Loss of high-affinity prostacyclin receptors in platelets and the lack of prostaglandin-induced inhibition of platelet-stimulated thrombin generation in subjects with spinal cord injury

Application of Nanoliposome Alprostadil in the Perioperative Period of Percutaneous Coronary Intervention to Reduce In-Stent Restenosis: A Systematic Review and Meta-Analysis

Background

In-stent restenosis (ISR) is a common complication after percutaneous coronary intervention (PCI) surgery for patients with coronary atherosclerotic heart disease (CHD). Reports indicate alprostadil may reduce ISR, and this study aimed at reviewing and summarizing the effect of nanoliposome alprostadil on ISR by meta-analysis.

Methods

Articles were searched from databases, and meta-analysis was performed in Review Manager software. Funnel plots were performed to evaluate the publication bias, and sensitivity analysis was performed to determine the robustness of the overall treatment effects.

Results

Initially, 113 articles were identified, and 5 studies of 463 subjects were included for analysis eventually. The primary endpoint, i.e., the occurrence of ISR after PCI, occurred in 11.91% of the alprostadil treatment group (28 from 235 patients) vs. 21.49% of the conventional treatment group (49 from 228 patients) and showed a statistical significance in our pooled data (χ² = 7.654, P=0.006), while there was no statistically significant difference in all of the separate studies. We observed no statistical methodological heterogeneity among the studies (P=0.64, I² ≈ 0%). The pooled odds ratio (OR) of the occurrence of ISR was 49% in a fixed-effect model, and the 95% confidence boundary (95% CI) was 29% to 81%. The funnel plot did not show serious publication bias, and sensitivity analysis showed well robustness of the overall treatment effect. Discussion. In conclusion, the early application of nanoliposome alprostadil after PCI could effectively reduce the occurrence of ISR, and the overall effect of alprostadil treatment in reducing ISR after PCI was relatively stable.

Incidence and risk factors of deep vein thrombosis in patients with spinal cord injury: a systematic review with meta-analysis

Background

Spinal cord injury (SCI) is a highly disabling disease with huge public health burden. The complications associated with it, especially deep vein thrombosis (DVT), further aggravate the disability.

Objective

To explore the incidence and risk factors of DVT after SCI, in order to provide guidance for disease prevention in the future.

Methods

A search was performed on PubMed, Web of Science, Embase, and Cochrane database up to November 9, 2022. Literature screening, information extraction and quality evaluation were performed by two researchers. The data was later combined by metaprop and metan commands in STATA 16.0.

Results

A total of 101 articles were included, including 223,221 patients. Meta-analysis showed that the overall incidence of DVT was 9.3% (95% CI: 8.2%-10.6%), and the incidence of DVT in patients with acute and chronic SCI was 10.9% (95% CI: 8.7%-13.2%) and 5.3% (95% CI: 2.2%-9.7%), respectively. The incidence of DVT decreased gradually with the accumulation of publication years and sample size. However, the annual incidence of DVT has increased since 2017. There are 24 kinds of risk factors that may contribute to the formation of DVT, involving multiple aspects of the baseline characteristics of the patient, biochemical indicators, severity of SCI, and comorbidities.

Conclusions

The incidence of DVT after SCI is high and has been gradually increasing in recent years. Moreover, there are numerous risk factors associated with DVT. Comprehensive preventive measures need to be taken as early as possible in the future.

Systematic Review Registration

www.crd.york.ac.uk/prospero, identifier CRD42022377466.

Isolation and study of insulin activated nitric oxide synthase inhibitory protein in acute myocardial infarction subjects

Insulin inhibits platelet aggregation through nitric oxide synthesis by stimulating platelet insulin activated nitric oxide synthase. Impaired platelet insulin activated nitric oxide synthase in acute myocardial infarction (AMI) patients had been reported and thus our aim was to identify and isolate the factors impairing insulin activated nitric oxide in acute myocardial infarction patients' plasma and study its effect on platelets aggregation in vitro. The insulin activated nitric oxide synthase inhibitor was identified as a protein and was purified from the plasma of AMI subjects using DEAE cellulose and Sephadex G-50 column, molecular weight determined by SDS-PAGE, nitric oxide quantified by methaemoglobin method, inhibitor protein quantified in plasma by immunoblot and ELISA, platelet aggregation studies done using an aggregometer, thromboxane-A2 in the platelets determined by radioimmunoassay, (125)I-insulin radioligand binding studies done using normal subject platelets. The purified nitric oxide synthase inhibitor protein was ~66 kDa, concentration in AMI subjects' plasma varied from 114 to 9,090 μM and was undetected in normal subjects' plasma. The inhibitor protein competes with insulin for insulin receptor binding sites. The Incubation of the normal subject PRP with 5.0 μM inhibitor for 30 min followed by 0.4 μM ADP addition caused platelet aggregation in vitro, 130 μM aspirin or 400 μU insulin/ml addition was able to abrogate 0.4 μM ADP induced platelet aggregation even in the presence of 5.0 μM inhibitor. A potent inhibitory protein against insulin activated nitric oxide synthase in platelets appears in circulation of AMI subjects impairing nitric oxide production, potentiating ADP induced platelet aggregation and increasing the thromboxane-A2 level in platelets.

Non-conventional hemostatic risk factors for coronary heart disease in individuals with spinal cord injury

STUDY DESIGN

Review.

OBJECTIVES

In subjects with spinal cord injury (SCI), there is strong evidence for platelet hyperactivity, which may stimulate atherosclerosis and coronary heart disease (CHD). The literature was reviewed.

BACKGROUND

Individuals with SCI develop premature CHD. In addition to the conventional risk factors associated with CHD, there are pathologic hematological factors involved in atherogenesis that are similar to those that have been demonstrated in individuals with diabetes, and these hematological factors might affect individuals with SCI. One such hematological factor, platelet aggregation, is essential for the development of CHD, which results from thrombus formation in the coronary vasculature. Prostacyclin (PGI(2)) is a potent inhibitor of platelet aggregation and is thought to have a beneficial role in inhibiting atherogenesis; therefore, it is possible that individuals with SCI have impaired PGI(2) receptor function.

METHODS

We reviewed the literature by conducting a search using PubMed (1970-2007).

RESULTS

Acute thrombosis is emerging as an important factor in the etiology of CHD and therefore could mediate the risk of CHD in persons with SCI, in addition to previously known risk factors such as hyperlipidemia, hypertension, hyperlipidemia, diabetes mellitus and hyperinsulinemia. Because PGI(2) may retard atherogenesis through its inhibitory effects on platelet function, we discuss the effects of PGI(2) on platelets in persons with SCI in this review.

CONCLUSIONS

Subjects with chronic SCI develop abnormal platelet function, resulting in the production of atherogenic and thrombogenic factors for the following reasons: (1) the PGI(2) and insulin receptors on their platelets are impaired; (2) thrombin generation and platelet-derived growth factor release are elevated; (3) insulin-induced nitric oxide production by platelets is markedly impaired; and (4) a circulating antibody (immunoglobulin G (IgG)) blocks the antithrombotic effect of both insulin and PGI(2) receptors. Thus, this IgG molecule is thought to be one of the pathological mediators of the increased incidence of CHD in individuals with SCI.

Lower-extremity functional electrical stimulation decreases platelet aggregation and blood coagulation in persons with chronic spinal cord injury: a pilot study

BACKGROUND

Individuals with spinal cord injury (SCI) develop premature cardiovascular disease. Regular exercise reduces the incidence and symptoms of cardiovascular disease in able-bodied individuals; these salutary effects of exercise have not been documented in persons with SCI.

OBJECTIVE

To evaluate the effects of functional electrical stimulation leg cycle ergometry (FES-LCE) exercise training on platelet aggregation and blood coagulation in persons with SCI.

PARTICIPANTS

Subjects (n=14) with stable chronic (>1 year) paraplegia (T1-T10) or tetraplegia (C4-C8).

METHODS

Blood samples were collected before and after the first and eighth sessions (2 sessions per week for 4 weeks) of FES exercise.

RESULTS

Platelet aggregation was inhibited by 20% after the first session and by 40% (P < 0.001) after the eighth session. Thrombin activity was unchanged after the first session (10.7 +/- 0.85 s to 10.43 +/- 0.56 s) and decreased after the eighth session (12.5 +/- 1.98 s to 11.1 +/- 1.7 s; P < 0.0003). Antithrombin III activity increased after the first (103.8% +/- 8.9% to 110% +/- 6.9%; P < 0.0008) and eighth sessions (107.8% +/- 12.1% to 120.4% +/- 13.1%; P < 0.0001). Cyclic adenosine monophosphate increased after the first (9.9% + 2.5% to 15.8% +/- 3%; P < 0.001) and eighth sessions (17.8% +/- 4.2% to 36.5% +/- 7.6%; P < 0.0001). After the eighth session, factors V and X increased significantly (88% +/- 27% to 103% +/- 23%, P < 0.0001; 100% +/- 40% to 105% +/- 7%, P < 0.01, respectively); factors VII and VIII and fibrinogen did not change significantly. A significant reduction in platelet activation/aggregation was demonstrated in response to FES-LCE. The decrease in thrombin level was caused by the simultaneous increase in antithrombin activity.

CONCLUSION

These findings provide new insight into the potential protective effects of FES-LCE against the risk of cardiovascular disease.

Measurement of coronary artery calcification by electron beam computerized tomography in persons with chronic spinal cord injury: evidence for increased atherosclerotic burden

BACKGROUND/OBJECTIVE

Individuals with spinal cord injury (SCI) have been reported to have an increased prevalence of premature cardiovascular disease. Whether the increased risk of disease is owing to clustering of traditional cardiac risk factor or is over and above that predicted by risk factors was addressed.

METHODS

Ninety-one persons with chronic SCI were studied for subclinical atherosclerosis. Cardiac risk factors and coronary artery calcium (CAC) was compared to matched non-SCI controls. The 273 controls were 3:1 matched for age, gender, ethnicity and risk factors and were drawn from a national database of over 30,000 asymptomatic persons undergoing coronary scanning.

RESULTS

Seventy-six men and 15 women were studied. Average age was 49.7+/-12 years. Duration of injury was 19.7+/-10 years. The ethnicity of the study cohort included 36% Caucasian, 49% Latino, 10% African American, and 5% other. The mean calcium score of the SCI group was significantly greater than the control group (75+/-218 versus 28+/-104, P<0.001). The prevalence of any CAC score was greater in the SCI population than the control population (51 versus 39%, P<0.05), as was CAC score >100 (16 versus 7%, P<0.01). Women with SCI had a significantly lower CAC score than men (mean score: 12 versus 86, P<0.01).

CONCLUSION

Patients with SCI were shown to have greater atherosclerotic burden than able-bodied controls. Of note, and unexplained, this finding is beyond that explained by the clustering of traditional risk factors. On the basis of these findings, increased attention should be directed toward the prevention of coronary heart disease in those with SCI.

Molecular regulation of platelet-dependent thrombosis

Hemostasis is a normal process preventing the sequelae of uncontrolled hemorrhage. In certain settings, these same processes cause adverse clinical events due to thrombotic occlusion of a vessel. The majority of unstable coronary syndromes result from disruption of an atherosclerotic plaque, leading to the exposure of subintimal contents, which triggers coagulation and the formation of a platelet-rich thrombus. The central role of platelet activation in the events that lead to vessel occlusion is well known. However, this process is complex and influenced by a myriad of cellular and plasma-derived mediators that regulate the balance between occlusive and nonocclusive thrombosis.

Effects of oxandrolone, an anabolic steroid, on hemostasis

This study evaluated the short-term effects of oxandrolone, an anabolic androgenic synthetic steroid, on blood coagulation and the hemostatic/fibrinolytic system in healthy individuals. Subjects (n = 14) were administered oxandrolone (10 mg twice daily) for 14 days. Blood was obtained on days 0, 1, 3, 7, 9, 14, and then at day 42 (28 days after discontinuation of the drug). Samples were analyzed for the plasma plasminogen, plasminogen activator inhibitor (PAI-1), fibrinogen, and coagulation factors (II, V, VII, VIII, and X). After 7 days of administration of oxandrolone, the plasma plasminogen level significantly increased [100% +/- 21% to 174% +/- 21% (P < 0.0001)]. PAI-1 was significantly decreased at day 3 [16 +/- 9 to 7 +/- 4 mg/dL (P < 0.01)]. Coagulation factors II and V significantly increased at day 14 [88 +/- 15 to 122 +/- 11 (P < 0.005) and 105 +/- 21 to 179 +/- 36% (P < 0.0001)], respectively. Factor VII level decreased by day 3 [91% +/- 26% to 83% +/- 18%, NS], but after 14 days factor VII level returned to baseline (91% +/- 26% to 93% +/- 19%, NS). The increase of factor VIII level was not significant (111% +/- 64% to 125% +/- 55%, NS). Factor X increased steadily over 14 days of drug treatment [96% +/- 11% to 107% +/- 25%, NS] and after discontinuation, decreased and returned to baseline by day 42 [107% +/- 25% to 89% +/- 25%, NS]. Fibrinogen decreased by 22% +/- 12%, (NS). Administration of oxandrolone, to healthy young men was associated with a significant increase in select blood coagulation factors and plasminogen. These changes create a state of potential hypercoagulability that appears to be counterbalanced by increased fibrinolytic activity to maintain homeostasis.

Effects of prostaglandin E1, melatonin, and oxytetracycline on lipid peroxidation, antioxidant defense system, paraoxonase (PON1) activities, and homocysteine levels in an animal model of spinal cord injury

STUDY DESIGN

Investigation of the effects of prostaglandin E1, melatonin, and oxytetracycline on lipid peroxidation, antioxidant and paraoxonase activities, and homocysteine levels in an experimental model of spinal cord injury.

OBJECTIVES

To determine the antioxidant efficacy of prostaglandin E1, melatonin, and oxytetracycline and whether paraoxonase and homocysteine can be used as monitoring parameters in the acute oxidative stress of spinal cord injury.

SUMMARY OF BACKGROUND DATA

Melatonin has been found useful in spinal cord injury in previous studies. No study exists investigating the effects of melatonin, prostaglandin E1, and oxytetracycline as well as the response type of paraoxonase enzyme and homocysteine levels in the acute oxidative stress of spinal cord injury.

METHODS

Sixty-three male albino Wistar rats were anesthetized with 400 mg/kg chloral hydrate and divided into 5 groups. The G1 (n = 7) control group provided the baseline levels. G2-G5 underwent T3-T6 total laminectomies and spinal cord injuries by clip compression at the T4-T5 levels. Medications were applied to G3-G5 right after clip compression. Hence, G2 constituted laminectomy + injury, G3 laminectomy + injury + prostaglandin E1; G4 laminectomy + injury + melatonin, and G5 laminectomy + injury + oxytetracycline groups. Animals were decapitated either the first or fourth hour after injury. Spinal cord tissue and blood malonyldialdehyde and plasma homocysteine levels, plasma glutathione peroxidase, superoxide dismutase, paraoxonase activities were assayed. The SPSS 9.0 program was used for statistical analysis and graphics. Intergroup comparisons were made by Bonferroni corrected Mann Whitney U test (P < 0.025) and intragroups comparisons by Wilcoxon Rank test (P < 0.03).

RESULTS

In injury groups, plasma homocysteine levels decreased and paraoxonase activities increased as erythrocyte superoxide dismutase levels and plasma glutathione peroxidase activities decreased in parallel to increases of tissue and blood malonyldialdehyde levels. These alterations were relatively suppressed by prostaglandin E1, melatonin, and oxytetracycline administrations in varying degrees. Melatonin was the most powerful agent, particularly at the fourth hour. Oxytetracycline was also effective, both at the first and fourth hour. Prostaglandin E1 was effective in comparison to injury group, but not as much as melatonin and oxytetracycline.

CONCLUSIONS

Melatonin and oxytetracycline are effective in preventing lipid peroxidation in spinal cord injury. Paraoxonase and homocysteine can be used in monitoring the antioxidant defense system as well as superoxide dismutase and plasma glutathione peroxidase, both in injury and medicated groups.

Circulating heavy chain IgG, a pathological mediator for coronary artery disease, recognizes platelet surface receptors of both prostacyclin and insulin

Although an increased incidence of premature cardiovascular disease has been determined to be the major cause of mortality in subjects with chronic spinal cord injury the identity of the pathophysiological mediators of cardiovascular disease in spinal cord injury remains obscure. Because both insulin and prostacyclin could be important in the prevention of thrombosis, the status of insulin-induced nitric oxide production and the prostacyclin high-affinity receptor interaction in platelets in subjects with spinal cord injury was studied. It was established that the insulin-induced nitric oxide synthesis in platelets from spinal cord-injured subjects was markedly impaired (0.053-0.058, P = 0.37-0.44) compared to (0.062-0.53 microM/10(8) platelets, P < 0.001) due to the presence of a free heavy chain IgG (Mr 47 kDa) in the circulation of subjects with spinal cord injury. This IgG not only blocked insulin receptor binding sites (without affecting dissociation constant of the hormone binding, Kd1 = 2 x 10(-9) M) for the synthesis of nitric oxide but also blocked the prostacyclin receptor interaction in normal platelets. Since the presence of circulating heavy chain of IgG could block the antithrombotic effect of both insulin and prostacyclin, the free heavy chain of the IgG molecule was thought to be one of the pathological mediators for the increased incidence of cardiovascular disease in individual with spinal cord injury. The cross-reactivity of the free heavy chain with two different receptors antigens was thought to be related to the presence of several regions of homology in the amino acid sequence in the insulin and prostacyclin receptor molecules.

Impaired circadian variations of haemostatic and fibrinolytic parameters in tetraplegia

Spinal cord injured patients are at increased risk of developing deep vein thrombosis (DVT). Whether these patients have increased blood levels of prothrombotic markers remains to be clarified. In general, the risk of developing DVT is highest in the morning hours. In healthy humans, several haemostatic and fibrinolytic parameters exhibit circadian variations, but it is not known whether this also applies to those with spinal cord injury. The aim of the present study was to examine possible circadian variations in prothrombotic markers in tetraplegic patients. We studied six patients with complete tetraplegia and eight control subjects with repetitive blood sampling over a 24 h period. While the control subjects showed marked circadian variations in factor VIII activity, prothrombin fragments 1+2 and D-dimer levels, the tetraplegic patients did not (P < 0.05). Circadian variation in plasminogen activator inhibitor type-1 was present in both groups, being most marked (P < 0.05) in tetraplegia. We conclude that the circadian variations of several factors of the haemostatic and fibrinolytic systems are impaired in spinal cord injury. This could possibly reflect a deregulated autonomic nervous system, leading to a dysfunctional link between central and peripheral circadian oscillators.

Platelet-stimulated thrombin and PDGF are normalized by insulin and Ca2+ channel blockers

Coronary artery disease is accelerated in chronic spinal cord injury (SCI). Because prostacyclin (PGI2) may retard atherogenesis through its inhibitory effects on platelet function, the role of PGI2 on SCI platelets was determined. The SCI platelets were neither hypersensitive to aggregating agonists nor resistant to the inhibitory effect of PGI2, but PGI2 failed to inhibit platelet-stimulated thrombin generation and the release of platelet-derived growth factor (PDGF) in SCI. Because thrombin and PDGF are atherogenic mitogens, the generation of these mitogens was investigated. Both the release of PDGF and thrombin generation in SCI platelets were higher when compared with control (n = 12). Treatment of non-SCI platelets with 100 nM PGE1 (a stable probe of PGI2) inhibited the release of the mitogens by 90% (P < 0.001), with no effect on SCI platelets. Scatchard analysis of prostaglandin E1 (PGE1) binding showed a 70% decrease of PGI2 receptors on the SCI platelet surface. Treatment of SCI platelets with insulin or Ca2+ channel blockers restored the PGI2-receptor number and "normalized" the inhibition of PDGF release and thrombin generation by PGI2.

Demonstration of a novel circulating anti-prostacyclin receptor antibody

Although coronary artery disease (CAD) is appreciated to be accelerated in patients with chronic spinal cord injury (SCI), the underlying mechanism of CAD in SCI remains obscure. We have recently shown that platelets from subjects with SCI develop resistance to the inhibitory effect of prostacyclin (PGI2) on the platelet stimulation of thrombin generation. The loss of the inhibitory effect was due to the loss of high-affinity prostanoid receptors, which may contribute to atherogenesis in SCI. Incubation of normal, non-SCI platelets in SCI plasma (n = 12) also resulted in the loss of high-affinity binding of PGI2 (Kd1 = 9.1 +/- 2.0 nM; n1 = 170 +/- 32 sites per cell vs. Kd1 = 7.2 +/- 1.1 nM; n1 = 23 +/- 8 sites per cell), with no significant change in the low-affinity receptors (Kd2 = 1.9 +/- 0.1 microM; n2 = 1,832 +/- 232 sites per cell vs. Kd2 = 1. 6 +/- 0.1 microM; n2 = 1,740 +/- 161 sites per cell) as determined by Scatchard analysis of the binding of [3H]PGE1. The loss of high-affinity PGI2 binding led to the failure of PGI2 to inhibit the platelet-stimulated thrombin generation. The increase of cellular cyclic AMP level, mediated through the binding of PGI2 to low-affinity receptors in platelets, was unaffected in SCI platelets. PAGE and immunoblot of SCI plasma showed the presence of an IgG band, which specifically blocked the binding of [3H]PGE1 to the high-affinity PGI2 receptors of normal platelets. PAGE of the reduced IgG band, the amino acid sequence of the novel band as a heavy chain of IgG that inhibits the binding of [3H]PGE1 to the high-affinity platelet PGI2 receptor, demonstrates that the specific recognition and inhibition of high-affinity PGI2 binding to platelets was due to an anti-prostacyclin receptor antibody present in SCI plasma.