Characterization of glycosaminoglycans by 15N NMR spectroscopy and in vivo isotopic labeling

Characterization of glycosaminoglycans (GAGs), including chondroitin sulfate (CS), dermatan sulfate (DS), and heparan sulfate (HS), is important in developing an understanding of cellular function and in assuring quality of preparations destined for biomedical applications. While use of (1)H and (13)C NMR spectroscopy has become common in characterization of these materials, spectra are complex and difficult to interpret when a more heterogeneous GAG type or a mixture of several types is present. Herein a method based on (1)H-(15)N two-dimensional NMR experiments is described. The (15)N- and (1)H-chemical shifts of amide signals from (15)N-containing acetylgalactosamines in CSs are shown to be quite sensitive to the sites of sulfation (4-, 6-, or 4,6-) and easily distinguishable from those of DS. The amide signals from residual (15)N-containing acetylglucosamines in HS are shown to be diagnostic of the presence of these GAG components as well. Most data were collected at natural abundance of (15)N despite its low percentage. However enrichment of the (15)N-content in GAGs using metabolic incorporation from (15)N-glutamine added to cell culture media is also demonstrated and used to distinguish metabolic states in different cell types.

Thromboprophylaxis and thrombosis in medical, surgical, trauma, and obstetric/gynecologic patients

The International Consensus and the ACCP Sixth Consensus had a great impact on the clinical acceptance of LMWHs. These recommendations have been instrumental in initiating further clinical trial to answer key questions regarding thromboprophylaxis and in setting a new standard for patient care. Also, the key to cost containment in management of DVT/PE is to (1) define the etiology (blood coagulation protein or platelet defect), institute appropriate long-term therapy as indicated, and assess appropriate family members as indicated if a hereditary defect is found and (2) use LMWH as inpatient management. saving a minimum of 210,000.00 dollars per 1000 patients simply from cost savings of recurrence, saving 17 lives per 1000 patients, and saving exorbitant costs of care for patients with recurrence and development of chronic venous insufficiency. The use of outpatient LMWH will save 4,900,000.00 dollars per 1000 patients if applied to the 70% of patients with DVT who fit the criteria of no comorbid condition requiring hospitalization and who arrive early enough to allow a diagnosis to be sent home or hospitalized for 24 hours or less. The simple defining of defects leading to unexplained thrombosis will add another 3,000,000.00 dollars in savings per 1000 patients with DVT and approximately 350,000.00 dollars per 100 patients with thrombotic stroke. In those with transient ischemic attacks, defining the defect and instituting appropriate antithrombotic therapy, thereby potentially saving approximately 30% from developing a thrombotic stroke, amounts to approximately 350,500.00 dollars (= 30% of 1,168,500.00 dollars) in savings per 100 patients.

Proficient and cost-effective approaches for the prevention and treatment of venous thrombosis and thromboembolism

Thrombosis is clearly a common cause of death in the US. It is obviously of major importance to define the aetiology of deep vein thrombosis (DVT) as (i) many of these events are preventable if appropriate therapy, dependent upon the risk factors known is utilised; (ii) appropriate antithrombotic therapy will decrease risks of recurrence; (iii) the type of defect(s) and risk(s) will determine length of time the patient should remain on therapy for secondary prevention and (iv) if the defect is hereditary appropriate family members can be assessed. Aside from mortality, significant additional morbidity occurs from DVT including, but not limited to, stasis ulcers and other sequelae of post-phlebitic syndrome. Numerous studies have provided evidence that medical patients and patients undergoing surgery or trauma are at significant risk for developing DVT, including pulmonary embolism (PE). Thus, an important task for the clinician is to prevent DVT and its complications. It is important to define risk groups where prophylaxis must be considered. The attitudes and beliefs towards prophylaxis show great regional variations. This is true for the definition of risk groups, the proportion of patients receiving prophylaxis and prophylactic modalities used. For this reason, various 'consensus conference' groups have attempted to alleviate these problems; the primary mission of consensus guidelines is to provide optimal direction to the clinician in the setting of clinical practice. If the practice guidelines generated are successful they will assist clinicians in decision-making for their patients, and they will also provide protection against unjustified malpractice actions. Therapy may be complex, as clinical studies continue to identify more effective treatments. This review includes currently accepted approaches to the treatment of DVT. The clinical course of DVT is highly dynamic. When the response to therapy is not as expected, more than one cause of DVT may be present in a patient. Treatment must address the primary coagulopathy as well as any precipitating factors. The risk of pharmacological intervention must be balanced against potential benefit. If the incidence of DVT in a given disorder is low and if the mortality rate is similarly low, therapy with an agent known to be associated with a high risk for complications, such as warfarin, would not be indicated. If DVT is seen primarily after surgery or in other high-risk situations, therapy might be limited to a fixed time period. However, if the ongoing risk of DVT remains high or if a history of recurrent DVT dictates, lifelong therapy might be indicated. The recommendations presented are based upon published controlled trials; however, indications for therapy and therapeutic agents of choice will continually evolve. By applying the principles outlined in this review, substantial cost savings, reduction in morbidity and reductions in mortality should occur.

Cardiovascular chemotherapy: anticoagulants

Anticoagulant therapy has changed dramatically during the past two years. Low molecular weight heparin has substantially replaced unfractionated heparin as the parenteral anticoagulant of choice. The use of warfarin has substantially increased, especially for prevention of stroke in the setting of atrial fibrillation. It has become clear that warfarin cannot be administered effectively in an unmonitored fixed-dose fashion. The parenteral direct thrombin inhibitor desirudin was shown to be efficacious in the prevention of deep vein thrombosis in man. Small thrombin and factor Xa inhibitors with in vivo oral anticoagulant activity have been identified.

International consensus recommendations. Summary statement and additional suggested guidelines. European Consensus Conference, November 1991. American College of Chest Physicians consensus statement of 1995. International Consensus Statement, 1997

Since the NIH Consensus Conference in 1986, the developments in the field of prevention and treatment of venous thromboembolism were mainly characterized by a more specific and extended use of new prophylactic agents such as low-molecular-weight heparins as well as the perception that out-patients may be at risk for thromboembolic complications, too. Therefore, in 1991 and 1995, consensus conferences were held in Europe and North America in order to analyze the risk constellation of various patient populations and to give recommendations for primary prophylaxis and treatment of thromboembolic complications. The most recent, the 1997 International Consensus Recommendations are also discussed.