Myocardial neutrophil infiltration, lipid peroxidation, and antioxidant activity after coronary artery thrombosis and thrombolysis

2022 Update of the Consensus on the Rational Use of Antithrombotics and Thrombolytics in Veterinary Critical Care (CURATIVE) Domain 6: Defining rational use of thrombolytics

OBJECTIVES

To systematically review available evidence and establish guidelines related to the use of thrombolytics for the management of small animals with suspected or confirmed thrombosis.

DESIGN

PICO (Population, Intervention, Control, and Outcome) questions were formulated, and worksheets completed as part of a standardized and systematic literature evaluation. The population of interest included dogs and cats (considered separately) and arterial and venous thrombosis. The interventions assessed were the use of thrombolytics, compared to no thrombolytics, with or without anticoagulants or antiplatelet agents. Specific protocols for recombinant tissue plasminogen activator were also evaluated. Outcomes assessed included efficacy and safety. Relevant articles were categorized according to level of evidence, quality, and as to whether they supported, were neutral to, or opposed the PICO questions. Conclusions from the PICO worksheets were used to draft guidelines, which were subsequently refined via Delphi surveys undertaken by the Consensus on the Rational Use of Antithrombotics and Thrombolytics in Veterinary Critical Care (CURATIVE) working group.

RESULTS

Fourteen PICO questions were developed, generating 14 guidelines. The majority of the literature addressing the PICO questions in dogs is experimental studies (level of evidence 3), thus providing insufficient evidence to determine if thrombolysis improves patient-centered outcomes. In cats, literature was more limited and often neutral to the PICO questions, precluding strong evidence-based recommendations for thrombolytic use. Rather, for both species, suggestions are made regarding considerations for when thrombolytic drugs may be considered, the combination of thrombolytics with anticoagulant or antiplatelet drugs, and the choice of thrombolytic agent.

CONCLUSIONS

Substantial additional research is needed to address the role of thrombolytics for the treatment of arterial and venous thrombosis in dogs and cats. Clinical trials with patient-centered outcomes will be most valuable for addressing knowledge gaps in the field.

Inhibitory Effect of Lactobacillus delbrueckii subsp. bulgaricus KSFY07 on Kappa-Carrageenan-Induced Thrombosis in Mice and the Regulation of Oxidative Damage

A mouse thrombosis model was established by kappa-carrageenan to observe the inhibitory effect of Lactobacillus delbrueckii subsp. bulgaricus KSFY07 (LDSB-KSFY07) on thrombosis and the oxidative stress response. Mouse serum, liver tissue-related indicators, and intestinal microbial composition were measured by examining the expression of microbes in mouse faeces using a biochemical kit, slice observations, and quantitative polymerase chain reaction (qPCR) experiments. The results showed that LDSB-KSFY07 effectively reduced the degree of black tail in thrombotic mice, increased activated partial thromboplastin time (APTT), and decreased thrombin time (TT), fibrinogen (FIB), and prothrombin time (PT) in thrombotic mice. LDSB-KSFY07 was also able to reduce malondialdehyde (MDA) levels and increase superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) levels in the serum and liver tissues of thrombotic mice. Pathological observations showed that LDSB-KSFY07 reduced liver tissue lesions and tail vein thrombosis. Further, experimental results showed that LDSB-KSFY07 was able to upregulate the mRNA expression of copper/zinc-SOD (Cu/Zn-SOD), manganese-SOD, and GSH-Px in the liver tissue of thrombotic mice. Moreover, LDSB-KSFY07 was also able to downregulate the mRNA expression of NF-κB p65, intercellular cell adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin in tail vein vascular tissue. Meanwhile, LDSB-KSFY07 could raise plasminogen activator inhibitor-1 (PAI-1) mRNA expression and reduce tissue plasminogen activator (t-PA) expression in heart and tail vein vascular tissues of thrombotic mice. A mouse faeces examination revealed that LDSB-KSFY07 could also upregulate Bacteroides, Lactobacterium, and Bifidobacterium microbial expression and downregulate Firmicutes expression in the gut. These results indicate that LDSB-KSFY07 was able to inhibit mouse thrombosis and reduce liver oxidative stress damage in thrombus mice and show that high concentrations of LDSB-KSFY07 provided a better response similar to that of the drug heparin.

Early Effects of Simvastatin versus Atorvastatin on Oxidative Stress and Proinflammatory Cytokines in Hyperlipidemic Subjects

The authors investigated the time-dependent action of atorvastatin and simvastatin on oxidative stress and cytokine levels immediately after the start of treatment. These factors play a role in endothelial dysfunction. Hyperlipidemic patients (n=132) were assigned to treatment with 40 mg atorvastatin, 40 mg simvastatin, or placebo. Blood samples were taken before, 2 hours, 24 hours, 7 days, and 3 weeks after the administration of the statin or placebo to evaluate serum concentrations of total peroxides (TP), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-a) and soluble intercellular vascular adhesion molecule 1 (sICAM 1). In the atorvastatin group the TP changes were significantly different at 2 hours and 24 hours (p=0.005), whereas in the simvastatin group there was a gradual, more or less linear decline in TP until 7 days (p=0.006) and then a plateau. Simvastatin exhibited a faster statistically significant decrease over time in IL-6 and sICAM 1 levels (at 7 days, p=0.014 and p=0.001, respectively). TNF-a demonstrated a faster linear trend in the simvastatin group, but the significant effect appeared late (p=0.006). Both simvastatin and atorvastatin exerted early beneficial effects on oxidative stress, proinflammatory cytokines, and endothelial activation in hyperlipidemic subjects. These effects became significant 2 hours following the initiation of therapy.

Assessment of Oxidative DNA Damage by Alkaline Comet Assay in Human Essential Hypertension

The objective of the present study was to investigate the antioxidant status and the extent of oxidative DNA damage in lymphocytes and their relation with essential hypertension (EHT). A total of 100 South Indian subjects aged 30-65 were included for the study. Of these 50 were normotensive controls (group-1) with blood pressure ≥120/80 mm Hg, 50 were newly diagnosed (group-2) and were not on any antihypertensive drugs, but had systolic blood pressure ranging between 140 and 160 mmHg and diastolic blood pressure 95-100 mmHg and 50 newly diagnosed essential hypertensive patients underwent drug therapy for 1 year was considered as group-3. Enzymatic and non-enzymatic antioxidants significantly decreased and lymphocyte DNA damage was significantly increased in newly diagnosed hypertensive patients compared with control group. The major decrease in DNA damage and significant improvement in enzymatic and non-enzymatic antioxidants were observed after 1 year of antihypertensive therapy in treated group compared with newly diagnosed hypertensive patients. Total antioxidant status and lymphocyte DNA damage showed a strong negative correlation in all the three groups. Essential hypertension associated with oxidative stress which in turn causes genotoxic susceptibility to variety of disease including cancer. In the absence of DNA repair process and DNA checkpoint mechanisms, the genomic integrity is susceptible to extensive damage. In our study, increased oxidative DNA damage and decreased antioxidant levels were frequently observed in the newly diagnosed essential hypertensive patients, suggesting that oxidative stress is important in the pathogenesis of EHT. Therefore, the present study has additional clinical implication. Further investigations with large number of patients along with antioxidant supplement are highly warranted.

DNA damage and oxidative status in newly diagnosed, untreated, dipper and non-dipper hypertensive patients

DNA damage occurs more often in hypertensive patients than in non-hypertensive individuals. We sought to investigate lymphocyte DNA damage and total antioxidant status (TAS) levels in patients with dipper hypertension (DH) and non-dipper hypertension (NDH). Thirty-three patients with NDH (NDH group), 31 patients with DH (DH group) and 20 healthy volunteers (control group) were included in the study. Measurements from ambulatory blood pressure monitoring were obtained for all subjects. DNA damage was assessed in peripheral lymphocytes by comet assay, and plasma TAS levels were determined using an automated measurement method. The mean DNA damage value of the NDH group was higher than that of both the DH and control groups (P=0.002 and P<0.001, respectively). The mean DNA damage value of the DH group was higher than that of the control group (P<0.001). The mean TAS level of the NDH group was lower than that of both the DH and control groups (P=0.001 and P<0.001, respectively), and the mean TAS level of the DH group was lower than that of the control group (P<0.001). DNA damage was negatively associated with TAS level (r=-0.692, P<0.001) and positively associated with high sensitive c-reactive protein level (r=0.315, P=0.012). DNA damage increased in the NDH group compared with both the DH group and control group. This condition may be related to increased oxidative stress in the NDH group compared with the DH and control groups.

Hydrogen sulfide in the mammalian cardiovascular system

For more than a century, hydrogen sulfide (H(2)S) has been regarded as a toxic gas. This review surveys the growing recognition of the role of H(2)S as an endogenous signaling molecule in mammals, with emphasis on its physiological and pathological pathways in the cardiovascular system. In biological fluids, H(2)S gas is a weak acid that exists as about 15% H(2)S, 85% HS(-), and a trace of S(2-). Here, we use "H(2)S" to refer to this mixture. H(2)S has been found to influence heart contractile functions and may serve as a cardioprotectant for treating ischemic heart diseases and heart failure. Alterations of the endogenous H(2)S level have been found in animal models with various pathological conditions such as myocardial ischemia, spontaneous hypertension, and hypoxic pulmonary hypertension. In the vascular system, H(2)S exerts biphasic regulation of a vascular tone with varying effects based on its concentration and in the presence of nitric oxide. Over the past decade, several H(2)S-releasing compounds (NaHS, Na(2)S, GYY4137, etc.) have been utilized to test the effect of exogenous H(2)S under different physiological and pathological situations in vivo and in vitro. H(2)S has been found to promote angiogenesis and to protect against atherosclerosis and hypertension, while excess H(2)S may promote inflammation in septic or hemorrhagic shock. H(2)S-releasing compounds and inhibitors of H(2)S synthesis hold promise in alleviating specific disease conditions. This comprehensive review covers in detail the effects of H(2)S on the cardiovascular system, especially in disease situations, and also the various underlying mechanisms.

Urinary 8-OHdG: A marker of oxidative stress to DNA and total antioxidant status in essential hypertension with South Indian population

Establishment of non-invasive urinary biomarker for the early prediction of essential hypertension (EH) is important. We evaluated whether estimation of urinary DNA, serves as a marker to predict the extent of cellular oxidative stress in essential hypertension. A total of 180 South Indian subjects aged 30-65 were recruited for the study. Of these hypertensive subjects investigated, 30 were newly diagnosed and were not on any antihypertensive drugs, but had systolic blood pressure 140-160 mmHg and diastolic blood pressure 95-100 mmHg and 75 hypertensive patients who already on drug therapy for one year and 75 were South Indian normotensive healthy controls with blood pressure ≤ 120/80 mmHg. The 8-OHdG level in urine was significantly increased in hypertensive patients (both newly diagnosed and who already on drug therapy) compared with control group. The significant increase in 8-OHdG was observed in newly diagnosed hypertensive patients compared with hypertensive patients who already on drug therapy. There was a significant decrease in serum TAS value in essential hypertensive group when compared to control group. The urinary 8-OHdG was independently correlated with serum TAS. Decreased TAS levels, which reflect to increased oxidative stress, may be the reason of increased urinary 8-OHdG in South Indian hypertensive patients. Our preliminary data suggest that the competitive ELISA for 8-OHdG appears to be a simple method for quantifying the extent of oxidative stress.

Oxidative stress parameters in erythrocytes of post-reperfused patients with myocardial infarction

The effect of reperfusion of patients with myocardial infarction on the levels of some anti-oxidant enzymes, total thiols, malondialdehyde formation in erythrocytes and plasma ascorbate levels have been investigated. Significantly decreased activities of catalase and superoxide dismutase and decreased levels of total thiols in RBC's and ascorbic acid in plasma suggest that reperfusion of the infarcted myocardium leads to oxidative stress conditions wherein anti-oxidant mechanisms become less effective in coping with the oxidative insult. This view is further supported by the observation that in the post reperfused patients there is a highly significant enhancement in the levels of malondialdehyde.

Comparison of serum lipid compositions, lipid peroxide, alpha-tocopherol and lipoproteins in captive marine mammals (bottlenose dolphins, spotted seals and West Indian manatees) and terrestrial mammals

Concentrations of serum lipid components, lipid peroxide (LPO) and alpha-tocopherol and electrophoretic patterns of lipoproteins in serum samples obtained from captive marine mammals and terrestrial mammals were compared. Serum concentrations of total cholesterol, free fatty acid, and phospholipid in fish-eating animals were significantly higher than those in manatees and cows. Serum LPO and alpha-tocopherol concentrations in the fish-eating animals were also significantly higher than those in manatees, cows and dogs. Different patterns of densitometric scans of low density lipoprotein (LDL) and a significantly lower percentage of LDL were demonstrated in the dolphins compared with the seals, cow and dogs. The concentration of LPO was significantly correlated with triglyceride and phospholipid concentrations in serum from the dolphins. These results suggest that triglyceride and phospholipid are susceptible to oxidative reaction in fish-eating animals. Evaluation of serum lipids, LPO and alpha-tocopherol concentrations is needed for nutritional husbandry for fish-eating animals.

Lymphocyte DNA damage is associated with increased aortic intima-media thickness

OBJECTIVES

To investigate whether there is an association between lymphocyte DNA damage and aortic intima-media thickness (IMT).

METHODS

We studied 70 patients (mean age: 41.6+/-10 years) who underwent transesophageal echocardiography for various indications. Four different grades were determined according to intima-media thickness (IMT) of thoracic aorta measured by transesophageal echocardiography. DNA damage was assessed by alkaline single cell electrophoresis (comet) assay in peripheral lymphocytes. Plasma level of total antioxidant status (TAS) was determined by using automated measurement method. High sensitive C-reactive protein and other biochemical markers were studied in all subjects.

RESULTS

The major increase in lymphocyte DNA damage was observed in patients with grade 4 IMT when compared with other groups (p<0.001, for all). Lymphocyte DNA damage of patients with grade 1 IMT was also lower than patients with grade 2 IMT (p=0.013) and patients with grade 3 IMT (p<0.001). Lymphocyte DNA damage of patients with grade 2 IMT was found at low level compared with patients with grade 3 IMT (p=0.012) as well. In multiple linear regression analysis, IMT was independently correlated with lymphocyte DNA damage (beta=0.515, p<0.001), TAS level (beta=-420, p<0.001), total cholesterol (beta=0.407, p<0.001) and LDL cholesterol level (beta=287, p=0.020).

CONCLUSION

Lymphocyte DNA damage may be an independent predictor for the grade of thoracic IMT, and may play a role in pathogenesis of thoracic atherosclerosis besides TAS and cholesterol levels.

Relationship between left ventricle geometric patterns and lymphocyte DNA damage in patients with untreated essential hypertension

OBJECTIVE

To investigate the association between different the left ventricle (LV) geometric patterns and lymphocyte DNA damage in patients with hypertension (HT).

METHODS

We studied 84 patients (50.0+/-6.1, years) with HT and 24 healthy control subjects (48.6+/-3.3, years). Four different geometric patterns were identified in patients according to LV mass index and relative wall thickness. Peripheral lymphocyte DNA damages and plasma levels of total antioxidant status (TAS) were determined in all subjects.

RESULTS

DNA damage was increased in hypertensive patients compared with control group (p=0.001). The major increase in DNA damage was observed in concentric hypertrophic geometric pattern compared with all other geometric patterns (p<0.001, for all). In multiple linear regression analysis, lymphocyte DNA damage was independently correlated with only TAS (beta=-0.444, p<0.001), but not LV geometry (p>0.05).

CONCLUSION

The major increase in lymphocyte DNA damage was observed in concentric hypertrophic geometric pattern. This result may be related to increased oxidative stress.

Adenosine A2A agonists in development for the treatment of inflammation

Extracellular adenosine binds specifically to a family of four G protein-coupled cell-surface adenosine receptors (ARs). As the activation of the A2AAR modulates the activity of multiple inflammatory cells including neutrophils, macrophages and T lymphocytes, the receptor is considered to be a promising pharmacological target for the treatment of inflammatory disorders. Although adenosine binds nonselectively to all four AR subtypes, A2AAR selective agonists have been developed and shown to inhibit multiple manifestations of inflammatory cell activation including superoxide anion generation, cytokine production and adhesion molecule expression. A2AAR agonists are also vasodilators, but the inhibition of inflammation occurs at low doses that produce few or no cardiovascular side effects. Therefore, the selective activation of the A2AAR by these compounds holds significant potential in the treatment of inflammation.

Cardioprotective effects of rosiglitazone are associated with selective overexpression of type 2 angiotensin receptors and inhibition of p42/44 MAPK

Current evidence points to renin-angiotensin system as a key mediator in ischemia-reperfusion injury. Rosiglitazone, a peroxisome proliferator-activated receptor-gamma (PPAR-gamma) ligand, has recently been shown to confer cardioprotection against ischemia-reperfusion in animal models. We sought to examine the expression of ANG II receptors during PPAR-gamma-mediated cardioprotection. Male Sprague-Dawley rats (nondiabetic) were fed either regular rat chow (control diet group, n = 9) or rosiglitazone-rich diet (rosiglitazone-rich diet group, n = 9) and were subjected to 1 h of myocardial ischemia followed by 1 h of reperfusion. A third group of rats had only thoracotomy and pericardiotomy and served as a sham control group (n = 9). Hemodynamics, infarct size, and expression of ANG II type 1 and type 2 receptors (AT1 and AT2) were measured in all groups. There was a 58% reduction of infarct size in the rosiglitazone-rich diet group (P < 0.01 vs. control diet group). Increased myocardial expression of AT(1) receptors in the ischemic-reperfused myocardium was attenuated in the rosiglitazone-rich diet group (P < 0.05 vs. control diet group). Importantly, myocardial AT2 mRNA and protein expression were significantly increased (by >100-fold) in the rosiglitazone-rich diet group (P < 0.05). These changes were accompanied by inhibition of p42/44 MAPK in the rosiglitazone-rich diet group, while the Akt1 expression, believed to mediate insulin sensitization, remained similar in all three groups. The cardioprotective effects of rosiglitazone against myocardial ischemia-reperfusion injury are independent of its insulin-sensitizing properties and are associated with significant overexpression of AT2 receptors along with inhibition of p42/44 MAPK.

Serum lipid peroxide and alpha-tocopherol concentrations and superoxide dismutase activity in captive bottle-nosed dolphins

OBJECTIVE

To evaluate serum lipid peroxide (LPO) and alpha-tocopherol concentrations and superoxide dismutase (SOD) activity in captive bottle-nosed dolphins and to evaluate effects of storage on production of LPO in various marine fish.

ANIMALS

16 bottle-nosed dolphins.

PROCEDURE

8 dolphins (group A) were fed chub mackerel and herring (high fat) and arabesque greenling and banded blue-sprat (low fat); the other 8 dolphins (group B) were fed chub mackerel and Pacific saury (high fat) and shishamo smelt and Japanese horse mackerel (low fat). Each group had been on these respective diets for 3 years. Serum LPO and alpha-tocopherol concentrations, serum SOD activity, and superoxide production by neutrophils were measured. All types of marine fish were frozen at -20 C for 6 months, and concentrations of LPO were measured at various time points.

RESULTS

Serum LPO concentrations in group-A dolphins were significantly higher than those in group B. Serum alpha-tocopherol concentrations and SOD activity in group A were significantly lower than those in group B. A significant negative correlation was found between serum LPO and alpha-tocopherol concentrations in all 16 dolphins. The LPO concentrations in mackerel and herring fed to group-A dolphins were higher than those of other fish. Concentrations of LPO in herring stored for 3 and 6 months at -20 C were higher than those in herring before freezing and in herring stored for 1 month.

CONCLUSIONS AND CLINICAL RELEVANCE

Serum LPO and alpha-tocopherol concentrations in captive bottle-nosed dolphins may be strongly influenced by high amounts of polyunsaturated fatty acid and LPO found in marine fatty fishes. High concentrations of serum LPO, as found in group-A dolphins, were associated with decreased antioxidative states. Monitoring of serum LPO and alpha-tocopherol concentrations and serum SOD activity may be useful for the management of captive marine mammals.

Modulation of myocardial SOD and iNOS during ischemia-reperfusion by antisense directed at ACE mRNA

Renin-angiotensin system (RAS) is involved in the regulation of superoxide dismutase (SOD) and nitric oxide (NO) equilibrium, and its modulation protects hearts from ischemic dysfunction. We examined the effect of a new antisense-oligodeoxynucleotides (AS-ODNs) directed at ACE mRNA on SOD and iNOS expression during myocardial ischemia. Sprague-Dawley rats were treated with saline, AS-ODNs, or inverted-ODNs (IN-ODNs), given with liposome DOTAP/DOPE. Hearts were excised and subjected to 25 min of ischemia followed by 30 min of reperfusion. Ischemia-reperfusion in saline-treated hearts resulted in a decrease in the expression of SOD and an increase in the expression of inducible NOS (iNOS) genes concurrently with myocardial dysfunction. AS-ODNs, but not IN-ODNs, protected hearts against functional deterioration, and upregulated SOD expression and inhibited the expression of iNOS. ACE protein expression was decreased in the rat hearts of the AS-ODNs-treated group, but not in the IN-ODNs group. Thus manipulation of RAS with AS-ODNs directed at ACE mRNA can ameliorate cardiac dysfunction and modulate expression of SOD and iNOS at genomic level.

Reperfusion injury after focal myocardial ischaemia: polymorphonuclear leukocyte activation and its clinical implications

The only way to rescue ischaemic tissue is to re-instate the oxygen supply to the tissue. However reperfusion of the ischaemic area not only oxygenates the tissue but also initiates a cascade of processes, which may in some cases result in temporary dysfunction of the myocardium. In order to devise protective measures, it is essential to understand the mechanisms and the triggers of this reperfusion phenomenon. In this review we will mainly focus on the inflammatory response caused by reperfusion. We will cover the different steps of polymorphonuclear leukocyte activation and will briefly discuss the molecular biology of the receptors involved. The currently used pharmacological medications in acute cardiology will be reviewed and in particular their actions on polymorphonuclear leukocyte activation, adhesion and degranulation. This review is a compilation of the current knowledge in the field and the therapeutic progress in the prevention of reperfusion injury made today.

Diet enriched with procyanidins enhances antioxidant activity and reduces myocardial post-ischaemic damage in rats

Aim of this work was to study the efficacy of procyanidins from Vitis vinifera seeds, a standardized mixture of polyphenol antioxidants, on cardiac mechanics following ischemia/reperfusion stunning in the rat, after 3 weeks supplementation. Young and aged male rats were fed a diet enriched with procyanidins complexed (1:3 w/w) with soybean lecithin (2.4%); control animals (CTR-young and CTR-aged) received an equal amount of lecithin and 2 additional groups of animals the standard diet. At the end of the treatment, the total plasma antioxidant defense (TRAP), vitamin E, ascorbic acid and uric acid were determined in plasma and the hearts from all groups of animals subjected to moderate ischemia (flow reduction to 1 ml/min for 20 min) and reperfusion (15 ml/min for 30 min). In both young and aged rats supplemented with procyanidins the recovery of left ventricular developed pressure (LVDP) at the end of reperfusion was 93% (p < 0.01) and 74% (p < 0.01) of the preischemic values and the values of coronary perfusion pressure (CPP) were maintained close to those of the preischemic period. Also creatine kinase (CK) outflow was restrained to baseline levels, while a 2-fold increase in prostacyclin (6-keto-PGF1alpha) in the perfusate from hearts of young and aged rats was elicited during both ischemia and reperfusion. In parallel, procyanidins significantly increased the total antioxidant plasma capacity (by 40% in young and by 30% in aged rats) and the plasma levels of ascorbic acid, while tend to reduce vitamin E levels; no significant differences were observed in uric acid levels. The results of this study demonstrate that procyanidins supplementation in the rat (young and aged) makes the heart less susceptible to ischemia/reperfusion damage and that this is positively associated to an increase in plasma antioxidant activity.

Effect of cocaine on cardiac biochemical functions

The role of cocaine in cardiac ischemia and subsequent reversible and irreversible pathologic changes is well established. Nevertheless, the mechanisms leading to cardiac injury and irreversible cellular changes remain elusive. Reactive oxygen species (ROSs) are the critical mediators of cellular damage during ischemia-reperfusion. To explore the response of cardiac oxidative stress parameters to intravenous (i.v.) And intraperitoneal (i.p.) cocaine exposure, cardiac total glutathione (GSH, GSSG), malonaldialdehyde (MDA), Mn-superoxide dismutase (Mn-SOD), catalase (CAT), GSH-peroxidase (GSH-px), and GSH s-transferase (GST) were measured, along with biochemical and histologic markers indicative of cardiac injury. Repeated i.p. cocaine exposure produced significant impairment in cardiac integrity, demonstrated by increased circulating lactate (2.4-fold; p < 0.0001), creatine kinase (2.2-fold; p < 0.0001), and creatinine levels (1.7-fold; p < 0.0001). Infiltration of neutrophils into myocardial cavities also was evident. These changes paralleled increases in cardiac MDA (25%; p < 0.04), GSSG (55%; p < 0.001), protein carbonyls (23%; p < 0.05), and Mn-SOD (23%; p < 0.05) levels, indicative of oxidative stress, decreases in GSH (35%; p < 0.01), adenosine triphosphate (ATP; 26%; p < 0.04), GSH-px (28%; p < 0.03), CAT (32%; p < 0.01), and GST (50%; p < 0.001) levels. Intravenous cocaine administration also had similar effects on cardiac oxidative stress measures. In conclusion, our data indicate that cocaine administration compromised the heart's antioxidant defense system.

Vitamins C and E prolong time to arterial thrombosis in rats

To examine the modulation of arterial thrombosis by vitamins C and E, Sprague-Dawley rats were fed nonpurified diet, or diet mixed with vitamin C [100 mg/(kg body weight.d)], vitamin E [100 mg/(kg.d)] or both vitamins C and E [each 100 mg/(kg.d)], for a period of 9-19 d (mean 15 d). An occlusive aortic thrombus was created by application of a Whatman filter soaked in 1 mol/L FeCl3. Both vitamins C and E and their combination decreased platelet aggregation and delayed time to occlusive thrombus formation (P < 0.05 vs. control). Vitamins C and E decreased arterial superoxide generation (P < 0.05 vs. control). Interestingly, vitamin E also increased endogenous superoxide dismutase activity (SOD) and protein expression in aortic tissues (P < 0.05 vs. control). The combination of vitamins C and E was not superior to each vitamin alone with regard to effect on time to thrombus formation, but it was more potent with regard to platelet inhibition. The increase in endogenous antioxidant activity by vitamin E is an intriguing observation. This study shows that the antioxidant vitamins C and E have important effects on platelet aggregation, SOD activity, superoxide generation and thrombus formation.

Pharmacokinetics and pharmacodynamics of SM-20302, a GPIIb/IIIa receptor antagonist, in anesthetized dogs

We examined the pharmacokinetic and pharmacodynamic properties of SM-20302, a GPIIb/IIIa receptor antagonist, in anesthetized dogs. SM-20302 was administered intravenously in doses of 30 (n=2), 100 (n=4), 300 (n=4), and 1,000 microg/kg (n=4). The half-life of the initial phase was 4 min, and that of the terminal phase was 162-209 min. SM-20302 produced a dose-dependent increase in the initial plasma concentration and the area under concentration-time curve but did not alter the volume of distribution, mean residence time, or plasma clearance. Plasma clearance for SM-20302 ranged from 6.58 to 9.73 ml/min/kg. All doses of SM-20302 inhibited (> or =90%) the ex vivo platelet aggregation induced by adenosine diphosphate (ADP) or arachidonic acid (AA) in citrated platelet-rich plasma (cPRP). In heparinized PRP (hPRP), a dose-dependent (44-89%) inhibition was observed. By using a sigmoid Emax model, the in vivo median inhibitory concentration (IC50) for SM-20302 was estimated to be 14-19 ng/ml in cPRP and 79-89 ng/ml in hPRP. To validate the calculated parameters, an infusion regimen was designed for the prevention of coronary artery thrombosis. Infusion of SM-20302 produced 64-67% inhibition of platelets in hPRP and maintained vessel patency despite vessel wall injury. The results suggest that SM-20302 exhibits linear pharmacokinetics and that its ability to inhibit platelet aggregation in hPRP may correlate more accurately with its in vivo antithrombotic efficacy.

Effects of exercise-induced oxidative stress on nitric oxide release and antioxidant activity

This study shows that acute exercise in healthy subjects is a modest oxidative stress, which may be related to an increase in antioxidant activity and down-regulation of nitric oxide formation.

Priming of neutrophils after elective percutaneous transluminal coronary angioplasty is unrelated to accompanying brief myocardial ischemia

OBJECTIVE

The purpose of this study was to investigate the effect of brief myocardial ischemia and vascular trauma induced by elective percutaneous transluminal coronary angioplasty on in vivo 'priming' and activation of neutrophils.

PATIENTS AND METHODS

We studied 16 patients undergoing elective coronary angioplasty for symptomatic coronary artery disease and a control group of seven patients undergoing diagnostic cardiac catheterization. Free radical production from purified neutrophils (Ficoll-Hypaque density gradient method) was measured indirectly by the chemiluminescence method. Myocardial ischemia during balloon inflation was assessed by serial lactate determinations from coronary sinus and arterial blood. The degree of transient angioplasty-related myocardial ischemia was related to the oxidative response of activated neutrophils.

RESULTS

Mean (+/-S.E.M.) oxidative response, i.e. the lucigenin- and luminol-enhanced-chemiluminescence (counts per minute) of neutrophils sampled from the coronary sinus increased significantly after percutaneous transluminal coronary angioplasty (Lucigenin-chemiluminescence: pre-angioplasty 3.69+/-0.64x10(5) vs. post-angioplasty 7.08+/-1.2x10(5), P<0.01; Luminol-chemiluminescence: pre-angioplasty 2.81+/-0.67x10(6) vs. post-angioplasty 5.2+/-0.92x10(6), P<0.01). Twelve of 16 patients developed transient cardiac lactate production (mean coronary sinus lactate excess: +0.12 mmol/l) and three disclosed a lactate extraction ratio <10%, both suggestive of myocardial ischemia. However, there was no correlation between the cardiac lactate production and the increased oxidative response after coronary angioplasty (r2 (Lucigenin-chemiluminescence)=0.02, n.s.; r2 (Luminol-chemiluminescence)=0.06, n.s.).

CONCLUSION

'Priming' of neutrophils, as reflected by increased oxidative response, is likely to occur after coronary angioplasty, but not after the angiographic procedure itself. However, 'priming' seems to be unrelated to the transient brief period of myocardial ischemia and rather depends on an alternative mechanism.

Effects of lecithinized superoxide dismutase on traumatic brain injury in rats

Only small amounts of superoxide dismutase (SOD) are present in the extracellular space to scavenge excess amounts of superoxide anions (02-) released after traumatic brain injury (TBI). Experiments were performed in rats with cerebral contusion produced by weight-drop technique. We investigated the effects of exogenous lecithinized SOD (PC-SOD) on accumulation of 02- produced in our model, by measuring the level of SOD activity (using the NBT-reducing method) and the expression of copper, zinc-SOD (Cu, Zn-SOD) mRNA (by Northern blot analysis). As determined by tissue-specific gravity, administration of PC-SOD reduced brain edema in the periphery of the lesion 6 h after contusion. SOD activity increased in the peripheral region at 30 min after contusion, but returned to normal levels at 6 h after TBI. Administration of PC-SOD increased SOD activity up to 6 h after TBI. The expression of Cu, Zn-SOD mRNA increased in the core region, peripheral portion, and contralateral hemisphere up to 6 h after TBI, then was suppressed in all three regions by PC-SOD. Our results confirm the important role of 02- in the development of brain edema after TBI and indicate that PC-SOD diminishes brain edema through a protective effect against 02-.

Reperfusion injury in the endotoxin-treated rat heart: reevaluation of the role of nitric oxide

1. The role of nitric oxide (NO) in ischaemia-reperfusion injury to the heart continues to be debated. 2. The role of NO released during endotoxemia on myocardial reperfusion injury was examined in rats given saline or lipopolysaccharide (LPS, 10 mg. kg-1). 3. Aortic rings from LPS-treated rats showed a markedly decreased contractile response to both noradrenaline (NA) and U46619, and a diminished relaxation response to acetylcholine, thrombin and aggregating platelets. Treatment of rat aortic rings from LPS-treated rats with the NO synthesis inhibitor N omega-nitro-L-arginine (L-NOARG) reversed the diminished contractile response to NE and U46619. 4. Before ischaemia-reperfusion, baseline force of cardiac contraction (FCC) and coronary perfusion pressure (CPP) were lower and coronary flow was higher in hearts from LPS-treated rats (all P < 0.05 vs. saline-treated group). Treatment of hearts from LPS-treated rats with L-NOARG increased baseline FCC and CPP. 5. After ischaemia-reperfusion, hearts from saline-treated rats showed a 36 +/- 5% fall in FCC, a 38 +/- 6% rise in CPP and a 38 +/- 5% fall in coronary flow, whereas hearts from LPS-treated rats revealed only a 16 +/- 9% fall in FCC, a 10 +/- 3% rise in CPP and a 20 +/- 4% fall in coronary flow (all P < 0.05 vs. changes in saline-treated group). Fewer hearts from LPS-treated rats developed reperfusion arrhythmias (6% vs. 60% hearts from saline-treated rats, P < 0.02). Myocardial superoxide dismutase activity was higher in the LPS-treated group (P < 0.05). 6. NO synthesis, measured as formation of nitrite, was higher (P < 0.05) in cardiac and aortic tissues from LPS-treated rats. Prostacyclin (PGI2) release in coronary effluent was greater in LPS-treated rat hearts (P < 0.05 vs. saline-treated rats). 7. Thus LPS-treated hearts demonstrate a basal decrease in FCC and coronary vascular resistance. These hearts demonstrate a modest protection from reperfusion injury. Induction of NO synthesis, and possibly PGI2 release, may underlie cardioprotection from ischaemia-reperfusion.

Manganese-based superoxide dismutase mimetics inhibit neutrophil infiltration in vivo

In a previous study (Hardy et al. (1994) J. Biol. Chem. 269, 18535-18540), we observed that the manganese-based superoxide dismutase mimetic Mn(II)-dichloro(1,4,7,10,13-pentaazacyclopentadecane) (MnPAM) inhibited neutrophil-mediated cell injury in vitro. We have extended these studies with the low molecular weight superoxide dismutase mimic to evaluate the role of superoxide in neutrophil-mediated tissue injury in vivo. In a dose-dependent manner, MnPAM inhibited colonic tissue injury and neutrophil accumulation into the colonic tissue induced by the intracolonic instillation of dilute aqueous acetic acid in mice. Tissue injury was assessed by visual and histological analysis. Neutrophil infiltration was determined by tissue myeloperoxidase activity and confirmed by histological analysis. Two novel Mn(II) dichloro complexes of the carbon-substituted macrocycles 2-methyl-1,4,7,10,13-pentaazacyclopentadecane (MnMAM) and 2-(2-methylpropyl)-1,4,7,10,13-pentaazacyclopentadecane (MnBAM) effectively catalyzed the dismutation of superoxide with catalytic rate constants (kcat) of 3. 31 x 10(7) M-1 s-1 and 1.91 x 10(7) M-1 s-1, respectively, as determined by stopped-flow kinetic analysis at pH 8.1 and 21 degrees C. The superoxide dismutase mimetics MnMAM and MnBAM also attenuated dilute aqueous acetic acid-induced tissue injury and neutrophil infiltration into colonic tissue; however, two Mn(II) complexes that had little or no detectable SOD activity (kcat </= 0.1 x 10(7) M-1 s-1), specifically the Mn(II) dichloro complexes of 1,4,7,10,13-pentaazacyclohexadecane and 1,4,7,11,14-pentaazacycloheptadecane, failed to inhibit the colonic tissue injury or infiltration of neutrophils in mice treated intracolonically with dilute aqueous acetic acid. These results are consistent with a proinflammatory role for superoxide in the mediation of neutrophil infiltration in vivo.

Effects of lecithinized superoxide dismutase on rat spinal cord injury

Although superoxide dismutase (SOD) has been reported to promote functional recovery in ischemic spinal cord injury, it presents many difficulties in practical use primarily due to its short half-life in vivo and low tissue affinity. In this study, we investigated the effects of a new type of SOD, a lecithinized superoxide dismutase (PC-SOD), on motor disturbances, spinal cord edema, levels of myeloperoxidase (MPO), and spinal cord blood flow (SCBF) after spinal cord injury (SCI) in rats. PC-SOD is reported to show a delayed plasma disappearance in vivo in rats and has a higher affinity for vascular endothelium cells, neutrophils, and other cells than unmodified SOD. PC-SOD (4000 units/kg), unmodified SOD (4000 units/kg), or vehicle was injected intravenously 30 min after SCI. Four hours after SCI, SOD activities in spinal cord tissue and plasma were significantly higher in the PC-SOD group than in the unmodified SOD group. In the PC-SOD-treated rats, motor function was significantly better than in the other 2 groups of rats. PC-SOD significantly suppressed MPO activity, an indicator of neutrophils infiltration, in the spinal cord, at 4, 8, and 24 h after SCI, and spinal cord edema at 24 h after SCI. Moreover, the decrease of SCBF after SCI was less marked in the PC-SOD group. The present results suggest that lecithinization can improve the drug delivery of SOD to the spinal cord and PC-SOD may be an alternative pharmacological treatment for SCI.

A chemiluminescent detection of superoxide radical produced by adherent leucocytes to the subendothelium following thrombolysis: studies with a photochemically induced thrombosis model in the guinea pig femoral artery

Reocclusion following thrombolysis is a major limitation of thrombolytic therapy with recombinant tissue-type plasminogen activator (rt-PA) because denuded vessel wall exposed to blood following thrombolysis is a favourable surface for platelet and leucocyte deposition. We have applied a chemiluminescence technique to detect superoxide radical (0(-2)) produced by leucocytes adherent to the femoral artery 24 h after photochemically induced thrombogenesis in the guinea pig in vivo and subsequent thrombolysis by rt-PA. Intravenous administration of MCLA, a specific chemiluminescence reagent for detecting O(-2), markedly increased photon emission. the photon emission was markedly potentiated by phorbol myristate acetate and was suppressed by superoxide dismutase. Reocclusion 24 h after rt-PA induced thrombolysis was observed in 10 of 16 animals. Histological observations revealed extensive polymorphonuclear leucocytes adherent to the vessel wall at the site of thrombogenesis and thrombolysis. A higher level of 0(-2) could be detected from the arteries in which thrombolysis was induced compared with those without thrombolysis. Further, the level 0(-2) detected was greater in reoccluded arteries compared with those in which reflow was established. These observations suggest that 0(-2) is produced by adherent leucocytes at the site of thrombolysis and that leucocytes are involved in reocclusion after thrombolysis.

Superoxide dismutase activity as a predictor of myocardial reperfusion and salvage in acute myocardial infarction

We attempted to predict successful myocardial reperfusion and salvage in acute myocardial infarction (AMI) by using measurements of plasma superoxide dismutase (SOD), a plasma free-radical scavenger, activity. Forty-nine patients with AMI were studied within 6 hours of symptoms onset. In group 1 (n = 26), primary percutaneous transluminal coronary angioplasty (PTCA) was undertaken, and plasma SOD activity was measured for 8 hours by the nitrite method. Left ventricular (LV) angiography was assessed before and 3 months after PTCA by computer LV contraction analysis. In group 2 (n = 23), TPA was infused intravenously over a 60-minute period, and plasma SOD activity was measured before and immediately after TPA infusion. In group 1, occluded coronary arteries were successfully dilated in 24 of 26 patients, and plasma SOD activity increased from 3.20 +/- 0.17 microns/ml to 4.66 +/- 0.29 microns/ml at 1 hour after PTCA (p < 0.001), returning to the basal level by 8 hours after PTCA. Plasma SOD activity did not significantly change patients with unsuccessful PTCA or those with the no-reflow phenomenon. The maximal increase in plasma SOD activity was significantly correlated with the grade of improvement in LV contraction (r = 0.852, p < 0.001). In group 2, the sensitivity and specificity of predicting coronary recanalization was 86% and 89%, respectively. In conclusion, myocardial reperfusion and salvage in AMI can be predicted by changes in plasma SOD activity.