Anticoagulant and antiplatelet agents: their clinical and device application(s) together with usages to engineer surfaces

An essential aspect of the treatment of patients with cardiovascular disease is the use of anticoagulant and antiplatelet agents for the prevention of further ischaemic events and vascular death resulting from thrombosis. Aspirin and heparin have been the standard therapy for the management of such conditions to date. Recently, numerous more potent platelet inhibitors together with anticoagulant agents have been developed and tested in randomized clinical trials. This article reviews the current state of the art of antiplatelet and anticoagulant therapy in light of its potential clinical efficacy. It then focuses on the usages of these agents in order to improve the performance of clinical devices such as balloon catheters, coronary stents, and femoropopliteal bypass grafting and extra corporeal circuits for cardiopulmonary bypass. The article then goes on to look at the usage of these agents more specifically heparin, heparan, hirudin, and coumarin in the development of more biocompatible scaffolds for tissue engineering.     

Synthesis and structure-activity relationship of new analogues of antistasin.

Intensive investigation connected with the development of new anticoagulant agents for the treatment of cardiovascular diseases was carried out. Direct and specific inhibition of thrombin and Factor Xa-like serine proteases in the coagulation cascade has been the focus of many efforts to design novel anticoagulants over the past decade. This work reports the synthesis and biological activity of new anticoagulant peptide analogues of natural isoforms 2 and 3 of antistasin. In addition they include different tripeptide sequences in their molecules, which are highly active inhibitors of different serine proteases such as plasmin, trypsin, thrombin and Factor Xa.     

ANTICOAGULANT DRUG TREATMENT OF CORONARY ARTERY DISEASE

Anticoagulant therapy of arteriosclerotic heart disease may prove to be most valuable when applied on a long-term basis for prevention of recurrent myocardial infarction. While its prophylactic value in impending infarction has not been established, at least the accepted treatment for the acute stage is already begun if an anticoagulant has been administered before an inevitable infarction occurs.The chief value of the anticoagulant, though, seems to lie in preventing cardiac mural thrombosis and extracardiac thromboembolism. It is by this effect, apparently, that mortality has been reduced by 50 per cent among survivors of myocardial infarction who receive continuous dicoumarin therapy.While the danger of hemorrhage is still present, it is being steadily reduced by increasing skill in the management of anticoagulant therapy, and for a long time the risk has been far outweighed by the reduction in coronary occlusion.Physicians have a duty to learn the use of anticoagulant therapy, obtain the facilities necessary for it, and apply it to patients who are able and willing to cooperate in prolonging their useful lives.     

Hemorrhage During Long-Term Anticoagulant Drug Therapy—Part IV: Selection and Management of Patients

Most serious hemorrhages that occur during long-term anticoagulant drug therapy are due either to poor patient selection or to poor management of the patient, or both.In each patient being considered for treatment, the risk of bleeding must be evaluated and classified as high, moderate or low.The clinician must especially assess the risk of intracranial hemorrhage in hypertensive patients, and must screen all patients for potential sources of gastrointestinal bleeding. There is ample time for such investigations, since initiating long-term anticoagulant therapy is not an emergency procedure.The desired level of prothrombin activity must be adjusted to the risks determined for each individual patient. There is no single “therapeutic range” applicable to all patients with their varying hemorrhagenic risks.Proper management includes sufficient laboratory testing to maintain the desired prothrombin level, and continued vigilance to detect signs of early bleeding.Preventable hemorrhage cannot be cited as evidence against the value of anticoagulant drug therapy.     

Long-term Anticoagulant Therapy after Myocardial Infarction in Women

A multicentre trial from five medical departments in Oslo has been carried out to determine the value in women patients of one year''s long-term anticoagulant therapy. Follow-up long-term laboratory control and anticoagulant dosage were performed at one centre (the Rikshospitalet). One hundred and fifty-nine patients were assigned randomly into two similar well-matched groups (control and treatment). Dosage was controlled by Thrombotest, aiming at 10–20% levels, and 50% of the tests were less than 14%. Compared with the control group, the treatment group showed a significant reduction in mortality and in reinfarction rate. No serious bleeding complications occurred. It is concluded that women benefit as much as men from long-term anticoagulant therapy.     

Target Specific Anticoagulant Peptides: A Review

Anticoagulant drugs are of crucial importance for the treatment and prophylaxis of thrombotic disorders. The use of traditional anticoagulants like heparin and warfarin is majorly associated with bleeding complications. In the quest for safer anticoagulation therapy, the interest for the isolation of novel anticoagulant compounds has shifted towards natural sources. Peptides can be considered as better alternative due to their therapeutic potential in the treatment of diseases. Peptides from hematophagous (blood-feeding) and venomous organisms have been recognized as potential anticoagulant agents. Of late, peptides derived from the hydrolysis of food proteins, including edible seaweeds, milk and seed proteins, have also shown to possess promising in vitro anticoagulant activity. To overcome the problems associated with regular anticoagulants, peptides targeting vital steps in the clotting cascade have been studied. This review focuses on anticoagulant peptides with known targets, inhibiting crucial factors in the coagulation cascade such as FXa, FXIa, FXIIa and FVIIa/TF complex, as well as peptides with unknown targets.     

Influencing the fibrinolytic activity by antithrombotics in patients with atherosclerosis

In 106 atherosclerotic patients receiving an anticoagulant therapy and 91 patients receiving acetylsalicylic acid, fibrinogen and fibrin degradation products were determined as well as euglobulin lysis before and after venous occlusion. Platelet function data and thromboxane (TXB2) were also determined. Since "moderate" anticoagulant therapy with thromboplastin time values 26-40% results in deteriorated fibrinolysis data, anticoagulant therapy is strictly to remain within the therapeutic range of 15-20% up to 25% thromboplastin time at maximum. Treatment with acetylsalicylic acid proved useful on condition that the required dose was determined individually. This type of treatment will then be able to reduce the thromboxane level and positively influence the fibrinolytic potential.     

Management of Transient Cerebral Ischemic Attacks

Transient ischemic attacks (TIAs) are brief reversible episodes of neurological dysfunction due to temporary focal cerebral ischemia. Angiography should be performed only when operation is indicated or when the diagnosis is in doubt. Surgical treatment is recommended when the patient is a good surgical risk, when the stenosis is more than 70 per cent in the appropriate vessel and in certain patients with less severe stenotic lesions that appear to be a probable source of emboli. Anticoagulant therapy is indicated when there are recurrent TIAs, when the patient is not a good surgical candidate and when no appropriate surgically remediable lesion is found by angiography. If there is any significant contraindication to anticoagulants they should not be given. Discontinuance of anticoagulant therapy when the patient has been symptom-free for six months is recommended. In the experience of the authors the TIA syndrome is more benign in its course than was originally suspected and a conservative approach to surgical and anticoagulant therapy is recommended.     

Hemorrhage During Long-Term Anticoagulant Drug Therapy—Part II: Gastrointestinal Hemorrhage

Most of the gastrointestinal hemorrhages occurring during long-term anticoagulant drug therapy of 2,013 patients (reported in the literature) were caused by underlying lesions (44 to 77). Of the 44 lesions, only seven were diagnosed before treatment was started.Most of the episodes of hemorrhage occurred with the prothrombin activity at a so-called “safe” level. Closer investigation before the anticoagulant therapy was begun might have brought the underlying lesion to light.     

An Investigation of the Hemorrhagic Diathesis in Patients Receiving Coumarin and Indanedione Anticoagulants

Coagulation studies were carried out on 10 patients who bled during anticoagulant therapy, in whom no other underlying cause for bleeding could be demonstrated, and 10 patients with similar degrees of hypoprothrombinemia who were not bleeding. The average age and sex distribution of the two groups was similar, and no association was noted between the occurrence of hemorrhage and the type of anticoagulant used, the duration of treatment or the nature of the underlying disease. Comparison of the results revealed no differences in the levels of factors II, VII, IX and X or in the glass and silicone (Siliclad) clotting time, the thromboplastin generation test and Thrombotest. It was concluded that all patients on anticoagulant drugs whose prothrombin time is in the therapeutic range or longer are potential bleeders and that one cannot necessarily predict those who will bleed on the basis of coagulation studies.     

Neurosurgical complications of anticoagulant therapy

Ten cases of subdural hematoma and one case of spinal epidural hematoma encountered in patients who were receiving anticoagulant therapy are discussed.This surprisingly large number of complications was observed within three years in a single hospital and represents 36.6% of all chronic and subacute subdural hematomas seen during the same period. The cases are analyzed and the conclusion reached that the causal relationship between anticoagulant therapy and hemorrhage cannot be denied.Suggestions are made as to how to decrease the danger of such complications.     

Long-term anticoagulation. Indications and management.

Each year half a million persons in the United States receive long-term anticoagulant therapy to prevent venous and arterial thromboembolism. Unfortunately, the relative benefits and risks of anticoagulant therapy have not been adequately quantified for many thromboembolic disorders, and the decisions as to whether, for how long, and how intensely to administer anticoagulation are often complex and controversial. Several expert panels have published recommendations for anticoagulant therapy for different thromboembolic disorders; the primary area of disagreement among these panels concerns the optimal intensity of anticoagulation. Recent research and analytic reviews have helped to clarify both the risk factors for and the appropriate diagnostic evaluation of anticoagulant-induced hemorrhage. Clinicians must be aware of the nonhemorrhagic complications of anticoagulant therapy, particularly during pregnancy. The administration of anticoagulants is difficult both in relation to dosing and long-term monitoring. Knowledge of the pharmacology of the anticoagulants, an organized approach to ongoing monitoring, and thorough patient education may facilitate the safe and effective use of these drugs.     

Stem Cell Therapy: A New Therapeutic Option for Cardiovascular Diseases

Cardiovascular diseases are known as one of major causes of morbidity and mortality worldwide. Despite the many advancement in therapies are associated with cardiovascular diseases, it seems that finding of new therapeutic option is necessary. Cell therapy is one of attractive therapeutic platforms for treatment of a variety of diseases such as cardiovascular diseases. Among of various types of cell therapy, stem cell therapy has been emerged as an effective therapeutic approach in this area. Stem cells divided into multipotent stem cells and pluripotent stem cells. A large number studies indicated that utilization of each of them are associated with a variety of advantages and disadvantages. Multiple lines evidence indicated that stem cell therapy could be used as suitable therapeutic approach for treatment of cardiovascular diseases. Many clinical trials have been performed for assessing efficiency of stem cell therapies in human. However, stem cell therapy are associated with some challenges, but, it seems resolving of them could contribute to using of them as effective therapeutic approach for patients who suffering from cardiovascular diseases. In the current review, we summarized current therapeutic strategies based on stem cells for cardiovascular diseases. J. Cell. Biochem. 119: 95–104, 2018. © 2017 Wiley Periodicals, Inc.     

Antitumor and anticoagulant activities of collagen protein from the holothurian <Emphasis Type="Italic">Apostichopus japonicas</Emphasis> modified by proteolytic enzymes

A collagen preparation with antitumor and anticoagulant activity was obtained from the body of the holothurian (sea cucumber) Apostichopus japonicus treated with a complex of proteolytic enzymes. Administration of the collagen preparation inhibited in vivo growth of Ehrlich solid adenocarcinoma 2-fold (P < 0.05) and contributed to the survival of ascitic tumor-bearing mice, increasing their life span by 29.4 ± 3.2% (P < 0.05). With its moderate anticoagulant activity, this preparation is a preferential inhibitor of the initial link of the blood coagulation system. The biomedical properties and the character of the chemical structure of the collagen protein obtained from A. japonicus suggest that the mechanism of its action is similar to that of the collagen-like protein endostatin and sulfated polysaccharides. The obtained protein may be applied as a nontoxic agent of supplementary therapy for oncological and cardiovascular diseases.     

Role of estrogen receptor-alpha in pharmacogenetics of estrogen action

PURPOSE OF REVIEW: To summarize recent data regarding the role of estrogen receptor-alpha polymorphisms in determining the response to estrogen therapy or the risk of clinical cardiovascular events. RECENT FINDINGS: Recent clinical trials of hormone replacement therapy for cardiovascular disease have yielded surprisingly negative results, shifting clinical opinions from a position of presumed cardiovascular benefit to one of confirmed harm. Understanding why hormone replacement therapy has beneficial effects on intermediate risk markers for cardiovascular disease, but produces an increase in cardiovascular events, is an important public health question with the potential to elucidate fundamentally important aspects on atherogenesis, cardiovascular disease, and the biology of estrogen action. One question concerning the cardiovascular effects of hormone replacement therapy is whether genetic factors can substantially modify individual responses to estrogen treatment. New clinical trial evidence is emerging that links the presence of particular variants in the estrogen receptor to the response of HDL and other intermediate endpoints to hormone replacement therapy. SUMMARY: One or more common variants in estrogen receptor-alpha are associated with a differential response to hormone replacement therapy in several domains of estrogen action. However, the effect of these variants on the risk of clinical cardiovascular events in the setting of hormone replacement therapy is not yet known. Additional research focusing on the clinical impact of common variants in estrogen receptor-alpha, estrogen receptor-beta and the progesterone receptor promise to improve clinical decision-making concerning the use of hormone replacement therapy and other novel estrogen agonists.     

The anticoagulant effect of prolame, N-(3-hydroxy-1,3,5(10)estratrien-17 beta-yl)-3-hydroxypropylamine, a novel amino-estrogen

The anticoagulant and estrogenic effects of prolame, N-(3-hydroxy-1,3,5(10)-estratrien-17 beta-yl)-3-hydroxypropylamine, are described. A single subcutaneous injection of prolame in male mice, ovariectomized mice, adult and infant male rats, produced dose-dependent increases of blood clotting time, which could be observed with the larger doses even after 4 days. In ovariectomized mice, prolame produced vaginal cornifications of shorter duration than those produced by estradiol-17 beta. The evidence suggests that, in contrast with currently used estrogens, prolame would not generate cardiovascular accidents if used for the treatment of prostatic carcinoma; it could also be exceptionally effective for the prevention of thrombosis.     

Observations on Anticoagulant Therapy in Thromboembolic Disease of the Brain

According to a recently reported study, anticoagulant therapy appears to be ineffective in thrombotic cerebrovascular disease when viewed from the standpoint of mortality, although it does control thrombosis in animals, recurrent ischemic attacks and progression of infarction in patients with stuttering strokes. The efficacy of anticoagulant therapy in preventing a catastrophic stroke is analyzed in the present report. Of 92 untreated patients followed up for an average period of 36 months, 28 suffered a recurrent stroke, only two of these being trivial. One trivial and 12 catastrophic strokes occurred in the first 16 months. Of 103 patients treated with anticoagulants for an average period of 16 months, seven had recurrent strokes, but five of these were trivial. In the first 16 months one catastrophic and four trivial strokes occurred. Anticoagulant therapy appears to be useful in preventing catastrophic strokes in selected patients in whom the risk of recurrent strokes justifies the risks involved in this treatment.     

Risks of discontinuing anticoagulant therapy in a selected group of patients with atherosclerotic heart disease: a prospective study

In 134 patients with coronary artery disease, long-term oral anticoagulant therapy (mean duration, 56 months) for acute myocardial infarction (98 patients), acute coronary insufficiency (25 patients) or severe chronic angina (11 patients) was terminated abruptly in 50 patients (group 1) and gradually in 84 (group 2). The 134 patients represented a homogeneous population of patients with coronary artery disease since most patients older than 75 years and those with conditions known to increase the risks of thromboembolic complications were excluded. The two groups were comparable in terms of sex, age, presence of risk factors, duration of anticoagulant therapy, and presence of angina and abnormal resting electrocardiograms during therapy. Patients were evaluated 6 months after cessation of anticoagulant therapy and, since abrupt withdrawal of therapy did not carry a higher risk than gradual discontinuation, data for groups 1 and 2 were tabulated together.Of the 84 patients with angina at the end of therapy 15 experienced an increase in its severity and this symptom appeared in another patient (relapse rate, 18%). Angina progressed to fatal acute myocardial infarction in four (mortality, 3%) and nonfatal infarction in two; however, all six had extensive coronary artery disease and poor left ventricular function. The results of this study suggest that neither abrupt nor gradual cessation of anticoagulant therapy is associated with an inordinate exacerbation of heart disease.     

Gene transfer to the vasculature: historical perspective and implication for future research objectives

Cardiovascular diseases are a major cause of fatality, disability, and economic burden in Western civilization. Although the pharmaceutical industry has delivered a plethora of drugs for treatment of diverse cardiovascular complaints, there remain many conditions for which pharmacological regimens are either nonexistent or largely ineffective. In contrast, remarkable progress has been made in the field of vascular gene transfer in the last decade. The vast majority of studies are preclinical, although a number of high profile vascular gene therapy clinical trials are in progress. In principle, vascular gene therapy represents an unprecedented opportunity to treat a host of cardiovascular diseases in humans although many scientific, clinical, and ethical obstacles remain. Here we discuss the rapid progress in preclinical vascular gene therapy, highlight the most appropriate gene delivery vectors, and discuss the advances toward the ultimate goal of an efficient and safe gene therapy for diverse cardiovascular diseases.     

Anticoagulant Therapy in Coronary Artery Disease: A Therapeutic Enigma

The authors'' experience with anticoagulant therapy in both the acute phase and the long-term management of myocardial infarction has proved disappointing. A review of the literature has failed to establish benefit when all patients with coronary artery disease are treated with anticoagulant drugs. A need for well-controlled studies still exists.