Genetic epidemiology of coronary artery disease: an Asian Indian perspective.

Coronary artery disease (CAD) has emerged as a major cause of morbidity and mortality worldwide. Recent findings on the role of genetic factors in the aetiopathology of CAD have implicated novel genes and variants in addition to those involved in lipid and lipoprotein metabolism. However, our present knowledge is limited due to lack of clarity on their exact identity and the quantum of impact on disease susceptibility, and incident risk. It is a matter of great interest to understand the role of genetic factors in ethnic populations that have a strong underlying predisposition to CAD such as the South Asian populations, particularly among Asian Indians living in India and abroad. Although, a number of isolated studies do implicate certain gene polymorphisms towards enhanced disease susceptibility, the available data remains scanty and inconclusive as they have not been validated in large, prospective cohorts. The present review aims to consolidate the available literature on the genetics of CAD in Asian Indians and seeks to provide insights on the concerns that need to be addressed in future studies to generate information having clinical value.

The role of T-helper cells in atherosclerosis.

Atherosclerosis is rapidly gaining recognition as an inflammatory disease showing contribution from innate and adaptive immunity pathways towards disease initiation and progression. Components of adaptive immunity especially T cells, are shown to be involved in atherogenesis and subsets of T cells are known to drive/ dampen inflammatory processes in atherosclerosis. However, the regulatory balance between the T cell subsets remains unclear. In this review, we summarize the role of T helper cells Th1, 2, 3 and 17, and regulatory cells Treg in atherosclerosis by studying the cytokines involved in Th cell functioning. We further examine the diverse roles of T helper cells for regulating the progression of atherosclerosis.

Extended prophylaxis with bemiparin for the prevention of venous thromboembolism after abdominal or pelvic surgery for cancer: the CANBESURE randomized study.

BACKGROUND: There is not enough clinical evidence to make a strong recommendation on the optimal duration of thromboprophylaxis using low-molecular weight heparins (LMWH) in patients undergoing major cancer surgery. PATIENTS AND METHODS: CANBESURE is a randomized, double-blind study which enrolled patients admitted for abdominal or pelvic surgery for cancer. They received 3500 IU of bemiparin subcutaneously once daily for 8 days and were then randomized to receive either bemiparin or placebo for 20 additional days. Bilateral venography was performed after 20 days and evaluated blinded. The primary efficacy outcome was the composite of deep vein thrombosis (DVT), non-fatal pulmonary embolism (PE) and all-cause mortality at the end of double-blind period. Major venous thromboembolism (proximal deep-vein thrombosis, non-fatal pulmonary embolism and venous thromboembolism-related deaths) was also evaluated. The primary safety outcome was major bleeding. RESULTS: Six hundred and twenty-five and 488 patients were included in the safety and main efficacy analyzes, respectively. The primary efficacy outcome occurred in 25 out of 248 patients (10.1%) in the bemiparin group and 32 out of 240 (13.3%) in the placebo group (relative risk reduction 24.4%; 95% CI: -23.7-53.8%; P = 0.26). At the end of double-blind period, major venous thromboembolism occurred in 2 (0.8%) and 11 (4.6%) patients, respectively (relative risk reduction 82.4%; 95% CI: 21.5-96.1%; P = 0.010). No significant difference was found in major bleedings. CONCLUSIONS: Four weeks compared with 1 week of prophylaxis with bemiparin after abdominal or pelvic cancer surgery did not significantly reduce the primary efficacy outcome, but decreased major venous thromboembolism (VTE) without increasing hemorrhagic complications.

The role of heat shock protein (HSP) in atherosclerosis: Pathophysiology and clinical opportunities.

The highly conserved heat-shock proteins (HSPs) from mammals and microbial reagents are among the immunogenic proteins. Their expression is induced in response to a wide variety of physiological and environmental insults. Their functions as molecular chaperones allow cells to adapt to gradual changes in their environment and to survive in otherwise lethal conditions. Although the role of HSPs in atherosclerosis remains controversial, HSPs were thought to act as autoantigens, and trigger both cell- and antibody-mediated immune responses. However, HSPs possess immunoregulatory attributes as well and therefore, are being exploited for immunomodulation of atherosclerosis either by the adaptive or innate immune system. This review will focus on a number of HSPs from different families including HSPE, HSPB, DNAJ, HSPD, HSPA, HSPC and HSPH. The role of these HSPs, their protective vs. immunogenic properties with special emphasis on their potential as targets to develop therapeutic agent against atherosclerosis will be discussed.

The role of integrin-mediated cell adhesion in atherosclerosis: pathophysiology and clinical opportunities.

Integrins have been reported to mediate cell survival, proliferation, differentiation, and migration programs. For this reason, the past few years have seen an increased interest in the implications of integrin receptors in atherosclerosis. This review considers the potential role of integrins in atherosclerosis and also addresses why integrins present attractive targets for drug design. It discusses the properties of the integrin-based chemotherapeutic agents currently under consideration clinically and endeavours to provide insights into development of cardiovascular drugs using integrins as targets.

Major joint replacement. A model for antithrombotic drug development: from proof-of-concept to clinical use.

AIM: Development of antithrombotic compounds has traditionally been performed in patients undergoing total hip and knee replacement surgery. A high number of asymptomatic deep-vein thromboses are radiologically detectable, and bleeding and other adverse events (AE) are easy to observe. However, standardization of study procedures and endpoints in early proof-of-concept studies and late pure clinical endpoint studies has been lacking. This has made comparison between studies difficult, economic analyses speculative and potential benefits of applying the drug regimen in non-selected patients uncertain. In this paper, the International Surgical Thrombosis Forum proposes a strategy for the clinical investigation of new pharmacological agents for the prophylaxis of postoperative thrombotic events. METHODS: First, dose titration safety studies of short duration, in highly selected patients using objective venographic endpoints are recommended. Bleeding should be divided into the quantified volume of surgical bleeding and other adjudicated clinical bleeding events. The number of AE should be described for each dose step and classified according to International Coding of Diagnoses (ICD). Second, a dose confirmatory study of moderate exposure period and sufficient follow-up time is recommended. The exclusion criteria should be restricted to contraindications of the compared drugs and technical procedure. RESULTS: The efficacy, bleeding and AE should be similar to those used in dose-titration studies. In addition, the failure rate of the drug to exert its effect and the net clinical benefit should be calculated. CONCLUSION: Finally, trials with simple clinical endpoints and long follow-up should be conducted to evaluate the potential benefits of the drug-regimen in non-selected populations.

Assessment of the variation in menopausal symptoms with age, education and working/non-working status in north-Indian sub population using menopause rating scale (MRS).

OBJECTIVE: To study the variation of the menopause rating scale (MRS) scores with age, working/non-working and educated/uneducated status in a cohort of north-Indian subpopulation and to look for the possible reasons for the incurred variations. MRS is a well-known and validated instrument for assessing the frequency and intensity of menopausal symptoms. METHOD: A menopause clinic was organized in collaboration with a primary care centre (under the guidance of a gynecologist). A random sample of 208 women aged 35-65 years participated in the study. The MRS scale, a self-administered standardized questionnaire was applied with additional patient related information (age at menopause, level of education, working/non-working and exercising or not). RESULTS: The results were evaluated for psychological (P), somatic (S), and urogenital (U) symptoms. The average age at which menopause set in, in the cohort was found to be 48.7+/-2.3 years (46.4-51 years). Based on the average age at the menopause, the cohort was divided into peri (35-45), menopausal/early menopause (46-51) and the postmenopausal (52-65) groups. A significantly higher % of perimenopausal women (36%) showed a P score of > or =7; while a higher % of postmenopausal showed S score and U score > or =7 (>40%; p< or =0.001). Working women seem to suffer more from psychological symptoms whereas non-working women showed a greater incidence of somatic symptoms. Educated women showed a lower incidence of psychological and somatic symptoms. CONCLUSIONS: Present study indicates that age, level of education and working/non-working status (in a group of women with same socio-cultural background) may also contribute to significant variations in menopausal symptoms.

Management of venous thromboembolism.

INTRODUCTION: Venous Thromboembolism is an important healthcare problem the world over, resulting in significant morbidity, mortality and resource expenditure. The rationale for use of thromboprophylaxis is based on solid principles and scientific evidence. Indian perspective on this topic is lacking due to the non-availability of published Indian data. This document reviews the available International and Indian data and discusses the relevance of recommendations for prevention and management of Venous Thromboembolism (VTE) in the Indian context. MATERIALS AND METHODS: Meetings of various specialists from different Indian hospitals in the field of Gastrointestinal Surgery, General and Vascular Surgery, Hematology, Intensive Care, Obstetrics and Gynecology, Oncology and Orthopedics were held in the months of August 2005 to January 2006. The guidelines published by American College of Chest Physicians (ACCP), the International Union of Angiology (IUA), and the Royal College of Obstetricians and Gynecologists (RCOG), were discussed during these meetings. The relevance of these guidelines and the practical implications of following these in a developing country like India were also discussed. Any published data from India was collected from data base searches and the results, along with personal experiences of the participating specialists were discussed. The experiences and impressions of the experts during these meetings have been included in this document. Data from recent sources (International Union of Angiology and the National Comprehensive Cancer Network (NCCN) Practice guidelines in Oncology on Venous thromboembolic disease) was subsequently also included in this document. RESULTS: The suggestions formulated in this document are practical, and would intend to serve as a useful practical reference. CONCLUSIONS: A number of unanswered questions remain in the field of thromboprophylaxis, and carefully designed research protocols may help answer some of these. Implementation of the suggestions outlined in the document remains to be studied in the Indian context.

Structure-activity relationship studies on ADAM protein-integrin interactions.

The ADAM (a disintegrin and metalloprotease) family of proteins possess multi-domain structures composed of a signal peptide, a prodomain, a metalloprotease domain, a disintegrin-like domain, a cysteine rich domain, an epidermal growth factor-like domain, a transmembrane domain and cytoplasmic tail. The disintegrin-like domain shares sequence similarity with the soluble venom disintegrins, a family of proteins which are potent inhibitors of integrin-mediated platelet aggregation and cell adhesion. Several ADAMs have been reported to interact with integrins, and the disintegrin-like domain may be crucial part in this respect. A description of structure-activity relationship of ADAM proteins interacting with integrin is outlined in this review. The review highlights recent reports on potential integrin family for ADAMs and how ADAMs selectively modulate interaction for integrin mediated cell function. Lastly, it describes progress in understanding the structural features and functional roles of the ADAMs in normal and pathological conditions and how this insight may assist the development of new therapeutic approaches.

Antithrombotic therapy in patients with chronic heart failure: rationale, clinical evidence and practical implications.

Chronic heart failure (CHF) is traditionally associated with increased risk of thromboembolic complications. Key features of CHF pathophysiology, such as impairment of intracardiac hemodynamics, peripheral blood flow deceleration, neuroendocrine activation, chronic oxidative stress and proinflammatory changes, could explain the predisposition to thromboembolism. However, conclusive epidemiologic data on thromboembolic event incidence in CHF are lacking. Furthermore, the place of antithrombotic therapy in CHF management is still uncertain. Apart from established indications for warfarin (e.g. atrial fibrillation and previous embolic events), there is no robust evidence to support administration of vitamin K antagonists to other patients with CHF, particularly to patients in sinus rhythm. The role of aspirin in preventing thromboembolism in these patients is also controversial. Large randomized trial data on the effectiveness and risks of warfarin and aspirin use in CHF patients with sinus rhythm are forthcoming. This article provides a brief overview of the epidemiologic and pathobiological background of thromboembolism in CHF, and discusses the up-to-date clinical evidence on antithrombotic therapy in detail.

Integrins in drug targeting-RGD templates in toxins.

Integrins are a family of heterodimeric receptors, which modulate many cellular processes including: growth, death (apoptosis), adhesion, migration, and invasion by activating several signaling pathways. Integrin-binding RGD (arginine-glycine-aspartic acid) is found in several important extracellular matrix proteins which serve as adhesive integrin ligands. The RGD motif has also been found in many toxins from snake venom and other sources that specifically inhibit integrin binding function and serve as potent integrin antagonists, particularly of platelet aggregation and integrin-mediated cell adhesion. Many of these proteins have potential as therapeutic agents which can target integrins directly. Structural and functional studies of several RGD-containing toxins suggest that the inhibitory potency of these proteins lies in subtle positional requirements of the tripeptide RGD at the tip of a flexible loop, a structural feature for binding to integrins. In addition, amino acid residues in this loop in close vicinity to the RGD-motif determine the integrin-binding specificity and selectivity. This review will present a review of integrin structure and function, and of disintegrin structural features responsible for their activity as antagonists of integrin function. The use of integrins in drug targeting and integrins as targets for drug delivery by using the RGD as a template structure will also be discussed.

Low molecular weight heparins in cardiovascular medicine.

Cardiovascular diseases are the major cause of morbidity and mortality in the Western countries and their prevalence is increasing in developing world. The final biological evolution of atherosclerotic process, supporting development and progression of cardiovascular diseases, is thrombosis. In the most recent years several clinical trails have established that low molecular weight heparins play a major role in the area of prevention and treatment of arterial and venous thrombosis. It is now established, that low molecular weight heparins are efficacious and safe anticoagulant options for patients with deep vein thrombosis, pulmonary embolism, unstable angina and non-ST-segment elevation myocardial infarction. In addition, low molecular weight heparins play a major role to prevent thromboembolic events in patients with chronic diseases (e.g. due to cerebrovascular ischemic events, cancer) and in patients undergoing surgical interventions. Clinical trials have also shown that low molecular weight heparins might play a role in the treatment of patients with ST-segment elevation acute myocardial infarction, in the prevention of thrombotic events in patients with congestive heart failure, and in patients undergoing percutaneous coronary interventions. The combined use of low molecular weight heparins with fibrinolysis and other antithrombotic agents has been also studies in a number of clinical trials. This review summarises the results of the most recent clinical studies regarding the use of low molecular weight heparins in prevention and treatment of cardiovascular diseases.

Snake venom metalloproteinase containing a disintegrin-like domain, its structure-activity relationships at interacting with integrins.

Snake venom disintegrins represent a family of RGD (Arg-Gly-Asp) or KGD (Lys-Gly-Asp)-containing proteins which have been reported to be unique and potentially useful tools not only for investigating integrin-ligand interactions, but also for the development of anti-thrombotic agents in terms of their anti-platelet activities. Snake venom proteins containing a disintegrin-like domain represent another super-family of proteins in which many of them have been demonstrated to have similar ability to inhibit platelet aggregation and integrin-mediated cell adhesion as the disintegrins. This super-family includes a large number of snake venom metalloproteinases and disintegrin related, RGD-containing snake venom proteins (disintegrin-like proteins) such as dendroaspin. Recently, a family of homologues of the snake venom metalloproteinases have been found in a wide variety of mammalian tissues as well as in other eukaryotic organisms termed ADAM (a disintegrin-like and metalloproteinase) proteins. ADAMs are members of the metazincins that also include the related matrix metalloprotease (MMPs). Some of ADAM proteins have now shown to interact with integrins, and the disintegrin-like domain may be crucial part in their function as proteases. A description of structure-activity relationships of snake venom proteins containing a disintegrin-like domain is outlined in this review, along with reports of the modulation of protein activity by recombinant mutation. Comparison is also made of the structural and functional features of the metalloproteinases in snakes compared with those from other species. The review is intended to provide insights in which may assist the development of new therapeutic approaches.

Chronic heart failure- potential for pharmacological intervention.

Heart failure is commonly associated with vascular diseases and a high rate of athero-thrombotic events, but the risks and benefits of antithrombotic therapy are unknown. The incidence of thromboembolism in heart failure patients (which may include stroke, peripheral embolism, pulmonary embolism) seems to be around 2%, based on the data available from several small studies. However, the incidence of thromboembolism should greatly depend upon what is being looked at in each of these studies, as it will (generally) not be individually categorised. There is very little true epidemiological data to base this figure. The pathophysiology of heart failure is complex. There are many well- recognised factors, which are associated with thrombosis in heart failure patients, such as vascular abnormalities, increased coagulability and impaired blood flow. In the past 50 years, many studies have been performed to find out if oral anticoagulation is of benefit for the prevention of thromboembolism in patients with heart failure. Expert therapeutic guidelines in the Europe and North America agree that there is insufficient evidence to recommend that antithrombotic therapy should be given to patients with heart failure, unless they have atrial fibrillation or, perhaps, a previous thrombo-embolic episode. There is a lack of evidence for any antithrombotic agent that is effective in patients with heart failure; therefore, randomised clinical trials need to be designed to test the hypothesis that patients with chronic heart failure would have benefit from anticoagulant therapy. This review summarises the incidence, potential mechanism and therapeutic approaches for the management of thromboembolism in heart failure.

Modulation of integrin-binding selectivity by mutation within the RGD-loop of snake venom proteins: a novel drug development approach.

Integrins are a family of heterodimeric class I transmembrane receptors, many of which bind to the RGD sequence in adhesive proteins and mediate the adhesive interactions of a variety of cells. The RGD motif has also been found in snake venom proteins that specifically inhibit integrin binding function and serve as potent integrin antagonists. The majority of these proteins interact with beta1 and beta3 associated integrins and their potency is at least 500-2000 times higher than short RGD peptides. Structural and functional studies suggest that the inhibitory potency of these proteins lies in subtle positional requirements of the tripeptide RGD that is harboured in a defined flexible loop. The integrin-binding specificity and selectivity of each of the proteins is controlled by amino acid residues in this loop in close vicinity to the RGD-motif. The review includes an overview of the structure and function of snake-venom integrin antagonists. The ability of these proteins to control platelet aggregation, cell adhesion and ligand binding is compared to that of short linear, cyclic RGD-peptides and RGD-containing proteins and the influence of modulation of amino acid residues flanking the RGD motif is also considered. The review is intended to provide insight into the development of novel inhibitors as drugs.

Inhibition of human alpha-thrombin by a phosphonate tripeptide proceeds via a metastable pentacoordinated phosphorus intermediate.

X-ray crystallographic studies of human alpha-thrombin with a novel synthetic inhibitor, an acyl (alpha-aminoalkyl)phosphonate, reveal the existence of a pentacovalent phosphorus intermediate state. Crystal structures of the complex of alpha-thrombin with the phosphonate compound were determined independently using crystals of different ages. The first structure, solved from a crystal less than seven days old, showed a pentacoordinated phosphorus moiety. The second structure, determined from a crystal that was 12 weeks old, showed a tetracoordinated phosphorus moiety. In the first structure, a water molecule, made nucleophilic by coordination to His57 of alpha-thrombin, is bonded to the pentacoordinated phosphorus atom. Its position is approximately equivalent to that occupied by the water molecule responsible for hydrolytic deacylation during normal hydrolysis. The pentacoordinated phosphorus adduct collapses to give the expected pseudo tetrahedral complex, where the phosphorus atom is covalently bonded to Ser195 O(gamma). The crystallographic data presented here therefore suggest that the covalent bond formed between the inhibitor's phosphorus atom and O(gamma) of Ser195 proceeds via an addition-elimination mechanism, which involves the formation of a pentacoordinate intermediate.

Arg-Tyr-Asp (RYD) and Arg-Cys-Asp (RCD) motifs in dendroaspin promote selective inhibition of beta1 and beta3 integrins.

Arg-Gly-Asp (RGD) is a unique minimal integrin-binding sequence that is found within several glycoprotein ligands. This sequence has also been found in snake-venom anti-platelet proteins, including the disintegrins and dendroaspin, a natural variant of short-chain neurotoxins isolated from the venom of Dendroaspis jamesonii. In the present study, the motifs RYD and RCD were introduced into the dendroaspin scaffold to replace RGD. Both motifs in dendroaspin caused inhibition of ADP-induced platelet aggregation with IC(50) values of 200 and 300 nM respectively, similar to that of the wild-type RGD motif (170 nM). In comparison with wild-type dendroaspin, both RYD- and RCD-containing dendroaspins were more selective in the inhibition of the adhesion of K562 cells to laminin rather than to fibrinogen and fibronectin, even though they were 10-30-fold less potent at inhibiting K562 cell (containing alpha(5)beta(1) integrin) adhesion to laminin compared with wild-type. Interestingly, the RYD motif produced a similar IC(50) value to the RGD motif at inhibiting A375-SM cell (beta(3) integrin) adhesion to collagen, whereas the RCD motif was approx. 2-6-fold less potent compared with either RGD or RYD. These findings show that the selectivity of dendroaspin binding to beta(1) and beta(3) integrins can be modulated by the introduction of alternative cell recognition sequences.

Evaluation of the role of proline residues flanking the RGD motif of dendroaspin, an inhibitior of platelet aggregation and cell adhesion.

The effect of a panel of proline mutants of dendroaspin, an inhibitor of platelet aggregation and cell adhesion, including A(42)-dendroaspin, A(47)-dendroaspin, A(49)-dendroaspin, A(42,47)-dendroaspin and A(47,49)-dendroaspin, was investigated using platelet-aggregation and cell-adhesion assays. Here we show that a single alanine-for-proline substitution did not affect potency when measured as the ability either to inhibit platelet aggregation induced by ADP (IC(50) approximately 170 nM) or to block transfected A375-SM cell adhesion to fibrinogen in the presence of Mn(2+) as compared with wild-type dendroaspin. By comparison, double proline substitution with alanines significantly reduced the potency in both assays by approx. 5-8-fold. These observations, therefore, suggest that proline residues flanking the RGD motif in dendroaspin and other RGD-containing venom proteins, e.g. disintegrins, may contribute to maintaining a favourable conformation for the solvent-exposed RGD site for its recognition by integrin receptors.