L-arginine improves endothelial vasoreactivity and reduces thrombogenicity after thrombolysis in experimental deep venous thrombosis

Diet and Nutraceuticals for treatment and prevention of primary and secondary stroke: Emphasis on nutritional antiplatelet and antithrombotic agents

Ischemic stroke is a devastating disease that causes morbidity and mortality. Malnutrition following ischemic stroke is common in stroke patients. During the rehabilitation, the death rates of stroke patients are significantly increased due to malnutrition. Nutritional supplements such as protein, vitamins, fish, fish oils, moderate wine or alcohol consumption, nuts, minerals, herbal products, food colorants, marine products, fiber, probiotics and Mediterranean diets have improved neurological functions in stroke patients as well as their quality of life. Platelets and their mediators contribute to the development of clots leading to stroke. Ischemic stroke patients are treated with thrombolytics, antiplatelets, and antithrombotic agents. Several systematic reviews, meta-analyses, and clinical trials recommended that consumption of these nutrients and diets mitigated the vascular, peripheral, and central complications associated with ischemic stroke (Fig. 2). Particularly, these nutraceuticals mitigated the platelet adhesion, activation, and aggregation that intended to reduce the risks of primary and secondary stroke. Although these nutraceuticals mitigate platelet dysfunction, there is a greater risk of bleeding if consumed excessively. Moreover, malnutrition must be evaluated and adequate amounts of nutrients must be provided to stroke patients during intensive care units and rehabilitation periods. In this review, we have summarized the importance of diet and nutraceuticals in ameliorating neurological complications and platelet dysfunction with an emphasis on primary and secondary prevention of ischemic stroke.

Critical Review of Large Animal Models for Central Deep Venous Thrombosis

OBJECTIVE

To review the existing literature on large animal models of central venous thrombosis (CVT) and to evaluate its relevance in regard to the development and testing of dedicated therapeutics applicable to humans.

METHODS

A systematic literature search was conducted in PubMed and Embase. Articles describing an in vivo experimental protocol of CVT in large animals, involving the iliac vein and/or the vena cava and/or the brachiocephalic vein, were included. The primary aim of the study, animal characteristics, experimental protocol, and thrombus evaluation were recorded.

RESULTS

Thirty-eight papers describing more than 30 different protocols were included. Animals used were pigs (53%), dogs (21%), monkeys (24%), and cattle (3%). The median number of animals per study was 12. Animal sex, strain, and weight were missing in 18 studies (47%), seven studies (18%), and eight studies (21%), respectively. CVT was always induced by venous stasis: solely (55%), or in addition to hypercoagulability (37%) or endothelial damage (10%). The size of the vessel used for thrombus creation was measured in four studies (10%). Unexpected animal death occurred in nine studies (24%), ranging from 3% to 37% of the animals. Twenty-two studies (58%) in the acute phase and 31 studies in the chronic phase (82%) evaluated the presence or absence of the thrombus created, and its occlusive characteristic was reported, respectively, in five and 17 studies. Histological examination was performed in 24 studies (63%) with comparison to human thrombus in one study.

CONCLUSION

This review showed advantages and weaknesses of the existing large animal models of CVT. Future models should insist on more rigour and consistency in reporting animal characteristics, as well as evaluating and comparing the thrombus created to human thrombus.

The Midterm Effect of Iliac Vein Stenting following Catheter-directed Thrombolysis for the Treatment of Deep Vein Thrombosis

BACKGROUND

When following catheter-directed thrombolysis (CDT) for deep vein thrombosis (DVT), the stenosed iliac veins is controversy. To evaluate the mid-term outcomes of CDT with or without stent implantation for DVT in the presence of iliac vein compression.

METHODS

Seventy-three patients with iliac vein compression following CDT for acute lower extremity DVT from January 2009 to December 2014 were retrospectively analyzed. There were 32 males and 41 females, with average age of 53.57 ± 15.60 years (median: 45 years, range: 20-79 years). After CDT, patients with iliac vein compression were divided into 2 groups: the stenting group (n = 40) and the nonstenting group (n = 33). Patency rate of the deep vein, chronic change of vessels, clinical, etiological, anatomical, and pathological elements (CEAP) classification, venous clinical severity score, and Villalta scale were chosen to evaluate the midterm and long-term outcomes.

RESULTS

Eighty-eight limbs among the patients (58 unilateral and 15 bilateral) were followed with mean time of 38.38 ± 14.91 months. The difference in vein patency between 2 groups (85.17 ± 25.62 vs. 54.61 ± 40.42) was statistically significant (P < 0.05). According to the C in CEAP classification, the difference in clinical manifestations between the 2 groups was statistically significant (P < 0.05). In addition, the Villalta scale scores were also significantly different between the 2 groups (1.73 ± 2.86 vs. 4.39 ± 5.16, P < 0.05).

CONCLUSIONS

Stent implantation in severely stenosed iliac segments following CDT for lower extremity DVT increased the patency of deep veins and improved midterm quality of life compared with that of nonstenting.

Effects of arginine-based immunonutrition on inpatient total costs and hospitalization outcomes for patients undergoing colorectal surgery

OBJECTIVE

The aim of this study was to assess the effects of an arginine-based immunonutrition intervention for patients undergoing elective colorectal surgery on postsurgical utilization and cost outcomes.

METHODS

This analysis was based on data from two Washington State databases: Surgical Care and Outcomes Assessment Program (SCOAP) linked to the Comprehensive Hospital Abstract Reporting System (CHARS). The sample (N=722) comprises adult patients who underwent elective colorectal surgery with anastomosis in a Washington State hospital that participated in the Strong for Surgery (S4S) initiative between January 1, 2012, and December 31, 2013. A generalized linear model was used to predict the outcomes, adjusting for demographic characteristics and patient health conditions within a multivariate regression framework.

RESULTS

Findings from this study demonstrated significantly fewer readmissions and hospital days for the intervention group during the 180 d after index hospitalization. Clinical benefits included decreased risk for infections and venous thromboembolism. There was a similar pattern toward lower total costs in the immunonutrition patient group; however, these were not statistically different compared with the control group at any time point. Savings in the immunonutrition group were substantial-mean total costs per patient were less by ∼$2500 at index hospitalization, $3500 less through 30 d of follow-up, and $5300 less over 180 d compared with the control group.

CONCLUSION

These findings suggest that arginine-based immunonutrition should be thoroughly evaluated for incorporation into clinical practice for patients undergoing elective surgery. Moreover, there is a need to assess the effects of the intervention in other hospitals both within and outside Washington.

Comparison of Direct Iliofemoral Stenting Following AngioJet Rheolytic Thrombectomy vs Staged Stenting After AngioJet Rheolytic Thrombectomy Plus Catheter-Directed Thrombolysis in Patients With Acute Deep Vein Thrombosis

Purpose: To compare the treatment outcomes in patients with acute proximal deep vein thrombosis (DVT) and iliofemoral stenosis who underwent either direct stenting after AngioJet rheolytic thrombectomy or staged stenting after AngioJet thrombectomy plus catheter-directed thrombolysis with urokinase. Methods: From June 2014 to February 2016, 91 DVT patients underwent 2 treatments for duplex-verified iliofemoral stenosis: direct stenting (n = 46; mean age 54.8 years; 32 men) or staged stenting (n = 45; mean age 56.5 years; 27 men). The degree of patency after thrombectomy or thrombolysis was evaluated using the Venous Registry Index (VRI), while the risk of postthrombotic syndrome (PTS) was evaluated according to the Villalta scale. Patients were followed with periodic duplex ultrasound scans up to 1 year. Results: The technical success rates were 100% in both groups; there was no 30-day mortality. Immediate (24-hour) clinical improvement was achieved in 42 (91%) of 46 direct group patients vs 33 (73%) of 45 staged group patients (p<0.001). A significant reduction (p<0.001) in the length of hospital stay was noted in the direct group (4.59±0.91) compared with that in the staged group (5.8±1.6). The stents used in the direct group were longer but with similar diameter compared with the staged group. The thrombolysis rates were 81.50%±5.76% in the direct group and 85.67%±3.84% in the staged group (p<0.001). The VRIs declined (improved) significantly in both groups (11.68±1.92 to 3.21±1.44 in the direct group and 12.17±2.29 to 2.36±1.19 in the staged group, both p<0.001). The Villalta scores were significantly better in the staged group (p<0.001). Recurrent DVT occurred in 2 patients in the direct group. The primary patency rates at 1 year were 93.5% in the direct group and 97.8% in the staged group (p=0.323). Conclusion: Both direct and staged stenting are effective treatment modalities for patients with acute proximal DVT. Compared with staged stenting, direct stenting provides similar treatment success and a significant reduction in the length of hospital stay; however, it has lower thrombolysis efficacy, and the risk of PTS at 1 year is greater with direct stenting.

Enhancement of endothelial function inhibits left atrial thrombi development in an animal model of spontaneous left atrial thrombosis

BACKGROUND

Left atrial (LA) thrombosis is an important cause of systemic embolization. The SPORTS rat model of LA thrombi (Spontaneously-Running Tokushima-Shikoku), which have a unique characteristic of high voluntary wheel running, was previously established. The aim of the present study was to investigate how SPORTS rats develop LA thrombi.

METHODS AND RESULTS

Nitric oxide (NO) produced from cardiovascular endothelial cells plays an important protective role in the local regulation of blood flow, vascular tone, and platelet aggregation. No evidence of atrial fibrillation or hypercoagulability in SPORTS rats regardless of age was found; however, SPORTS rats demonstrated endothelial dysfunction and a decrease of NO production from a young age. In addition, endothelial NO synthase activity was significantly decreased in the LA and thoracic aorta endothelia of SPORTS rats. While voluntary wheel running was able to intermittently increase NO levels, running did not statistically decrease the incidence of LA thrombi at autopsy. However, L-arginine treatment significantly increased NO production and provided protection from the development of LA thrombi in SPORTS rats.

CONCLUSIONS

They present study results indicate that NO has an important role in the development of LA thrombus, and endothelia pathways could provide new targets of therapy to prevent LA thrombosis.

Arginase blockade lessens endothelial dysfunction after thrombosis

INTRODUCTION

Acute arterial thrombosis causes endothelial dysfunction due to decreased nitric oxide bioactivity. Increased arginase activity may modulate intracellular L-arginine levels, the substrate for nitric oxide. The purpose of this study was to identify the role of arginase in endothelial dysfunction in cell culture and in the vasomotor response of arteries exposed to thrombus.

METHODS

Rat aortic endothelial cells were exposed to thrombin at different time points. The cell extract was analyzed by immunoblotting and real-time polymerase chain reaction. Adult male rats underwent infrarenal aortic thrombosis by clip ligature for 1 hour. Infrarenal aortic ring segments were harvested and placed in physiologic buffer baths, and a force transducer was used to measure endothelial-dependent relaxation (EDR) and endothelial-independent relaxation (EIR). Arginase blockade was performed by incubating infrarenal aortic ring segments with arginase inhibitors for 1 hour before measuring EDR. Whole tissue extracts also underwent immunoblot analysis. The EDR and EIR curves were compared with analyses of variance.

RESULTS

A 6.76 +/- 1.4-fold induction in arginase I message levels (P = .001) was found in rat aortic endothelial cells exposed to thrombin (30 U/mL), and arginase I protein levels increased 2.1 times. The eight infrarenal aortic ring segments exposed to thrombosis for 1 hour had diminished EDR curves compared with 14 nonthrombosed normal segments (controls). The maximum (+/- SEM) EDR (acetylcholine 10(-5)M dose) in control infrarenal aortic ring segments was 108% +/- 4.3% compared with 63% +/- 6.2% for thrombosed infrarenal aortic ring segments (P < .001). Exposure to arterial thrombosis resulted in a 3.8-times increase in arginase I protein levels in infrarenal aortic ring segments. Preincubation of nine infrarenal aortic ring segments with the nonspecific (difluoromethylornithine) and six with specific ([S]-[2-boronoethyl]-L-Cysteine-HCl [BEC]) arginase inhibitor for 1 hour significantly increased the maximum EDR compared with untreated thrombosed segments (104 +/- 5.2, 108 +/- 7.6 vs 63% +/- 6.2, P < .001). EDR curves for difluoromethylornithine- and BEC-treated infrarenal aortic ring segments were superimposed on control EDR curves. The EIR and the vasoconstriction with norepinephrine for all groups were similar.

CONCLUSION

Endothelial cells exposed to thrombin have increased arginase I messenger RNA and protein levels. Arterial thrombosis causes endothelial dysfunction without affecting smooth muscle responsiveness. Arginase blockade can lead to normalization of arterial vasomotor function.

Chronically impaired endothelial vasoreactivity following oversized endovascular introducer sheath placement in porcine iliac arteries: implications for endovascular therapy

The conventional endovascular aortic aneurysm procedure entails the placement of oversized introducer sheaths in relatively normal ileofemoral arteries to allow the delivery and deployment of endovascular prosthesis. Endoluminal manipulation with passage of oversized endoluminal devices can lead to endothelial denudation, resulting in impaired cellular function. The purpose of this study was to assess the time course of endothelial function with vasoreactivity following oversized endovascular sheath insertion ranging from 1 day to 16 weeks in normal porcine iliac arteries. Following oversized introducer sheath placement in bilateral iliac arteries, vasoreactivity was tested using both endothelium-dependent and -independent vasodilators. Intravascular ultrasonography showed a significant reduction in the luminal area at 12 and 16 weeks. This was similarly supported by morphometric analysis, which showed increased medial thickness with an elevated intima to media ratio at the same time course. Endothelium-dependent relaxation to bradykinin, calcium ionophore A23187, serotonin, and adenosine diphosphate all uniformly displayed attenuated endothelial dysfunction at all time points when compared with the control group. In contrast, endothelium-independent relaxation showed a decreased vasoresponsiveness at 4 weeks. In conclusion, this study underscored the detrimental and chronic endothelial dysfunction in a normal artery caused by oversized introducer sheath placement. Chronically impaired endothelial function may play a role leading to iliofemoral artery thrombosis or late occlusion, which were well-recognized adverse events following endovascular aneurysm procedures. Our study underscores the importance of appropriate patient selection to minimize potential sheath oversize and endograft device miniaturization to avoid vessel wall injury and maintain vasoreactivity.

Rheolytic pharmacomechanical thrombectomy in experimental chronic deep vein thrombosis: effect of L-arginine on thrombogenicity and endothelial vasomotor function

PURPOSE

Endovascular removal of intravascular thrombus using the AngioJet rheolytic thrombectomy (RT) system has been shown to be clinically effective. This system also permits the concomitant infusion of thrombolytic agent followed by thrombectomy, thus creating a novel strategy known as pharmacomechanical thrombectomy (PMT). Although these interventions have gained wide clinical application, little is known regarding the vessel wall response following thrombectomy therapy. The aims of this study were to assess the effect of thrombectomy interventions on endothelial function in a porcine model of deep venous thrombosis (DVT) and to evaluate the effect of nitric oxide (NO) precursor L-arginine on endothelial function following thrombectomy therapy.

METHODS

Deep vein thrombosis was created in bilateral iliac veins by deploying a self-expanding stent-graft incorporating an intraluminal stenosis from a groin approach. Five pigs underwent sham operation. Following 14 days of DVT, animals were randomized to three groups: the first group received RT treatment (RT group, n = 5); the second group received pharmacomechanical thrombectomy (PMT) with tissue plasminogen activator (alteplase 10 mg; PMT group, n = 5); and the third group received PMT with tPA plus intravenous L-arginine (20 mmol/l) (arginine group, n = 5). Iliac vein patency was evaluated by venography and intravascular ultrasound at 1 week. Nitric oxide level was determined by a chemiluminescent assay of the nitrite/nitrate metabolites (NO(x)). Thrombogenicity was evaluated by radiolabeled platelet and fibrin deposition. Veins were harvested and evaluated with light microscopy and scanning electron microscopy (SEM). Endothelial function was evaluated using organ chamber analysis.

RESULTS

The luminal areas in the sham, RT, PMT, and arginine groups were 34 +/- 10 mm(2), 21 +/- 13 mm(2), 35 +/- 18 mm(2), and 37 +/- 16 mm(2), respectively. All iliac veins remained patent at 2 weeks. No difference in endothelial cell structure was observed between the three treatment groups by means of light microscopic or SEM examination. A decrease in platelet deposition occurred in the arginine group compared to the RT and PMT groups (P < 0.05). The arginine group also showed a greater endothelium-dependent relaxation compared to the RT or PMT groups in response to A23187, bradykinin, and ADP (P < 0.05). Local NO(x) level was higher in the arginine group than in the RT or PMT group (2.6 +/- 0.6 micromol/l versus 0.3 +/- 0.1 micromol/l and 0.3 +/- 0.2 micromol/l; P < 0.01).

CONCLUSIONS

AngioJet RT and PMT interventions resulted in similar attenuated endothelium-dependent vasoreactivity and morphologic effect. L-Arginine supplementation preserves endothelial vasoreactivity and reduces platelet deposition following PMT in iliac DVT. Additionally, L-arginine enhances NO production at sites of venous thrombosis. The NO precursor L-arginine may have a therapeutic potential in preserving endothelial function following mechanical thrombectomy.

Effect of a low-dose oral contraceptive on venous endothelial function in healthy young women: preliminary results

BACKGROUND

A possible increase in the incidence of venous thromboembolic events has been reported among users of third generation oral contraceptives. The objective of this study was to evaluate the effect of a low dose oral contraceptive (15 microg ethinyl estradiol/60 microg gestodene) on the venous endothelial function of healthy young women.

METHODS

Prospective case control study using the dorsal hand vein technique. Venous endothelial function was evaluated at baseline and after 4 months in the oral contraceptive users group (11 women) and in a control group (9 women). After preconstriction of the vein with phenylephrine, dose-response curves for acetylcholine and sodium nitroprusside were constructed.

RESULTS

In the contraceptive users group, a reduction occurred in the maximum venodilation response to acetylcholine and sodium nitroprusside after 4 months of oral contraceptive use, but this difference was not statistically significant (P > 0.05). No significant changes were detected in maximum venodilation responses to acetylcholine and sodium nitroprusside at the 4-month time point in the control group.

CONCLUSION

This study found no significant impairment of endothelium-dependent or independent venodilation in healthy young women following oral contraceptive use. Further studies are necessary using the same methodology in a larger sample over a longer follow-up period.

Arginase activity is increased by thrombin: a mechanism for endothelial dysfunction in arterial thrombosis

BACKGROUND

Earlier observations implicate arterial thrombosis causing endothelial dysfunction by decreasing nitric oxide (NO) levels. NO levels are restored by regional L-arginine supplementation in animal models. The purpose of this study was to investigate the roles of thrombus components in NO generation.

STUDY DESIGN

Human umbilical vein endothelial cells were harvested and cultured. The thrombus components thrombin, thrombin receptor agonist peptide (TRAP), and fibrin were added to a media of confluent human umbilical vein endothelial cells. Endothelial nitric oxide synthase (eNOS) activity was assayed by measuring conversion of L-arginine to L-citrulline. Endothelial NOS mRNA levels were quantitated using real-time polymerase chain reaction. Cellular membrane transport of L-arginine through the y+ channel was assayed with (14)C-labeled L-arginine. Arginase activity was determined as the conversion of (14)C L-arginine to (14)C urea and trapped as Na(2)(14)CO(3) for scintillation counting. Arginase protein amounts were assessed using Western blotting.

RESULTS

Endothelial cells exposed to thrombin for 4 hours led to increased arginase activity. Thrombin (10 U/mL) caused a 1.6-fold increase compared with that in controls (320+/-29 microM urea/min versus 194+/-10 microM urea/min, p=0.03), and thrombin (30 U/mL) increased arginase activity 2.1-fold (398+/-27 microM urea/min, p < 0.001, versus controls); thrombin at 1 U/mL and fibrin had no effect. TRAP (50 microM) had an effect similar to that of thrombin 10 U/mL (316+/-21 microM urea/min, p < 0.01, versus controls). Protein amounts of arginase corresponded with activity levels. Neither eNOS nor inducible nitric oxide synthase (iNOS) activities were affected by exposure to thrombin and TRAP for 4 hours. Similarly, quantification of eNOS, iNOS, and endothelin-1 mRNA did not change, although CL-100, a known thrombin-inducible gene, was upregulated. Finally, transport of L-arginine into endothelial cells was unaffected by thrombin, TRAP, and fibrin exposure.

CONCLUSIONS

Endothelial cells exposed to thrombin have increased arginase enzymatic activity, and the remainder of NO generation capability is unaffected. L-arginine supplementation or arginase blockade may counteract endothelial dysfunction in the setting of acute arterial thrombosis.

The cardiovascular risk marker asymmetrical dimethylarginine is not affected by venous thromboembolism

Asymmetrical dimethylarginine (ADMA) is an endogenous inhibitor of endothelial nitric oxide synthase, causes vasoconstriction, impairs cardiac function, and may predict cardiovascular risk. The prognostic value of plasma ADMA concentrations in acute vascular situations may be confounded by concomitant factors such as clot formation. In an effort to address the effect of hemostatic system activation, the authors have measured plasma concentrations of ADMA, its stereoisomer symmetrical dimethylarginine (SDMA), and L-arginine in 74 patients with suspected deep vein thrombosis (DVT). DVT was confirmed by sonography or venography in 39 subjects. There was no difference of L-arginine, ADMA, or SDMA (all P > 0.05) between subjects with or without DVT. ADMA correlated with SDMA, L-arginine, and plasma creatinine (all P < 0.05) but not with age, body mass index, D-dimer, thrombus extension, or history of symptoms. Venous thrombembolism does not influence circulating ADMA concentrations. The lack of association between ADMA and DVT argues against a contribution of endogenous NO synthase inhibition in hemostatic systemic activation.