronary syndrome

BACKGROUND

We aimed to investigate the predictive value of the fibrinogen-to-albumin ratio (FAR) regarding the development of major cardiovascular events (MACE) in patients treated with percutaneous coronary intervention (PCI) for acute coronary syndrome (ACS).

METHODS

This was a prospective, observational cohort study that included 261 consecutive patients who were treated with PCI. The patients were grouped according to the occurrence of MACE during the follow-up period.

RESULTS

During follow-up, MACE occurred in 68 (26%) patients. The FAR was independently predictive of MACE (HR: 1.017, 95% CI: 1.010-1.024, p < 0.001). In addition, left ventricular ejection fraction (LVEF) and a diagnosis of ST-segment elevation myocardial infarction (STEMI) were independent predictors of MACE. The area under the curve (AUC) of the multivariable model, including LVEF and diagnosis of STEMI, was 0.707 (95% CI: 0.631-0.782, p < 0.001). When the FAR was added to the multivariable model, the AUC was 0.770 (95% CI: 0.702-0.838, z = 2.820, difference p = 0.0048).

CONCLUSION

The FAR could be used for the prediction of MACE in patients with ACS who have undergone PCI.

Relationship Between the Reciprocal Change in Inflammation-Related Biomarkers (Fibrinogen-to-Albumin and hsCRP-to-Albumin Ratios) and the Presence and Severity of Coronary Slow Flow

Inflammation has been implicated in the pathogenesis of endothelial dysfunction, atherosclerosis, and microvascular coronary dysfunction. In this context, it is thought that fibrinogen, high-sensitive C-reactive protein (hsCRP), and albumin may be associated with the pathogenesis of coronary slow flow (CSF). We aimed to evaluate the ratios of fibrinogen-to-albumin and hsCRP-to-albumin in patients with CSF compared to patients with angiographically normal coronary arteries and stable coronary artery disease (CAD). In all, 65 patients with CSF, 65 patients with newly diagnosed stable CAD, and 65 control participants with angiographically normal coronary arteries were included. The coronary flow rates of all patients were determined by the Thrombolysis in Myocardial Infarction frame count method. Fibrinogen, hsCRP, and albumin levels were analyzed in all patients, and the fibrinogen-to-albumin and hsCRP-to-albumin ratios were calculated. The baseline characteristics of the 3 groups were similar. The plasma albumin level was significantly lower, whereas the fibrinogen and the hsCRP levels were significantly higher, in the CSF and CAD groups compared to the controls. The fibrinogen-to-albumin and hsCRP-to-albumin ratios were significantly higher in both the CSF and the CAD groups compared to the control group. The hsCRP-to-albumin ratio was positively correlated with the mean Thrombolysis in Myocardial Infarction frame count in the whole study population. According to the receiver–operating characteristic analysis, the efficacies of the fibrinogen-to-albumin and hsCRP-to-albumin ratios in predicting CSF were significant. The fibrinogen-to-albumin and hsCRP-to-albumin ratios, which were increased by a reciprocal change, suggest that inflammation may play a role in the pathogenesis of CSF.

The Glasgow prognostic score as a significant predictor of clinical outcomes in patients with acute coronary syndrome

BACKGROUND

Many studies have reported both systemic inflammatory response and malnutrition provide valuable predictions of prognosis in patients with acute coronary syndrome (ACS). This study aims to assess the association between the Glasgow prognostic score (GPS) by combining C-reactive protein and serum albumin concentration, and clinical outcomes in patients with ACS.

METHODS

This retrospective study included patients admitted for ACS between June 2010 and May 2013 in St. Vincent's Hospital, The Catholic University of Korea. In this study, high GPS was defined as a GPS≥1. Primary outcomes were 12-month all-cause and cardiovascular mortality, stroke, stent thrombosis and target vessel revascularization. We used an inverse probability of treatment weighting (IPTW) analysis to adjust for potential confounding covariates and presented event rates with Kaplan-Meier curves.

RESULTS

Total 593 patients were included and follow-up for a median 3.7 years. The patients were classified into two groups: GPS=0 (n=424, 71.5%) and GPS≥1 (n=169, 28.5%). The incidences of primary outcomes were 4% and 8.9% for the GPS=0 and GPS≥1, respectively. The primary outcomes and all-cause mortality difference between the two groups were significantly within 1 month in the Kaplan-Meier curve analysis (log rank p<0.001, log rank p<0.001, respectively). IPTW analysis showed high GPS was independently associated with higher incidence of primary outcomes (HR: 2.206; 95% CI: 1.085-4.486; p=0.029), higher all-cause mortality (HR: 5.963; 95% CI: 2.068-17.190; p<0.001) and higher cardiovascular mortality (HR: 6.122; 95% CI: 1.882-19.914; p=0.003).

CONCLUSIONS

High GPS is independently associated with both total and cardiovascular mortality in patients with ACS. Hence, GPS could be helpful in predicting mortality in ACS patients.

Platelet adhesion on commercially pure titanium plates in vitro I: effects of plasma components and involvement of the von Willebrand factor and fibronectin

Background

Platelet-rich plasma (PRP) is widely used in regenerative dentistry. Furthermore, it is often applied in the pretreatment of titanium implants to improve their surface bioaffinity and initial stability. However, effects of PRP application on implant surface at cellular and molecular levels remain poorly understood. Therefore, we examined platelet adhesion on commercially pure titanium (cp-Ti) plates, with a particular focus on fibrinogen (FGN), von Willebrand factor (vWF), and fibronectin (FN), in the presence or absence of plasma components.

Methods

Citrated blood samples were obtained from six healthy male volunteers, and pure-PRP (P-PRP) and pure platelet suspensions in phosphate-buffered saline (PBS) were prepared. Platelet adhesion on cp-Ti plate surface was evaluated by phalloidin staining and tetrazolium dye assay. Distribution of FGN, vWF, FN, albumin, CD62P, and CD63 was examined by immunocytochemical analysis.

Results

Platelets in PBS suspensions rapidly and time-dependently adhered to cp-Ti plate surface, but this adhesion was substantially disturbed by the presence of plasma components. FGN was most preferably adsorbed regardless of the presence or absence of plasma components, while vWF and FN showed greater accumulation on platelet adhesion area.

Conclusions

Although FGN is rapidly and abundantly adsorbed on cp-Ti plate surface, vWF and FN function as major platelet adhesion molecules in citrated blood samples. After pretreatment with P-PRP, however, platelets adhered to cp-Ti much less efficiently. Therefore, P-PRP pretreatment might not directly contribute to surface functionalization, initial stabilization, and osseointegration of machined or similar types of implants.

Electronic supplementary material

The online version of this article (10.1186/s40729-019-0160-z) contains supplementary material, which is available to authorized users.

Prognostic nutritional index predicts clinical outcome in patients with acute ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention

We aimed to investigate whether the prognostic nutritional index (PNI), a combined nutritional-inflammatory score based on serum albumin levels and lymphocyte count, was associated with mortality in patients with acute ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (pPCI). From September 2011 to November 2014, 309 consecutive patients with STEMI undergoing pPCI were prospectively enrolled. Patients with a combined score of albumin (g/L) + 5 × total lymphocyte count × 10⁹/L ≥ 45 or <45 were assigned a PNI score of 0 or 1, respectively. Of the 309 STEMI patients, 24 (7.74%) died in the hospital, and 15 (4.83%) died during long-term follow-up (median follow-up time, 19.5 [3–36] months). Compared to patients with a PNI of 0, patients with a PNI of 1 had significantly higher in-hospital (14.2% vs. 3.7%; P < 0.001) and long-term follow-up (21.7% vs. 6.9%, P < 0.001) mortality rates. PNI (1/0, HR, 2.414; 95% CI, 1.016 to 5.736; P = 0.046) was a significant independent predictor of mortality in patients with STEMI undergoing pPCI. Moreover, cumulative survival was significantly lower for patients with a PNI of 1 compared to patients with a PNI of 0 (78.3% vs. 93.1%, log-rank P < 0.001). PNI appears useful for the risk stratification of STEMI patients undergoing pPCI.

Modulation of endotoxin-induced cardiopulmonary dysfunction by S-nitroso-albumin

Nitric oxide (NO) is an endogenous vasodilator and modulator of inflammation. During endotoxemia, the beneficial effects of NO are overwhelmed by the inflammatory cascade, resulting in a functional depletion of NO. S-nitroso-albumin ( S-NO-alb) exists as a novel and highly stable NO thiol complex that slowly releases NO into the vascular micro-environment. Using a porcine model, we examined the ability of intravenous S-NO-alb to modulate cardiopulmonary dysfunction characteristic of endotoxemia. Pigs were anesthetized, instrumented for standard cardiopulmonary function measurements, and randomly assigned to receive: (i) albumin + saline; (ii) albumin + LPS; or (iii) S-NO-alb + LPS. Cardiopulmonary parameters were evaluated every 30 min and ex vivo phorbol myristate acetate (PMA)-stimulated superoxide release was serially determined as a marker of in vivo neutrophil priming. Lung myeloperoxidase (MPO) activity was measured as a marker of neutrophil migration into the lung. LPS-induced cardiopulmonary dysfunction was characterized by a sustained elevation in mean pulmonary arterial pressure, pulmonary vascular resistance, and peak intratracheal pressure, as well as a reduction in cardiac index, stroke volume index and PaO2 over 6 h. Pretreatment with S-NO-alb attenuated LPS-induced cardiopulmonary dysfunction without adversely affecting systemic hemodynamics. Moreover, S-NO-alb blunted the LPS-induced hypoxemic response and reduced neutrophil activation. S-NO-alb did not, however, attenuate LPS-induced increases in lung MPO. Our results suggest that S-NO-alb can selectively modulate endotoxin-induced pulmonary dysfunction, attenuate neutrophil priming and block the early mortality (40%) in this model.

Serum albumin levels on admission are associated with angiographic no-reflow after primary percutaneous coronary intervention in patients with ST-segment elevation myocardial infarction

Low serum albumin (SA) levels are associated with increased cardiovascular mortality. We investigated whether baseline SA levels are associated with no-reflow following primary percutaneous coronary intervention (pPCI). A total of 536 patients (aged 60 ± 13 years; 74% men) who underwent pPCI were enrolled. The patients were divided into 2 groups: no-reflow and normal-reflow. No-reflow was defined as thrombolysis in myocardial infarction ≤2 flow. Admission SA levels were significantly lower in the no-reflow group than in the normal-reflow group (3.55 ± 0.44 vs 4.01 ± 0.32 mg/dL, P < .001). Also, high-sensitivity C-reactive protein (hsCRP), creatinine, creatine kinase myocardial band isoenzyme, and troponin T were significantly higher while hemoglobin and left ventricular ejection fraction (LVEF) were significantly lower in the no-reflow group. In multivariate analysis, SA level remained an independent predictor of angiographic no-reflow (odds ratio 0.114, 95% confidence interval 0.032-0.405, P = .001) together with LVEF, hsCRP, and baseline culprit artery patency. Admission SA level was an independent predictor of no-reflow after pPCI.

Tuning the activities and structures of enzymes bound to graphene oxide with a protein glue

Graphene oxide (GO) is being investigated extensively for enzyme and protein binding, but many enzymes bound to GO denature considerably and lose most of their activities. A simple, novel, and efficient approach is described here for improving the structures and activities of enzymes bound to GO such that bound enzymes are nearly as active as those of the corresponding unbound enzymes. Our strategy is to preadsorb highly cationized bovine serum albumin (cBSA) to passivate GO, and cBSA/GO (bGO) served as an excellent platform for enzyme binding. The binding of met-hemoglobin, glucose oxidase, horseradish peroxidase, BSA, catalase, lysozyme, and cytochrome c indicated improved binding, structure retention, and activities. Nearly 100% of native-like structures of all the seven proteins/enzymes were noted at near monolayer formation of cBSA on GO (400% w/w), and all bound enzymes indicated 100% retention of their activities. A facile, benign, simple, and general method has been developed for the biofunctionalization of GO, and this approach of coating with suitable protein glues expands the utility of GO as an advanced biophilic nanomaterial for applications in catalysis, sensing, and biomedicine.

Serum albumin levels in ischemic stroke and its subtypes: correlation with clinical outcome

OBJECTIVE

Previous studies have associated low serum albumin levels with poor outcome in ischemic stroke. Animal studies also demonstrated neuroprotective effects of serum albumin in focal ischemia. However, there are very limited studies on the association of serum albumin levels with stroke outcome in ischemic stroke divided into subtypes. The present study was carried out to investigate the association of serum albumin levels with outcome in ischemic stroke and its subtypes.

METHODS

The study involved 560 patients. Serum albumin levels were estimated and follow-up interviews were conducted at 3 mo postevent to determine stroke outcome. The association between serum albumin levels and stroke outcome was evaluated by multiple logistic regression analysis after adjustment for potential confounders.

RESULTS

Low levels of albumin associated significantly with poor outcome (score of >3 on the modified Rankin Scale). The adjusted odds ratio was 1.972 (95% confidence interval, 1.103-4.001; P < 0.001). The recurrence of stroke and death rate also was high in patients with low levels of albumin compared with patients with elevated levels of albumin. The reduced level of serum albumin associated significantly with poor outcome in all the stroke subtypes classified according to TOAST (Trial of ORG 10172 in Acute Stroke Treatment).

CONCLUSIONS

Relatively high serum albumin levels in acute stroke decrease poor outcome.

The effect of reactive oxygen species on whole blood aggregation and the endothelial cell-platelet interaction in patients with coronary heart disease

Background

The effect of reactive oxygen species (ROS) on platelet function in coronary heart disease (CHD) is complex and poorly defined. Platelet aggregation studies in healthy volunteers have demonstrated contrasting results when platelets are exposed to ROS. We investigated the effect of ROS on whole blood aggregation (WBA) and the endothelial cell-platelet interaction in patients with CHD.

Methods and Results

ROS generated by xanthine and xanthine oxidase caused a concentration-dependent inhibition of WBA in blood from healthy donors and patients with CHD. In patients with CHD, 100 μM xanthine and 100 mU/ml xanthine oxidase inhibited WBA in response to 3 μg/ml collagen by 28.9% (95% CI 15.9%-41.8%, p < 0.001) and in response to 5 μM ADP by 36.0% (95% CI 9.6%-62.4%, p = 0.005). Using nitrotyrosine expression, platelets isolated from patients with CHD were found to be susceptible to peroxynitrite damage. The addition of 1 × 10⁵ cultured endothelial cells inhibited WBA in response to 3 μg/ml collagen by 31.2% (95% CI 12.2%-50.2%, p < 0.05) and in response to 5 μM ADP by 31.6% (95% CI 2.5-60.7%, p < 0.05). Addition of xanthine and xanthine oxidase did not alter this effect, however pre-treatment of endothelial cells with a nitric oxide synthase inhibitor (L-NAME) partly reversed the inhibition.

Conclusion

ROS inhibit WBA in blood from patients with CHD. Whilst endothelial cells also inhibit WBA, the effect is attenuated by L-NAME, suggesting that nitric oxide is likely to remain an important protective mechanism against thrombosis in CHD.

Investigational therapies for ischemic stroke: neuroprotection and neurorecovery

Stroke is one of the leading causes of death and disability worldwide. Current treatment strategies for ischemic stroke primarily focus on reducing the size of ischemic damage and rescuing dying cells early after occurrence. To date, intravenous recombinant tissue plasminogen activator is the only United States Food and Drug Administration approved therapy for acute ischemic stroke, but its use is limited by a narrow therapeutic window. The pathophysiology of stroke is complex and it involves excitotoxicity mechanisms, inflammatory pathways, oxidative damage, ionic imbalances, apoptosis, angiogenesis, neuroprotection, and neurorestoration. Regeneration of the brain after damage is still active days and even weeks after a stroke occurs, which might provide a second window for treatment. A huge number of neuroprotective agents have been designed to interrupt the ischemic cascade, but therapeutic trials of these agents have yet to show consistent benefit, despite successful preceding animal studies. Several agents of great promise are currently in the middle to late stages of the clinical trial setting and may emerge in routine practice in the near future. In this review, we highlight select pharmacologic and cell-based therapies that are currently in the clinical trial stage for stroke.

Applications of bio-inspired special wettable surfaces

In this review we focus on recent developments in applications of bio-inspired special wettable surfaces. We highlight surface materials that in recent years have shown to be the most promising in their respective fields for use in future applications. The selected topics are divided into three groups, applications of superhydrophobic surfaces, surfaces of patterned wettability and integrated multifunctional surfaces and devices. We will present how the bio-inspired wettability has been integrated into traditional materials or devices to improve their performances and to extend their practical applications by developing new functionalities.

Low serum albumin levels and in-hospital adverse outcomes in acute coronary syndrome

Epidemiological studies have demonstrated an association between low serum albumin levels and coronary heart disease and mortality. Nevertheless, the impact of a low serum albumin level during acute coronary syndrome has not yet been established. The aim of the present study was to investigate whether low serum albumin levels are associated with adverse outcomes in acute coronary syndrome. We enrolled 82 consecutive patients with acute coronary syndrome from whom venous blood for serum albumin measurement was drawn immediately upon hospital admission. Thirty-five patients had a low albumin level (hypoalbuminemia) and 47 had a normal albumin level (normoalbuminemia). In-hospital adverse outcomes (death, acute heart failure, cardiogenic shock, and reinfarction) were recorded during hospitalization in the intensive coronary care unit. The results of our study showed that the incidence of in-hospital adverse outcomes was 43%, with death occurring in 8 patients (10%). In-hospital adverse outcomes occurred more frequently in patients presenting with hypoalbuminemia, whereas mortality did not differ significantly. Univariate analysis showed that hypoalbuminemia was associated with a 2.8-fold greater risk of developing adverse outcomes. This risk was greater in the subgroup of NSTEACS (5.4-fold increased risk), but not in those with STEMI. Adjustment with other covariates revealed that hypoalbuminemia did not predict independently in-hospital adverse outcomes. It interacted with other predictors, especially Killip class II-IV, which was consistently an independent predictor of in-hospital adverse outcomes.

Hyperacute therapies for childhood stroke: a case report and review of the literature

Objective. The optimal management of pediatric patients with arterial ischemic stroke (AIS) is not known. Despite this, goal-oriented, time-sensitive therapies geared to rapid reestablishment of arterial blood flow are occasionally applied with beneficial effects. The inconsistent approach to AIS is in part due to a lack of knowledge and preparedness. Methods. Case report of a 12-year-old male with right middle cerebral artery (MCA) occlusion resulting in dense left hemiplegia and mutism and review of the literature. Intervention(s). Mechanical thrombectomy, intra-arterial administration of rt-PA, vasodilators, and platelet inhibitors, and systemic anticoagulation and subsequent critical care support. Results. Restoration of right MCA blood flow and complete resolution of neurologic deficits. Conclusion. We report the gratifying outcome of treatment of a case of AIS in a pediatric patient treated with hyperacute therapies geared to arterial recanalization and subsequent neurologic critical care and review the pertinent literature. Guidelines for the emergency room management of pediatric AIS from prospective, randomized trials are needed.

When Blood Is Touched

The development of blood-compatible materials is reviewed. It grew from originally simplistic views of physical requirements such as surface charge and wettability, to endothelial cells seeded onto a biodegradable cast, and tissue engineering. In vitro findings grew from the discovery of one specific protein being adsorbed, to that of sequential protein adsorption with complex implications of platelet and white cell adhesion. The main challenge is still the production of small blood vessels (capillaries).

Role of reactive nitrogen species in blood platelet functions

Blood platelets, in analogy to other circulating blood cells, can generate reactive oxygen/nitrogen species (ROS/RNS) that may behave as second messengers and may regulate platelet functions. Accumulating evidence suggest a role of ROS/RNS in platelet activation. On the other hand, an increased production of ROS/RNS causes oxidative stress, and thus, may contribute to the development of different diseases, including vascular complications, inflammatory and psychiatric illnesses. Oxidative stress in platelets leads to chemical changes in a wide range of their components, and platelet proteins may be initial targets of ROS/RNS action. It has been demonstrated that reaction of proteins with ROS/RNS results in the oxidation and nitration of some amino acid residues, formation of aggregates or fragmentation of proteins. In oxidized proteins new carbonyl groups and protein hydroperoxides are also formed. In platelets, low molecular weight thiols such as glutathione (GSH), cysteine and cysteinylglycine and protein thiols may be also target for ROS/RNS action. This review describes the chemical structure and biological activities of reactive nitrogen species, mainly nitric oxide ((*)NO) and peroxynitrite (ONOO(-)) and their effects on blood platelet functions, and the mechanisms involved in their action on platelets.

A lubricious formulation exhibiting reduced thrombogenicity, cell proliferation, and protein adsorption

The adhesion of human platelets, erythrocytes, and leukocytes, the adsorption of protein, and the proliferation of human umbilical vein endothelial cells (HUVEC) on the surface of electropolished stainless steel and the lumen of polyurethane tubing coated with Hydromer's lubricious Duality T8B formulation was evaluated. Following exposure to a platelet-enriched suspension from citrated human whole blood, stainless steel coated with this formulation exhibited significantly reduced adhesion of platelets, erythrocytes, and granulocytes. This reduction in adhesion was confirmed using an immunohistochemical method utilizing antibodies to CD41, CD235, and CD15, respectively. The proliferation of HUVEC cells were significantly reduced when cultured on coated stainless steel. This formulation was also able to significantly reduce the adsorption of plasma proteins and the major protein in tear fluid (lysozyme) to the surface of stainless steel. The nonthrombogenic properties of Duality T8B after application to the lumen of polyurethane tubing were also examined. Following a short-term (3 h) static exposure to citrated human whole blood, microscopic examination revealed that the adhesion of platelets and erythrocytes was reduced significantly, a finding confirmed using anti-CD41 and anti-CD235 antibodies in the immunohistochemical method. A long-term (12 day) study yielded essentially identical results indicating a significant reduction in the adhesion of blood components on the luminal surface of coated polyurethane tubing. In summary, these data indicate that the application of Duality T8B onto surfaces of medical devices, such as catheters, extracorporeal circuitry, and coronary stents, could aid in reducing or preventing not only thrombus formation but also the process of restenosis.

Cell adhesion and proliferation are reduced on stainless steel coated with polysaccharide-based polymeric formulations

Hydromer's polymeric formulations F200 and F202 were evaluated after application to a synthetic substrate for effects on cell adhesion and proliferation. A significant reduction in cell adhesion was observed when cells grown on medical-grade stainless steel coated with these polymers were stained and examined under a fluorescence microscope. This reduction in cell adhesion/proliferation was confirmed when cells were isolated and analyzed by the MTS cell proliferation assay. The rate of growth of cells on F200- and F202-coated stainless steel monitored over a period of 7 days was significantly less than that observed on uncoated stainless steel, suggesting that the rate of growth of cells was reduced. The adhesion/proliferation of human umbilical vein endothelial cells (HUVEC) to coated substrates was also decreased significantly, indicating that the reduction in cell adhesion/proliferation is not restricted to only fibroblasts. Additional studies have indicated that the adhesion/proliferation of murine fibroblasts and human endothelial cells to stainless coated with a modified formulation exhibiting a high degree of lubricity was also significantly reduced. This lubricious formulation was also observed to be effective in reducing platelet adhesion, data supporting the view that lubricity also contributes to a reduction in cell and platelet adhesion. The application of these polymeric coatings on devices designed for medical implantation may not only prevent thrombus formation but may also retard the process of restenosis.

Antithrombogenic polynitrosated polyester/poly(methyl methacrylate) blend for the coating of blood-contacting surfaces

A nitric oxide (NO) donor polyester containing multiple S-nitrosothiol (S-NO) groups covalently attached to the polymer backbone was synthesized through the esterification of poly(ethylene glycol) with mercaptosuccinic acid, followed by the nitrosation of the -SH moieties. The polynitrosated polyester (PNPE) obtained was blended with poly(methyl methacrylate) (PMMA), yielding solid films capable of releasing NO. Scanning electron microscopy analysis showed that acrylic plates and stainless steel intracoronary stents can be coated with continuous and adherent PNPE/PMMA films. After an initial NO burst, these films release NO spontaneously in dry condition or immersed in aqueous solution at constant rates of 1.8 and 180 nmol/g/h, respectively, for more than 24 h at physiological temperature. PNPE/PMMA coated surfaces were shown to inhibit platelet adhesion when in contact with whole blood. These results show that PNPE/PMMA blend can be used for the coating of blood-contacting surfaces, with potential to inhibit thrombosis and restenosis after stenting.

Recent developments in nitric oxide donor drugs

During the 1980s, the free radical, nitric oxide (NO), was discovered to be a crucial signalling molecule, with wide-ranging functions in the cardiovascular, nervous and immune systems. Aside from providing a credible explanation for the actions of organic nitrates and sodium nitroprusside that have long been used in the treatment of angina and hypertensive crises respectively, the discovery generated great hopes for new NO-based treatments for a wide variety of ailments. Decades later, however, we are still awaiting novel licensed agents in this arena, despite an enormous research effort to this end. This review explores some of the most promising recent advances in NO donor drug development and addresses the challenges associated with NO as a therapeutic agent.

Intra-arterial infusion of nitric oxide (NO) - first animal trial

OBJECTIVE

Nitric oxide (NO) is an important signaling molecule that acts in many tissues to regulate a diverse range of physiological processes. NO has been implicated in a number of cardiovascular diseases. Reduced basal NO synthesis or function may lead to: vasoconstriction, elevated blood pressure and thrombus formation. By contrast, overproduction of NO results in vasodilatation, hypotension, vascular leakage, and disruption of cell metabolism. The purpose of this study was to determine the effects of NO gas directly infused into the arteries.

METHODS

The study was performed on 28 rabbits and 10 pigs. We developed a device that enables quantitatively controlled infusion of NO gas, directly into the arteries.

RESULTS

We found that administration of NO gas via arteries caused widening of the blood vessels as well as increasing blood flow in the extremity. It emerges that. These effects persist up to 2-3 h after the NO infusion ceased. Although the NO breaks down when diffused in blood, its influence commences rapidly and continues for a relatively long time.

CONCLUSIONS

Our findings indicate that, administration of NO into blood vessels causes a long lasting vasodilatation and enhanced blood flow. Despite the fact that NO is broken down rapidly.

The ALIAS Pilot Trial

Background and Purpose— High-dose human albumin (ALB) is robustly neuroprotective in rodent stroke models. A phase I dose-escalation study was conducted to assess the safety of ALB therapy in ischemic stroke. We analyzed the data for preliminary evidence of treatment efficacy.

Methods— Eighty-two subjects with acute ischemic stroke (NIH Stroke Scale [NIHSS] of 6 or above) received 25% ALB beginning within 16 hours of stroke onset. Six successive ALB dose tiers were assessed (range, 0.34 to 2.05 g/kg). Forty-two patients also received standard-of-care intravenous tissue plasminogen activator (tPA). Efficacy outcomes were determined at 3 months. We compared the highest three, putatively therapeutic ALB dose tiers (1.37 to 2.05 g/kg) with the lowest three, presumed subtherapeutic doses (0.34 to 1.03 g/kg) and with historical cohort data derived from the NINDS rt-PA Stroke Study.

Results— After adjusting for the tPA effect, the probability of good outcome (defined as modified Rankin Scale 0 to 1 or NIH Stroke Scale 0 to 1 at 3 months) at the highest three ALB doses was 81% greater than in the lower dose-tiers (relative risk [RR], 1.81; 95% confidence interval [CI], 1.11 to 2.94) and was 95% greater than in the comparable NINDS rt-PA Stroke Study cohort (RR, 1.95; 95% CI, 1.47 to 2.57). The tPA-treated subjects who received higher-dose ALB were three times more likely to achieve a good outcome than subjects receiving lower-dose ALB, suggesting a positive synergistic effect between ALB and tPA.

Conclusions— Our data suggest that high-dose ALB therapy may be neuroprotective after ischemic stroke. These results have led to a multicenter, randomized, placebo-controlled efficacy trial of ALB in acute ischemic stroke—the ALIAS Phase III Trial.

Comparison of platelet fibronectin, ADP-induced platelet aggregation and serum total nitric oxide (NOx) levels in angiographically determined coronary artery disease

INTRODUCTION

Coronary thrombosis is an important determinant of prognosis in patients with acute coronary syndromes. Fibronectin is also found in platelets within the alpha secretory granules and secreted following platelet stimulation by a variety of agonist. Available data suggest that expression of platelet fibronectin on the cell surface may indicate a role in platelet aggregation and adhesion to fibrin thrombi and connective tissue. Clear evidence has emerged that a concerted action of nitric oxide (NO) generated by either endothelial or platelet NO synthases regulates platelet activation, causing inhibition of adhesion and aggregation. The aim of the present study was determining and correlating the serum total NO (NOx), platelet fibronectin and ADP-induced platelet aggregation levels in coronary artery disease (CAD) patient subgroups.

MATERIALS AND METHODS

A total of 43 coronary artery disease patients were included in this study. Peripheral blood samples from patients with coronary artery disease were obtained from the Department of Cardiology. Platelet aggregation tests with adenosine diphosphate (ADP) were analyzed by using aggregometer. Platelet fibronectin concentrations were determined by enzyme-linked immunosorbent assay (ELISA). Serum total nitric oxide (NOx) levels were determined by colorimetric method.

RESULTS

In patients with double-vessel disease, platelet fibronectin levels were found to be significantly higher than no-vessel disease (p<0.001), single-vessel disease (p<0.01) and triple-vessel disease (p<0.001). In addition, in patients with single-vessel disease platelet fibronectin levels significantly higher than no-vessel disease (p<0.05). We could not find any significant differences in ADP-induced platelet aggregation and serum NOx values between CAD patient subgroups. There was a positive correlation between platelet fibronectin levels and severity of disease (r=0.315, p<0.05).

Reactive Oxygen Species

Platelets participate not only in thrombus formation but also in the regulation of vessel tone, the development of atherosclerosis, angiogenesis, and in neointima formation after vessel wall injury. It is not surprising, therefore, that the platelet activation cascade (including receptor-mediated tethering to the endothelium, rolling, firm adhesion, aggregation, and thrombus formation) is tightly regulated. In addition to already well-defined platelet regulatory factors, such as nitric oxide (NO), prostacyclin (PGI2), and adenosine, reactive oxygen species (ROS) participate in the regulation of platelet activation. Although exogenously derived ROS are known to affect the regulation of platelet activation, recent data suggest that the platelets themselves generate ROS. Intracellular ROS signaling in activated platelets could be of significant relevance after transient platelet contact with the vessel wall, during the recruitment of additional platelets, and in thrombus formation. This review discusses the potential cellular and enzymatic sources of ROS in platelets, their molecular mechanisms of action in platelet activation, and summarizes in vitro and in vivo evidence for their physiological and potential therapeutic relevance.

Nitric oxide-releasing drugs

Pharmacological compounds that release nitric oxide (NO) have been useful tools for evaluating the broad role of NO in physiology and therapeutics. NO deficiency has been implicated in the genesis and evolution of several disease states. Both medical needs and commercial opportunities have fostered attempts to modulate NO in the human body for therapeutic gain. Strategies for NO modulation encompass antiinflammatory, sexual dysfunction, and cardiovascular indications. Apart from newly developed drugs, several commonly used cardiovascular drugs exert their beneficial action, at least in part, by modulating the NO pathway. This review discusses the fundamental pharmacological properties and mechanisms of action of NO-releasing drugs. Some of these compounds may enter in the clinical arena providing important therapeutic benefits in human diseases.

Nitric oxide donor drugs: current status and future trends

Nitric oxide synthesised in endothelial cells that line blood vessels has a wide range of functions that are vital for maintaining a healthy cardiovascular system. Reduced nitric oxide availability is implicated in the initiation and progression of many cardiovascular diseases and delivery of supplementary nitric oxide to help prevent disease progression is an attractive therapeutic option. Nitric oxide donor drugs represent a useful means of systemic nitric oxide delivery and organic nitrates have been used for many years as effective therapies for symptomatic relief from angina. However, nitrates have limitations and a number of alternative nitric oxide donor classes have emerged since the discovery that nitric oxide is a crucial biological mediator. This review focuses on novel advances and possible future directions in nitric oxide donor drug development.

Vasoactive substances: nitric oxide and endothelial dysfunction in atherosclerosis

The endothelium synthesizes and releases nitric oxide (NO) to maintain homeostatic function. Under basal conditions, endothelium-derived NO maintains a nonthrombogenic surface, prohibits leukocyte attachment, and promotes vascular relaxation. In the setting of clinical syndromes associated with the development of atherothrombosis, there is decreased bioavailable NO owing to diminished synthesis and release in addition to increased generation of reactive oxygen species. These biochemical changes perturb significantly vascular homeostatic mechanisms and promote platelet aggregation, inflammatory cell diapedesis, and vasoconstriction. Endothelial dysfunction may be evaluated using invasive and/or noninvasive techniques, including coronary artery reactivity to acetylcholine and brachial artery ultrasonography, respectively. NO replacement therapies may be initiated to restore deficits associated with dysfunctional endothelium. Strategies to replenish bioavailable NO include the administration of organic nitrosovasodilators or NO donor compounds, therapies to improve NO synthase function, and gene therapy.

Nitric oxide donors and cardiovascular agents modulating the bioactivity of nitric oxide: an overview

Nitric oxide (NO) mediates multiple physiological and pathophysiological processes in the cardiovascular system. Pharmacological compounds that release NO have been useful tools for evaluating the pivotal role of NO in cardiovascular physiology and therapeutics. These agents constitute two broad classes of compounds, those that release NO or one of its redox congeners spontaneously and those that require enzymatic metabolism to generate NO. In addition, several commonly used cardiovascular drugs exert their beneficial action, in part, by modulating the NO pathway. Here, we review these classes of agents, summarizing their fundamental chemistry and pharmacology, and provide an overview of their cardiovascular mechanisms of action.

Nitric oxide: implications for vascular and endovascular surgery

Nitric oxide has a key role in vascular homeostasis. It plays a protective role by suppressing abnormal proliferation of vascular smooth muscle following various pathological situations including atherosclerosis and restenosis after vascular interventions such as balloon angioplasty, stent deployment and bypass grafting. It also has strong antiplatelet and anti-thrombogenic properties. In this review, possible applications to daily vascular and endovascular surgery practice, including systemic use of NO donors, enhancing endogenous production of NO by L-arginine and gene therapy, local delivery strategies and coating stents and grafts with NO-delivering/enhancing chemicals are reviewed.

Nitric oxide insufficiency, platelet activation, and arterial thrombosis

Nitric oxide (NO) was originally discovered as a vasodilator product of the endothelium. Over the last 15 years, this vascular mediator has been shown to have important antiplatelet actions as well. By activating guanylyl cyclase, inhibiting phosphoinositide 3-kinase, impairing capacitative calcium influx, and inhibiting cyclooxygenase-1, endothelial NO limits platelet activation, adhesion, and aggregation. Platelets are also an important source of NO, and this platelet-derived NO pool limits recruitment of platelets to the platelet-rich thrombus. A deficiency of bioactive NO is associated with arterial thrombosis in animal models, individuals with endothelial dysfunction, and patients with a deficiency of the extracellular antioxidant enzyme glutathione peroxidase-3. This enzyme catalyzes the reduction of hydrogen and lipid peroxides, which limits the availability of these reactive oxygen species to react with and inactivate NO. The complex biochemical reactions that underlie the function and inactivation of NO in the vasculature represent an important set of targets for therapeutic intervention for the prevention and treatment of arterial thrombotic disorders.

Attenuation of hypothermia-induced platelet activation and platelet adhesion to artificial surfaces in vitro by modification of hemoglobin to carry S-nitric oxide and polyethylene glycol

Hypothermic cardiopulmonary bypass alters platelet function and hypothermia is associated with postoperative myocardial ischemia. Thrombogenic surfaces such as extracorporeal circuits, vascular graft materials, and components of atherosclerotic plaque induce activation of platelets. The effects of human hemoglobin (Hb) covalently modified to carry S-nitric oxide (NO) functional groups (SNO-Hb), polyethylene glycol (PEG-Hb), and SNO-PEG-Hb on platelet activation were studied. Platelet activation was assessed by cytometric analysis of GPIIb-IIIa activation and P-selectin expression at hypothermic condition (22 degrees C) after stimulation with Hb derivatives. Platelet adhesion and aggregation were measured in a parallel glass plate chamber coated with unmodified Hb, SNO-Hb, PEG-Hb, SNO-PEG-Hb, and collagen. Platelet binding of antibodies to GPIIb-IIIa and P-selectin was significantly enhanced by hypothermic condition and by unmodified Hb. There was significantly less platelet binding of antibodies to GPIIb-IIIa and P-selectin with SNO-Hb, PEG-Hb, and SNO-PEG-Hb compared with unmodified Hb. There was significantly less platelet attachment, adhesion, and aggregation on the SNO-Hb, PEG-Hb and SNO-PEG-Hb coated surfaces compared with unmodified Hb-coated and -uncoated surfaces. SNO-Hb, PEG-Hb, and SNO-PEG-Hb induced less platelet activation at hypothermic temperature, and induced less platelet adhesion and aggregation on thrombogenic surfaces compared with unmodified Hb. The inhibitory effect may be derived from antiadhesive properties of Hb, antiplatelet actions of NO, and molecular barrier action of PEG.

Nitric oxide and postangioplasty restenosis: pathological correlates and therapeutic potential

Balloon angioplasty revolutionized interventional cardiology as a nonsurgical procedure to clear a diseased artery of atherosclerotic blockage. Despite its procedural reliability, angioplasty's long-term outcome can be compromised by restenosis, the recurrence of arterial blockage in response to balloon-induced vascular trauma. Restenosis constitutes an important unmet medical need whose pathogenesis has yet to be understood fully and remains to be solved therapeutically. The radical biomediator, nitric oxide (NO), is a natural modulator of several processes contributing to postangioplasty restenosis. An arterial NO deficiency has been implicated in the establishment and progression of restenosis. Efforts to address the restenosis problem have included trials evaluating a wide range of NO-based interventions for their potential to inhibit balloon-induced arterial occlusion. All types of NO-based interventions yet investigated benefit at least one aspect of balloon injury to a naive vessel in a laboratory animal without inducing significant side effects. The extent to which this positive, albeit largely descriptive, body of experimental data can be translated into the clinic remains to be determined. Further insight into the pathogenesis of restenosis and the molecular mechanisms by which NO regulates vascular homeostasis would help bridge this gap. At present, NO supplementation represents a unique and potentially powerful approach to help control restenosis, either alone or as a pharmaceutical adjunct to a vascular device.

Reduced thrombus formation by hyaluronic acid coating of endovascular devices

Biocompatible stent coatings may alleviate problems of increased (sub)acute thrombosis after stent implantation. Hyaluronic acid (HA), a ubiquitous, nonsulfated glycosaminoglycan, inhibits platelet adhesion and aggregation and prolongs bleeding when administered systemically. However, the effects of immobilized HA for reducing stent platelet deposition in vivo are unknown. We therefore quantified the antithrombotic effects of coating stainless steel stents and tubes with HA using an established baboon thrombosis model under physiologically relevant blood flow conditions. HA-coated and uncoated (control) stents (3.5 mm in diameter, n=32) and stainless steel tubes (4.0 mm in diameter, n=18) were deployed into exteriorized arteriovenous shunts of conscious, nonanticoagulated baboons. Accumulation of (111)In-radiolabeled platelets was quantified by continuous gamma-camera imaging during a 2-hour blood exposure period. HA coating resulted in a significant reduction in platelet deposition in long (4 cm) tubes (0.24+/-0.15 x 10(9) versus 6.12+/-0.49 x 10(9) platelets; P<0.03), short (2 cm) stainless steel tubes (0.18+/-0.06 x 10(9) versus 3.03+/-0.56 x 10(9) platelets; P<0.008), and stents (0.82+/-0.20 x 10(9) versus 1.83+/-0. 23 x 10(9) platelets; P<0.02) compared with uncoated control devices. Thus, HA coating reduces platelet thrombus formation on stainless steel stents and tubes in primate thrombosis models. These results indicate that immobilized HA may represent an attractive strategy for improving the thromboresistance of endovascular devices.