Effect of Tocopheryl Acetate on Maternal Cigarette Smoke Exposed Swiss Albino Mice Inbred Fetus.

INTRODUCTION: Cigarette smoking is worldwide problem which can be correlated with teratogenicity. Tocopheryl acetate plays as an antioxidant against the oxidative stress evolved by cigarette smoke exposure during pregnancy. AIM: To study the effect of maternal exposure to cigarette smoke and Tocopheryl acetate on fetuses of mice. MATERIALS AND METHODS: Pregnant mice randomly assigned to different groups (Group I (control), Group II (Tocopheryl acetate), Group III(soyabean oil used as vehicle for Tocopheryl acetate), Group IV (Cigarette smoke Exposed), Group V (Cigarette smoke exposed plus Tocopheryl acetate) and Group VI(Cigarette smoke exposed plus soyabean oil) were exposed to cigarette smoke 3 times a day for 20 minutes each time and Tocopheryl acetate with dose of 200mg/kg/day in 0.3ml of soyabean oil as vehicle orally through oral gavage from the 5th day of gestation to 15th day. RESULTS: Cigarette smoke exposed mice showed significant fetal weight loss, resorption, placental anomalies, severe growth retardation, venous congestion, haemorrhage, limbs defects and enphalocele. Negligible abnormalities were seen among the control and Tocopheryl acetate group. Cigarette smoke exposed group with Tocopheryl acetate exhibited weight gain among the fetus as well as no gross abnormalities. The oxidative stress was significantly increased by increasing Malondialdehyde (MDA) 293±81.57 µmol/mg (p<0.0001) and decreasing Superoxide Dismutase (SOD) 1.43 ± 0.23mg/ml, (p<0.0001) Reduced Glutathione (GR) 0.017±0.002mg/ml, (p<0.01) and Catalase (CAT) 0.248±0.005mg/ml, (p<0.0001). Tocopheryl acetate induced group significantly maintained the oxidative stress with all p <0.0001. CONCLUSION: It can be concluded that Tocopheryl acetate may have an ameliorating effect on the cigarette smoke during pregnancy on fetus.

Aging-associated endothelial dysfunction in humans is reversed by L-arginine.

OBJECTIVES: This study investigated the hypothesis that aging selectively impairs endothelium-dependent function, which may be reversible by administration of L-arginine. BACKGROUND: An impaired response to acetylcholine with aging has been demonstrated in humans. However, the mechanisms underlying this impaired response of the coronary microvasculature remain to be determined. METHODS: We infused the endothelium-independent vasodilators papaverine and glyceryl trinitrate (GTN) and the endothelium-dependent vasodilator acetylcholine (1,3,10 and 30 micrograms/min) into the left coronary artery of 34 patients (27 to 73 years old) with atypical chest pain, negative exercise test results, completely normal findings on coronary angiography and no coronary risk factors. Coronary blood flow was measured with an intracoronary Doppler catheter. The papaverine and acetylcholine infusions were repeated in 14 patients (27 to 73 years old) after an intracoronary infusion of L-arginine (160 mumol/min for 20 min). RESULTS: There was a significant negative correlation between aging and the peak coronary blood flow response evoked by acetylcholine (r = -0.73, p < 0.0001). However, there was no correlation to papaverine (r = -0.04, p = 0.82) and GTN (r = -0.24, p = 0.17). The peak coronary blood flow response evoked by acetylcholine correlated significantly with aging before L-arginine infusion (r = -0.87, p < 0.0001), but this negative correlation was lost after L-arginine infusion (r = -0.37, p = 0.19). CONCLUSIONS: The results suggest that aging selectively impairs endothelium-dependent coronary microvascular function and that this impairment can be restored by administration of L-arginine, a precursor of nitric oxide.

Direct thrombin inhibitors: novel antithrombotics on the horizon in the thromboprophylactic management of atrial fibrillation.

Antithrombotic agents have verified efficacy in reducing the thromboembolic risk associated with atrial fibrillation. This article focuses on the emergence of a new oral direct thrombin inhibitor, ximelagatran, into the arena of atrial fibrillation thromboprophylaxis. This review does not cover atrial fibrillation in the context of valvular heart disease. The efficacy of aspirin and warfarin will be discussed briefly.

Effect of locally applied tissue-type plasminogen activator on venous fibrinolytic activity: in vitro and in vivo investigations.

OBJECTIVES: The aim was to see if topically applied tissue-type plasminogen activator (tPA) would enhance the fibrinolytic activity of saphenous vein prepared before coronary artery surgery, persist in the vessel wall after perfusion, and reduce thrombus formation after vascular injury. METHODS: Varying doses of tPA were applied to the intimal surface of the saphenous vein obtained from patients before coronary artery surgery. After flushing, biopsies were incubated on fibrin plates and areas of lysis quantified. Samples treated with tPA (1 mg.ml-1) were perfused in vitro for 30 minutes. Fibrinolytic activity was assessed on fibrin plates and tPA activity (in tissue extract) measured with chromogenic assays. The effect of locally applied tPA on thrombus formation was quantified with a rat vena cava model based on vascular injury and stasis. RESULTS: Local application of 1 mg.ml-1 tPA enhanced fibrinolysis under static conditions [median (interquartile range) of diameter of lysis.mm-1 (n = 8 both groups), treated vein 16.5 (14.1-17.9), control 8.5 (5.75-10.37) (p < 0.05)]. This enhanced activity was retained after in vitro perfusion [median (interquartile range) of areas of lysis.mm-2 (n = 8 all groups), treated vein 170.8 (132.8-205.1), control (unperfused) 69.5 (45.2-87.6), perfused (untreated) 76.7 (58.3-98.9) (p < 0.01)]. Specific tPA activity in these samples was also increased (p < 0.05). Local application of tPA (1 mg.ml-1) to damaged rat vena cava reduced subsequent thrombus formation [median thrombus weight.mg-1 (interquartile range) (n = 8), tPA treated 2.5 (0.25-5.75), control 38.5 (32-43) (p < 0.001)]. CONCLUSIONS: Locally applied tPA enhances the fibrinolytic activity of damaged vessel wall, persists after perfusion, and reduces thrombus formation after vascular injury. This method of treating conduits before their use as vascular grafts merits further study to see if it is effective in reducing early graft thrombosis while maintaining systemic haemostasis.

Changes in vessel wall plasminogen activator activity and smooth muscle cell proliferation and activation after arterial injury.

OBJECTIVES: The aim was to examine changes in vessel wall fibrinolytic activity following angioplasty and to assess any relationship to changes in smooth muscle cell proliferation and activation. METHODS: Balloon angioplasty was performed to the iliac arteries of New Zealand White rabbits and vessel wall changes assessed at 2 h, 1 d, 7 d, 14 d, and 1 month postprocedure. Tissue-type (tPA) and urokinase-type (uPA) plasminogen activator activity was assessed using chromogenic substrate assays, while smooth muscle cell proliferation and activation was monitored using expression of proliferating cell nuclear antigen (PCNA) and of basic fibroblast growth factor (bFGF) respectively. RESULTS: Intimal thickening progressively increased up to 1 month. uPA activity increased at 2 h [1.94(SEM 0.19) v 1.59(0.05) U.mg-1 tissue for control vessels, P = 0.03], remained increased at 24 h, but by 7 d had decreased to below control levels and remained low. In contrast, tPA activity fell significantly at 2 h [0.9(0.3) v 1.96(0.13) micrograms.mg-1 tissue for control vessels, P = 0.03], remained low at 24 h, but by 7 d had reverted back to control levels [2.19(0.39) micrograms.mg-1]. PCNA positivity of the media increased at day 1, reached maximum on day 7 [16.9(5.1)% positively staining cells] before returning to baseline by 1 month. PCNA positivity of the intima first evident at day 7 [0.7(0.3)%], reached a maximum at day 14 [4.1(0.4)%]. bFGF expression increased early at 2 h [mean(SE) positively staining cells: 15.7(5.3)% v 11.2(4.8)% for control vessels] and continued to increase, reaching a maximum in the media at day 7 [59(8.6)%] and in the intima at day 14 [57.5(5.7)%]. CONCLUSIONS: Balloon injury produced an initial fall in tPA and rise in uPA activity. tPA increased back to control levels by 7 d, while uPA fell to below control levels at 7 d and 1 month. This would be compatible with a mechanism whereby acute injury suppressed tPA and upregulated uPA activity, with increased tPA activity acting as a marker for vessel repair.

A targeted antithrombotic conjugate with antiplatelet and fibrinolytic properties which reduces in vivo thrombus formation.

OBJECTIVE: Potent therapy that could be locally delivered to inhibit blood factor-vessel wall interaction and which would remain localised to the site of damage may avoid the side effects of systemic drugs in the treatment of disorders such as subacute thrombosis of saphenous vein grafts and intravascular stents. We therefore assessed the feasibility of developing a targeted antithrombotic conjugate by covalently cross-linking urokinase to a monoclonal antibody to platelet glycoprotein IIb/IIIa (M735) and a monoclonal antibody against damaged endothelium (P14G11). METHODS: Conjugation was carried out using N-succinimidyl-3-(2-pyridyldithio) propionate as the cross-linking reagent. The conjugate was assessed in vitro and in an in vivo model of thrombosis and local delivery. RESULTS: The conjugate formed, ATC(3), retained specificity for damaged endothelial cells and platelets and had urokinase activity of approximately 10,000 IU.mg-1 protein. Persistence of urokinase activity on binding to intact platelets and scratch damaged endothelial monolayer preparations was confirmed. Platelet aggregation studies (using ADP and collagen) revealed complete inhibition by ATC(3) at a dose of 5 micrograms.ml-1 while an unconjugated mixture of M735 (20 micrograms.ml-1), P14G11 (20 micrograms.ml-1), and urokinase (200 IU.ml-1) failed to inhibit completely platelet aggregation induced by ADP. In an in vivo model of thrombosis and vascular injury, local delivery of ATC(3) significantly reduced the weight of thrombus formed [median 13 mg (interquartile range 9-20)] compared to an unconjugated mixture of M735, P14G11 and urokinase [35 mg (28-45)] and urokinase alone [41 mg (33-55)]. CONCLUSIONS: It is possible to produce a targeted antithrombotic conjugate which retains activity of all its individual components.

Anti-thrombotic therapy for non-rheumatic atrial fibrillation.

Recent randomized trials of antithrombotic therapy in non-rheumatic atrial fibrillation have helped to clarify the benefits of warfarin and aspirin. Low-risk patients (normotensives aged < 60 with normal left ventricular function) have a small risk of thromboembolic events and are unlikely to benefit significantly from anticoagulants, but may benefit from aspirin with little increase in risk of bleeding. High-risk patients (> 75 years, impaired left ventricular function, previous thromboembolism and/or associated conditions such as hypertension and diabetes mellitus) have an increased risk of thromboembolism, and benefit from long-term anticoagulant therapy to a greater degree than with aspirin, although at a risk of increased bleeding complications.

Rate or rhythm control in persistent atrial fibrillation?

Atrial fibrillation (AF) is the most common sustained tachyarrhythmia encountered in clinical practice, with the majority of patients aged > 65 years. With an increasingly ageing population, the burden of AF in society continues to rise. One of the principal controversies in AF management is whether to control the ventricular rate and accept the underlying rhythm, or to attempt to achieve sinus rhythm. Until recently there were no clinical trial data directly comparing a rate versus rhythm strategy, and most physicians have opted for rhythm control, based on its theoretical benefits. We present an up-to-date evidence-based overview of the relative merits of rate versus rhythm control in AF, including data from five recent randomized trials. We draw conclusions from these studies and present evidence-based guidance on when to adopt which approach in routine clinical practice.

Therapeutic levels of nitroglycerin do not affect the uptake and release of heparin by endothelial cells in vitro.

Intravenous heparin and nitroglycerin are frequently given in combination to patients with acute coronary syndromes such as unstable angina and post myocardial infarction angina. Heparin is prescribed since it has been shown that intracoronary thrombus formation is important in the pathophysiology of these acute conditions. However, it has been demonstrated that intravenous nitroglycerin can interfere with the anticoagulant effect of heparin. The exact mechanism of the interaction is unknown but it has been suggested that there is a direct effect on plasma heparin characterised by a reduction in circulating plasma heparin levels. Heparin binds to the surface of endothelial cells in a process that is time dependent, reversible and exhibits saturation kinetics. A possible mechanism of the observed effects on the plasma heparin levels produced by nitroglycerin may be the altered handling of heparin by endothelial cells. We have investigated this further by assessing the effects of therapeutic doses of nitroglycerin on heparin uptake and release by endothelial cells, using 35S labelled heparin and human umbilical vein endothelial cell cultures.

Absence of a prothrombotic state in restenotic patients?

AIMS: To determine whether, in patients undergoing percutaneous transluminal coronary angioplasty (PTCA), there are prothrombotic markers indicating those with a predisposition to restenosis. METHODS: Venous blood samples were obtained from patients undergoing PTCA for chronic stable angina. Patients with restenotic lesions, conduit stenoses or occlusive lesions were not included in the study. Samples were assayed for coagulation factors (fibrinopeptide A, antithrombin III, protein C), fibrinolytic factors [tissue-type plasminogen activator (t-PA), alpha 2 antiplasmin, plasminogen activator inhibitor (PAI-1)] and markers of platelet activation (platelet factor 4, beta thromboglobulin). RESULTS: Of 46 patients who underwent successful PTCA, restenosis, defined as loss in absolute gain of more than 50%, occurred in 16 (35%). The minimal luminal diameter (mean +/- SD) at follow-up in those who had suffered restenosis was 1.07 +/- 0.7 mm compared with 1.73 +/- 0.5 mm in the non-restenotic patients. However, no significant differences in the levels of markers of platelet activation, coagulation factors, or fibrinolytic factors were observed between the two groups. The only significant difference between the groups was a higher platelet count in the restenotic patients [median (interquartile range): 263 (247-278) versus 224 (175-263), P < 0.05]. CONCLUSION: Our results suggest that patients who suffer restenosis following PTCA appear to have no clearly detectable pre-existing imbalance in their prothrombotic/antithrombotic status. Although the platelet count was higher in restenotic patients, the levels of markers of platelet activation were no different in the two groups. Thus, it is at present unlikely that simple blood assays before PTCA assessing an individual's 'thrombotic state' can help to predict which of the 30-40% of patients undergoing PTCA will suffer restenosis.

Angiographic restenosis after angioplasty: comparison of definitions and correlation with clinical outcome.

BACKGROUND: The aim of this study was to assess which of the currently used definitions of restenosis most closely indicates degree of recurrence and clinical status by 1) correlating percentage luminal renarrowing with restenosis defined according to each of four definitions, and 2) evaluating which definition was best predicted by clinical recurrence. METHODS: Quantitative angiography in 125 patients was undertaken either at time of early clinical presentation or at 6-month follow-up after percutaneous transluminal coronary angioplasty (PTCA). Absolute luminal diameters measured before and after PTCA and at follow-up were plotted as the percentage return from post-PTCA toward pre-PTCA value. All patients were also defined as restenosed or not restenosed according to each of the four definitions. RESULTS: The angiographic restenosis rate varied from 31% to 47%. Other than for "loss of 50% absolute gain," all definitions defined restenosis in some patients, despite the degree of return from post-PTCA to pre-PTCA value being less than 50%. Early recurrent symptoms predicted angiographic restenosis best, irrespective of angiographic definition, whereas history of recurrent angina or positive exercise testing alone at follow-up were poor predictors (range, 0.46 to 0.54). The predictive value increased (0.75 to 0.87) when exercise testing was positive in patients complaining of angina. The definition "loss of 2 standard deviations" gave the lowest values for positive or negative predictive values irrespective of clinical parameter. CONCLUSIONS: "Loss of 50% absolute gain" may be the best compromise definition. Patients admitted early with angina should undergo recatheterization, whereas exercise tests should be reserved for patients who complain of angina at routine follow-up.

Arrhythmogenic right ventricular dysplasia.

Right ventricular dysplasia is a primary disorder of the right ventricular myocardium characterised by a progressive replacement by adipose or fibrous tissue, proceeding from the epicardium towards the endocardium. Right ventricular dysplasia with the predominant clinical manifestation of an arrhythmia of right ventricular origin is defined as arrhythmogenic right ventricular dysplasia. There is, however, a wide spectrum of clinical presentation and physical findings owing to the polymorphism of the condition. The aetiology of right ventricular dysplasia remains unknown. Right ventricular angiography is currently regarded as the gold standard for the clinical diagnosis of right ventricular dysplasia Ventricular endomyocardial biopsy can be useful in confirming the diagnosis but a negative biopsy does not exclude the diagnosis of right ventricular dysplasia. There have been few electrophysiological studies and these, in general, have failed to help in risk stratification. Treatment is focused on the prevention of potentially lethal right ventricular electrical instability.

Failed thrombolysis in myocardial infarction.

Prompt treatment with thrombolytic therapy in acute myocardial infarction has been proven to reduce infarct size and mortality. However, reperfusion fails to occur in 30-50% of patients, either due to impaired epicardial artery flow or microvascular occlusion, with these patients experiencing a higher morbidity and mortality. We review the diagnosis and management of failed thrombolysis in acute myocardial infarction.

Prothrombin fragment F1 + 2 concentrations for monitoring anticoagulation therapy with heparin.

We have compared the activated partial thromboplastin time with measurement of prothrombin fragment F1 + 2 concentrations (ELISA assay) during a 24-h period in a group of patients (n = 10) who had undergone elective coronary angioplasty and were anticoagulated post-procedure with heparin 1000 U/h. Four hours after the procedure all the patients were adequately anticoagulated according to activated partial thromboplastin time (median ratio 4.7:1) and the prothrombin fragment F1 + 2 concentration was significantly lower than pre-angioplasty values (0.5 vs 1.4 nmol/l, p = 0.04). At 24 h the median activated partial thromboplastin time ratio was still higher than the pre-procedure value (1.35 vs 0.9, p < 0.01), but the prothrombin fragment F1 + 2 concentration had risen to 2.1 nmol/l, with more variability in individual results within the patient group for the prothrombin fragment F1 + 2 concentration than for activated partial thromboplastin time (interquartile ranges (Q1, Q3) prothrombin fragment F1 + 2, 1.2-2.5; activated partial thromboplastin time, 1.2-1.5). The activated partial thromboplastin time is the standard method of monitoring the anticoagulant effect of heparin but may not fully reflect the functional coagulation status and accurately identify individual patients with less than adequate anticoagulation. Prothrombin fragment F1 + 2 concentrations may provide a more reliable indicator in individual patients of functional coagulation status in certain important situations where anticoagulation is critical such as following complicated coronary angioplasty.

Monitoring anticoagulation following intracoronary procedures: which method?

We have assessed bedside kits for monitoring the activated partial thromboplastin time and the activated clotting time by comparing them with laboratory activated partial thromboplastin time values. To determine the accuracy of anticoagulation we have concurrently measured the plasma heparin concentrations, and plasma prothrombin fragment F1 + 2 concentrations. Serial samples were taken from patients undergoing elective percutaneous transluminal coronary angioplasty (n = 14). Readings were taken pre-procedure, 30 min after administration of a heparin bolus (10,000 U) and 1, 2 and 3 h after commencement of a constant heparin infusion (15 U/kg/h) postprocedure. Activated partial thromboplastin time results obtained with the bedside kit compared reliably with laboratory values (r = 0.8), were rapidly available and were reflected by appropriate changes in prothrombin fragment F1 + 2 and heparin concentrations. However, the relationship between activated partial thromboplastin time values and activated clotting time was less precise (r = 0.59). Therefore, for routine and frequent monitoring of anticoagulation with heparin, a bedside activated partial thromboplastin time kit provides adequate control of therapy but in instances were particularly tight control of anticoagulation is required, use of prothrombin fragment F1 + 2 concentrations may be more appropriate.

The effect of low dose nitroglycerin on plasma heparin concentrations and activated partial thromboplastin times.

We have investigated the effects of low dose nitroglycerin on the activated partial thromboplastin time (APTT), plasma heparin concentration, antithrombin III activity (AT-III) and platelet factor 4 (PF4) levels in a group of 42 patients receiving intravenous heparin and low dose nitroglycerin (GTN) following percutaneous transluminal coronary angioplasty (PTCA). Venous samples were taken before PTCA and at 2, 4 and 24 h after the start of the infusions. Despite the heparin infusion being constant, the median APTT ratio (interquartile range) was significantly lower at the 4 h sample time compared to the 2 h sample time (4.4 [3.8-4.5] vs 2.6 [1.8-4.0], P < 0.05). At this time there was also a significantly lower median plasma heparin concentration compared to the 2 h sample (0.35 [0.2-0.7] vs 0.17 [0.1-0.3] P < 0.05). There were no significant differences in AT-III activity or PF4 levels at 4 h compared to the 2 h sampling time. In another group of patients (n = 20) who received intravenous heparin alone following PTCA also at 1000 U/h there were no significant differences in median APTT ratios (4.4 [4.3-4.5] vs 4.2 [2.9-4.5]), or in median plasma heparin concentrations (0.26 [0.14-0.96] vs 0.22 [0.18-0.87]) at 4 h compared to 2 h. Our observations confirm that nitroglycerin can interfere with the anticoagulant effect of heparin even at low doses. Although the exact mechanism involved remains unknown, this study suggests it is likely to be a result of a reduction in plasma heparin levels, perhaps through acceleration of normal heparin elimination.

Lone atrial fibrillation and anticoagulant therapy.

Assessment of risk of thromboembolism and potential benefit of prophylaxis with long-term anticoagulant therapy in lone atrial fibrillation is hampered by a lack of consensus regarding definition of lone atrial fibrillation. In general, patients less than 60 years of age with normal left ventricular function and left atrial size have a low risk of thromboembolic events and are unlikely to gain any significant benefit with anticoagulants; however, patients older than 60 years with impaired left ventricular function, enlarged left atrium, and/or associated conditions such as hypertension have an increased risk of thromboembolism and would benefit from long-term anticoagulant therapy. Decisions regarding anticoagulant usage would be simplified by using a scoring system containing clinical and investigational variables.

Angioplasty balloon compliance: can in vivo size be predicted from in vitro pressure profile measurements?

BACKGROUND AND HYPOTHESIS: This study was undertaken to determine whether the behavior of angioplasty balloons within coronary arteries may differ from that anticipated from data provided by the manufacturers. In particular, the in vitro pressure-diameter profiles may not truly represent in vivo sizes. METHODS: Thus, we assessed the degree of correlation of in vitro with in vivo measurements obtained during routine angioplasty practice. In vivo size of 2.5 mm compliant (n = 8) and 3 mm semicompliant (n = 8) balloons was assessed using quantitative angiography for first, second, and third inflations. RESULTS: In vivo size was less than expected from in vitro measurements. In general balloon diameter increased with inflation pressures up to 8 atmospheres, and some degree of elastic recoil was evident with both balloon types after the last inflation. CONCLUSION: In vivo balloon size may not be accurately predicted from manufacturers' published data. Size is more likely to be affected by factors such as lesion characteristics and elasticity of the vessel wall than by balloon material compliance characteristics.