Search

Quinine is widely used for the common symptom of leg cramps. Quinine tablets require a prescription, but quinine and the product from which it is derived, cinchona, are also available without prescription. They are components of over-the-counter remedies for many common symptoms, of nutrition products, and of beverages such as tonic water and bitter lemon. Although quinine has been used for centuries, initially as an extract from the bark of the cinchona tree, allergic reactions to quinine can be severe and can affect multiple organs. These allergic reactions can cause thrombocytopenia, neutropenia, anemia, disseminated intravascular coagulation, acute renal failure, liver toxicity, and neurological abnormalities. Because quinine use is often intermittent, defining quinine as a cause of an acute disorder may be difficult. Moreover, since quinine use is often self-regulated, patients may not mention it in response to direct questions about medication use, adding to diagnostic difficulty. The diversity and severity of quinine-associated disorders and the difficulties of diagnosis are illustrated by the presentation of 4 case histories. Awareness of the variety of potential quinine-associated reactions is important for accurate diagnosis and critical for prevention of recurrent illness.

A support group for patients who have recovered from thrombotic thrombocytopenic purpura-hemolytic uremic syndrome (TTP-HUS), named The Oklahoma TTP-HUS Study Group, has been a successful program for 6 years. This group has met 3 times each year with an average attendance of 16 former patients; in addition, an average of 14 family members and friends have attended each meeting. Eighty-four percent of patients who attended a meeting were women as compared to 68% women among those who did not attend (P = 0.016). Twenty-three percent of patients who attended a meeting have relapsed as compared to 8% among those who did not attend (P = 0.006). There was also a difference in the rates of attendance among the different clinical categories of patients (P < 0.001). A survey of former patients, as well as their families and friends, documented that interest in learning more about TTP-HUS and talking with other people who have had TTP-HUS were principal motivations for attending the meetings. The meetings of The Oklahoma TTP-HUS Study Group have been successful not only for support of former patients but also for research. Long-term patient follow-up has been facilitated and the group discussions have revealed previously unreported persistent problems with cognitive ability and endurance. A survey of member centers of the American Association of Blood Banks and America's Blood Centers revealed no similar programs for patients who have recovered from TTP-HUS. The absence of a support group for TTP-HUS in the national survey contrasts to the 274 patient support groups and related wellness/education classes, including some for rare disorders, currently active in the Oklahoma City metropolitan area. The experience of The Oklahoma TTP-HUS Study Group suggests that it serves a previously unmet need., (Copyright 2003 Wiley-Liss, Inc.)

Estimates on the incidence of drug-induced thrombocytopenia range 5-40% in patients receiving heparin to < 1% with other causative agents. Systematically assessing drug-induced thrombocytopenia through a series of steps, each step providing additional evidence that the suspected agent is the true cause of thrombocytopenia, is the best way to identify the causative agent. Databases exist to aid in identification of the causative agent. Knowing which medications may be causative agents as well as which are not known to cause drug-induced thrombocytopenia, the aetiologies of drug-induced thrombocytopenia, signs and symptoms of thrombocytopenia and strategies to treat thrombocytopenia associated with specific agents will provide the clinician with the necessary skills to make proper medical decisions.

Since idiopathic (immune) thrombocytopenic purpura (ITP) in adults is usually a chronic condition with few spontaneous remissions, the goal of treatment is not cure, but to maintain a hemostatically safe platelet level. The indication for treatment should be based not merely on platelet counts, but also clinical indices of bleeding. Although most patients show good initial response to prednisone, the side effects of steroids limit this treatment. Currently, long-term management usually involves splenectomy. Since splenectomy has surgical risks and may also predispose the patient to sepsis, a clinical trial using anti-D (WinRho-SDR) has been performed to determine whether this treatment can safely delay or avoid the need for surgery. The use of WinRho may also reveal the occurrence of spontaneous remissions, a previously unrecognized subgroup of adults with chronic ITP., (Copyright 2002, Elsevier Science Ltd. All rights reserved.)

Abnormalities of plasma von Willebrand factor (VWF) have been recognized to be associated with thrombotic thrombocytopenic purpura (TTP) for over 20 years. Patients with chronic, relapsing TTP have VWF multimers that are larger than normal, similar in size to those secreted by cultured endothelial cells. Recent observations have documented that a deficiency of a VWF-cleaving protease (termed ADAMTS13) may be responsible for the presence of these unusually large VWF multimers. Multiple mutations of the ADAMTS13 gene can result in ADAMTS13 deficiency and cause congenital TTP; autoantibodies neutralizing ADAMTS13 protease activity have been associated with acquired TTP. In Section I, Dr. Evan Sadler reviews the structure, biosynthesis, and function of the ADAMTS13 protease. He describes the mutations that have been identified in congenital TTP and describes the relationship of ADAMTS13 deficiency to the development of both congenital and acquired TTP. Dr. Sadler postulates that the development of TTP may be favored by conditions that combine increased VWF secretion, such as during the later stages of pregnancy, and decreased ADAMTS13 activity. In Section II, Dr. Bernhard Lämmle describes the assay methods for determining ADAMTS13 activity. Understanding the complexity of these methods is essential for understanding the difficulty of assay performance and the interpretation of assay data. Dr. Lämmle describes his extensive experience measuring ADAMTS13 activity in patients with TTP as well as patients with acute thrombocytopenia and severe illnesses not diagnosed as TTP. His data suggest that a severe deficiency of ADAMTS13 activity (< 5%) is a specific feature of TTP. However, he emphasizes that, although severe ADAMTS13 deficiency may be specific for TTP, it may not be sensitive enough to identify all patients who may be appropriately diagnosed as TTP and who may respond to plasma exchange treatment. In Section III, Dr. James George describes the evaluation and management of patients with clinically suspected TTP, as well as adults who may be described as having hemolytic-uremic syndrome (HUS). Dr. George presents a classification of TTP and HUS in children and adults. Appropriate evaluation and management are related to the clinical setting in which the diagnosis is considered. A clinical approach is described for patients in whom the diagnosis of TTP or HUS is considered (1) following bone marrow transplantation, (2) during pregnancy or the postpartum period, (3) in association with drugs which may cause TTP either by an acute immune-mediated toxicity or a dose-related toxicity, (4) following a prodrome of bloody diarrhea, (5) in patients with autoimmune disorders, and (6) in patients with no apparent associated condition who may be considered to have idiopathic TTP. Patients with idiopathic TTP appear to have the greatest frequency of ADAMTS13 deficiency and appear to be at greatest risk for a prolonged clinical course and subsequent relapse. Management with plasma exchange has a high risk of complications. Indications for additional immunosuppressive therapy are described.

Background: Quinine-associated thrombotic thrombocytopenic purpura-hemolytic uremic syndrome (TTP-HUS) is thought to be uncommon and to have a good prognosis., Objective: To describe the frequency, clinical features, and long-term outcomes of quinine-associated TTP-HUS., Design: Case series., Setting: Hospitals in central-western Oklahoma., Patients: 225 consecutive patients with TTP-HUS, 1989-2000., Measurements: Presenting features and clinical outcomes., Results: Thrombotic thrombocytopenic purpura-hemolytic uremic syndrome was associated with quinine in 17 patients. Four patients died, and 7 survivors currently have chronic renal failure. Since 1 July 1995, 132 patients with clinically suspected TTP-HUS were explicitly asked about drug exposure. Fourteen (11%) had taken quinine, and 7 had taken other drugs associated with TTP-HUS. Neurologic abnormalities were as severe in patients with quinine-associated TTP-HUS as in the 118 patients who had not taken quinine., Conclusions: Quinine is a common cause of drug-associated TTP-HUS and can cause death and chronic renal failure. When the disorder is described as TTP-HUS rather than only as HUS, the severity of neurologic abnormalities and the occasional absence of renal failure are emphasized. If recurrent disease is to be prevented, clinicians must recognize quinine as a possible cause.

Prompt recognition of thrombotic thrombocytopenic purpura-hemolytic uremic syndrome (TTP-HUS) and initiation of plasma exchange treatment is critical as it substantially decreases mortality. Nevertheless, death and long-term complications remain common. The recent relaxation of diagnostic criteria has dramatically increased the number of patients treated for clinically suspected TTP-HUS.

Thrombotic thrombocytopenic purpura-hemolytic uremic syndrome (TTP-HUS) is an inclusive term describing diverse syndromes of multiple etiologies with the common features of thrombocytopenia and microangiopathic hemolytic anemia. Other organ involvement, including renal failure, neurologic abnormalities, and gastrointestinal symptoms, is common. Adverse reactions to drugs increasingly are reported as a potential cause of TTP-HUS. More than 50 drugs and other substances have been associated with the development of TTP-HUS, but many case reports are difficult to interpret because there is uncertainty regarding the diagnosis of TTP-HUS and because there is uncertainty regarding the relation of drug exposure to the onset of TTP-HUS. A systematic analysis of reports of drug-associated TTP-HUS will be required to better understand the strength of clinical evidence linking drugs to the etiology of TTP-HUS. In this review, five drugs that have been the subject of the most and the most recent reports of drug-associated TTP-HUS are discussed: mitomycin C, cyclosporine, quinine, ticlopidine, and clopidogrel. The clinical features of TTP-HUS associated with these drugs are different, suggesting two principal mechanisms by which drugs may cause TTP-HUS: dose-related toxicity (mitomycin C, cyclosporine), and immune-mediated reaction (quinine, ticlopidine, clopidogrel). The role of plasma exchange is uncertain, but this treatment is appropriate because of the high mortality and morbidity of drug-associated TTP-HUS. Recognition of a drug-associated etiology in a patient with TTP-HUS is critical to avoid re-exposure and recurrent illness.

Thrombotic thrombocytopenic purpura-hemolytic uremic syndrome (TTP-HUS) is more common in women, and commonly occurs during pregnancy and the immediate postpartum period. An important clinical issue is the distinction of TTP-HUS from the more common obstetric complications, preeclampsia and HELLP syndrome (hemolysis, elevated liver function tests, low platelets). Clinical suspicion of TTP-HUS requires urgent intervention with plasma exchange treatment, a procedure with substantial risk, while preeclampsia and HELLP syndrome typically resolve spontaneously following delivery. Since clinical features of these syndromes can be similar, especially if preeclampsia becomes severe or if seizures (defining eclampsia) occur, the differential diagnosis may be arbitrary. This review addresses the evaluation and management of these syndromes and describes a clinical approach for determining when plasma exchange is appropriate., (Copyright 2001 Wiley-Liss, Inc.)

Therapeutic plasmapheresis may remove platelets as well as plasma. Unintentional platelet loss, if not recognized, may lead to inappropriate patient assessment and treatment. A patient with thrombotic thrombocytopenic purpura-hemolytic uremic syndrome (TTP-HUS) is reported in whom persistent thrombocytopenia was interpreted as continuing active disease; thrombocytopenia resolved only after plasma exchange treatments were stopped. This observation prompted a systematic study of platelet loss with plasmapheresis. Data are reported on platelet loss during 432 apheresis procedures in 71 patients with six disease categories using three different instruments. Comparing the first procedure recorded for each patient, there was a significant difference among instrument types (P<0.001); platelet loss was greater with the Fresenius AS 104 (17.5%, N = 21) than with the COBE Spectra (1.6%, N = 26) or the Haemonetics LN9000 (2.6%, N = 24). With all procedures, platelet loss ranged from 0 to 71%. Among disease categories, platelet loss was greater in patients with dysproteinemias who were treated for hyperviscosity symptoms. Absolute platelet loss with the first recorded apheresis procedure, in the 34 patients who had a normal platelet count before the procedure, was also greater with the AS 104 (2.23 x 10(11) platelets) than with the Spectra (0.29 x 10(11) platelets) or the LN9000 (0.37 x 10(11) platelets). In 39 patients in whom data were collected on consecutive days, platelet removal by plasmapheresis correlated with a decreased patient platelet count (r = 0.40, P = 0.011). In these 39 patients, the platelet counts were significantly decreased at 24 hours (P = 0.002)., (Copyright 2001 Wiley-Liss, Inc.)

Thrombotic thrombocytopenic purpura (TTP) is a potentially fatal disease that is treated with plasma exchange and typically with replacement with fresh frozen plasma (FFP). This approach results in an approximate 50% response rate following 1 week of therapy and 80% survival. Cryoprecipitate poor plasma (CPP) is plasma from which the cryoprecipitate fraction is removed. CPP has been reported to be successful as salvage therapy in refractory TTP and has been suggested to be superior to FFP in retrospective studies. The present report compares initial therapy of TTP with exchange using replacement with either FFP or CPP in a multi-institutional prospective randomized study performed by the North American TTP Group (NATG Group) from 1993 to 1995. Initial therapy also included corticosteroids. Antiplatelet drugs or vinca alkaloids were not employed. A severity score index, response score, and individual clinical parameters (platelet count, LDH x upper limit of normal, hemoglobin level, and creatinine) were compared at their nadir or peak values, baseline, and days +6 and +13 of therapy. Thirteen patients were randomized to FFP exchange and 14 to CPP exchange. Results were equivalent for all parameters. Survival was equal with three deaths in each group. These data indicate that the efficacy of FFP and CPP are the same in the initial treatment of TTP in adults.

Quinine is universally used for the very common symptom of night leg cramps. Patients may not mention it among their medicines, since it is so commonly used and they regulate it themselves. A 68-year-old man suddenly developed extensive bleeding due to severe thrombocytopenia. The diagnosis was initially thought to be a recurrence of idiopathic thrombocytopenic purpura (ITP) that had initially occurred in 1992 and had required splenectomy. Drug-induced thrombocytopenia was also considered, and he was told to stop all of his medicines. Only after three subsequent episodes of severe, symptomatic thrombocytopenia over the next four weeks did he say, upon repeat questioning, that he had continued to take quinine for night leg cramps. Even after a strict warning, he took another quinine tablet that evening, which triggered his fifth episode of severe thrombocytopenia, and confirmed the etiology of quinine-induced thrombocytopenia. The diagnosis thrombocytopenia caused by common drugs can be difficult, requiring persistent, explicit questions.

Thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS) are, in adults, clinically and pathologically indistinguishable except for the severity of renal failure. They are best described as a single disorder, TTP-HUS, because the diagnostic evaluation and initial management are the same. Treatment with plasma exchange, available for more than 20 years, has dramatically altered the course of disease in adults with TTP-HUS. Plasma exchange has improved survival rates from 10% to between 75% and 92%, creating urgency for the initiation of treatment. This has resulted in decreased stringency of diagnostic criteria, which in turn has resulted in a broader spectrum of disorders for which the diagnosis of TTP-HUS is considered. Long-term follow-up has revealed increasing frequencies of relapse and of chronic renal failure. Although the increased survival rate is dramatic and recent advances in understanding the pathogenesis of these syndromes are remarkable, clinical decisions remain empirical. Therefore, the management decisions for patients with suspected TTP-HUS rely on individual experience and opinion, resulting in many different practice patterns. Multipractice clinical trials are required to define optimal management. (Blood. 2000;96:1223-1229)

The ascendancy of EBM has been accompanied by a greater awareness of its shortcomings. It is increasingly evident from the cost, length, and difficulty of performing RCTs that studies cannot be launched to address every question in medicine. Good evidence is often lacking in medicine. Epistomologists question the very notions of evidence and the suitability of current study designs and measurement tools to research the salient issues of concern to patients and others concerned with quality. Lack of evidence of effectiveness does not prove ineffectiveness, yet, in reaction to EBM, insurance companies and government often make this inference to justify decisions to withhold coverage or research support. The unbridled enthusiasm for the evidence-based practice guideline of the early 1990s has been tempered by a more mature understanding of its limitations. Not many practice guidelines are developed well, and the implementation of flawed guidelines can cause harm. The seven-step process outlined earlier is slow, laborious, and expensive (sometimes costing hundreds of thousands of dollars). Moreover, there is little evidence that either the rigor of the methods or the guidelines themselves have a meaningful effect on practice behavior or patient outcomes. To the most cynical observers, the only consistent beneficiaries of guidelines are payers, who use guidelines with considerable success in reducing costs, lengths of stay, and utilization rates. Even ardent advocates of guidelines acknowledge the evidence that disseminating reviews and recommendations, by itself, fails to motivate clinicians to increase delivery of effective interventions and to abandon ineffective ones. This absence of response has stimulated a closer look at the barriers to behavior change and the design of thoughtful implementation strategies that begin with, but reach beyond, simple guidelines. Tools such as reminder systems, standing orders, academic detailing, peer review and audit, feedback, and health system changes recognize that knowing what to do is only one piece of an increasingly complex puzzle. The competitive marketplace of managed health care has added new economic influences on clinician behavior but is also fueling private-sector interest in good research. Patients, clinicians, and policy makers will continue to seek better data concerning what works in medicine and what does not.

Background: With the increased frequency of diagnosis and improved survival of thrombotic thrombocytopenic purpura-hemolytic-uremic syndrome (TTP-HUS), the morbidity of plasma exchange (PE) treatment has become more important., Study Design and Methods: Data were prospectively collected on 71 consecutive patients referred to the Oklahoma Blood Institute (OBI) for PE treatment for clinically suspected TTP-HUS from mid-1996 to mid-1999. Complications were defined as major or minor, and distinguished between those related to central venous catheter access or to the plasma., Results: Twenty-one patients (30%) had 27 major complications, which caused two deaths. The major complications included 2 episodes of hemorrhage after subclavian line insertion (1 death), 1 pneumothorax requiring a chest tube, 12 systemic infections (1 death), 7 episodes of catheter thrombosis requiring removal of the central venous catheter, 2 episodes of venous thrombosis requiring anticoagulant treatment, 2 episodes of hypoxemia and hypotension, and 1 episode of serum sickness. Minor complications occurred in 22 additional patients (31%). Twenty-eight patients (39%) had no complications., Conclusions: The morbidity and mortality of catheter placement and PE are important considerations when PE treatment for clinically suspected TTP-HUS is anticipated.

Chronic refractory idiopathic thrombocytopenic purpura (ITP) is defined as ITP with persistent thrombocytopenia despite conventional initial management with prednisone and splenectomy. Rare in children, It may occur in as many as one third of adults with ITP. The goal of treatment is not cure of the ITP, but only to achieve a safe platelet count, which is arbitrarily assumed to be greater than 30,000 to 50,000/microL. The risk for major bleeding seems great only when the platelet count is less than 10,000/microL. Treatment of patients with moderate thrombocytopenia and no clinically important bleeding symptoms should be avoided. There is no accepted algorithm for management of patients with chronic refractory ITP. Observation without specific treatment must be considered a cornerstone of management. Combination regimens of Immunosuppressive agents may be required for patients with severe and symptomatic thrombocytopenia. Additional supportive care measures are also important.

Platelets, derived from megakaryocyte cytoplasm, have a critical role in normal haemostasis, and in thrombotic disorders. The development of megakaryocytes is controlled by thrombopoietin, which binds to c-mpl on the surface of platelets and megakaryocytes. Platelet membrane glycoproteins mediate binding to subendothelial tissue and aggregation into haemostatic plugs. Thrombocytopenia and disorders of platelet function cause petechiae and mucocutaneous bleeding. Drugs causing specific inhibition of platelet function are important in the treatment of cardiovascular and cerebrovascular disease.

Background: Compression ultrasonography has a high negative predictive value for deep vein thrombosis in symptomatic outpatients. Limited data are available on factors influencing positive predictive value. The objective of this study was to evaluate the positive predictive value of compression ultrasonography according to the anatomic site of vein noncompressibility., Methods: We performed a prospective cohort study of 756 consecutive outpatients with suspected first-episode deep vein thrombosis. Compression ultrasonography was performed at the initial visit: results were abnormal if a noncompressible segment was identified or normal if all segments were fully compressible. Venography was performed in patients with abnormal compression ultrasonography results. Positive predictive value was determined according to the site of noncompressibility: common femoral vein only, popliteal vein only, or both sites. Venography was the reference standard for the presence of deep vein thrombosis., Results: Positive predictive value was 16.7% (95% confidence interval, 0.4%-64.1%) for noncompressibility isolated to the common femoral vein compared with 91.3% (95% confidence interval, 72.0%-98.9%) for the popliteal vein only and 94.4% (95% confidence interval, 72.7%-99.9%) for both sites (P<.001). Of 15 patients with isolated noncompressibility of the common femoral vein, 8 (53%) had pelvic neoplasm or abscess compared with 2 (5%) of 42 with noncompressibility of the popliteal vein only and 6 (13%) of 47 with noncompressibility of both sites (P<.001)., Conclusions: The positive predictive value of noncompressibility isolated to the common femoral vein is too low to be used alone as the diagnostic end point for giving anticoagulant therapy. Noncompressibility isolated to the common femoral vein is a diagnostic marker for pelvic disease.

The goal of treatment for idiopathic (immune) thrombocytopenic purpura (ITP) is to prevent serious bleeding. Traditionally, corticosteroids have been used as first-line therapy followed by splenectomy. Experience with splenectomy over 60 years shows that approximately two thirds of patients achieve normal platelet counts during the initial observation, but that thrombocytopenia often recurs with longer follow-up. We know that long-term use of corticosteroids can lead to significant morbidities; there is no consensus regarding the appropriate timing or indications for splenectomy. To address the Issue of appropriate use of splenectomy, we designed a multicenter clinical trial that will randomize patients to either standard care, involving prednisone followed by splenectomy, or to a novel regimen of limited prednisone treatment followed by WinRho SDF (Nabi, Boca Raton, FL) (anti-D) therapy to maintain the platelet count in a safe range for 1 year. Anti-D can be administered easily in an outpatient setting with few side effects and can provide predictable, transient increases in platelet count. The hypothesis is that prolonged maintenance therapy with a nontoxic regimen may increase the percentage of patients who will experience a spontaneous remission from thrombocytopenia, thereby avoiding an invasive and permanent surgical procedure, splenectomy, and its potentially life-threatening sequelae.

Acquired pure megakaryocytic aplasia is a rare disorder defined by severe thrombocytopenia with no other hematologic abnormalities and absent, or severely decreased marrow megakaryocytes. The etiology may be immune suppression of megakaryocyte development. Two patients are described who both responded rapidly to a combination of antithymocyte globulin and cyclosporine and who remain in remission 13-20 months after discontinuation of cyclosporine. This regimen is well described for treatment of aplastic anemia and may also be effective for acquired pure megakaryocytic aplasia.

Many drugs can induce thrombocytopenia mediated by drug-dependent antiplatelet antibodies. Recent studies have documented specific epitopes for drug-dependent antibody binding on glycoprotein Ib-IX, glycoprotein IIb-IIIa, and platelet-endothelial cell adhesion molecule-1. Molecular identification of antibody binding sites may help to identify susceptible individuals. Management of patients with unexpected thrombocytopenia who are taking multiple drugs remains a difficult clinical problem. A recent systematic review of all published case reports of drug-induced thrombocytopenia ranks drugs according to the strength of clinical evidence for a causal relation to thrombocytopenia. This database is available online at http://moon.ouhsc.edu/jgeorge.

We present a case of a patient who developed all manifestations of thrombotic thrombocytopenic purpura-hemolytic uremic syndrome (TTP-HUS) acutely following treatment of cutaneous T-cell lymphoma (CTCL, Sezary syndrome) with deoxycoformycin (pentostatin). Symptoms and signs included severe thrombocytopenia and microangiopathic hemolytic anemia; hallucinations, confusion and disorientation; oliguric acute renal failure requiring hemodialysis; and fever. No other etiology for these symptoms and signs was present. Complete recovery followed treatment for one month with plasma exchange and glucocorticoids. During the succeeding 20 months she has remained well and her CTCL remains stable on no further treatment. This case and two previously published cases suggest that acute and severe TTP-HUS may be a dose-dependent toxicity of deoxycoformycin (pentostatin)., (Copyright 1999 Wiley-Liss, Inc.)

Our objectives were to measure and compare plasminogen activator inhibitor levels (PAI-1) in primary adult thrombotic thrombocytopenic purpura (TTP) and in secondary TTP associated with bone marrow transplantation (BMT)-TTP. PAI-1 antigen levels were measured by an enzyme linked immunosorbent assay on platelet poor plasma samples obtained from patients at the time of diagnosis of the TTP disorder and from a group of normal volunteers. The samples were frozen at -70 degrees C. Patients with TTP secondary to bone marrow transplantation had their grade determined by percentage fragmented cells and lactate dehydrogenase levels. The primary TTP samples were contributed by investigators in the multi-institutional North American TTP Group, and the bone marrow transplant samples were obtained from an adult bone marrow transplant program. Nineteen patients with adult TTP, and 47 patients with bone marrow transplant-TTP were evaluated. Of the latter, 14 had Grade 2, 13 had Grade 3, and 20 had Grade 4 BMT-TTP. PAI-1 levels were elevated compared to control volunteers in both primary adult TTP and BMT-TTP, P < 0.001. Levels did not differ from normal in Grade 2 BMT-TTP (median = 16 ng/ml; quartiles = 9-20). PAI-1 levels were similar in primary TTP (median = 32 ng/ml; quartiles = 25-51) and Grade 3 BMT-TTP (median = 35 ng/ml; quartiles = 19-48 ng/ml), P = 0.7. However, PAI-1 levels were significantly higher in Grade 4 BMT-TTP (median = 83 ng/ml; quartiles = 60-143) than Grade 3 BMT-TTP, and primary TTP, P < 0.001. PAI-1 levels are high in primary TTP and secondary bone marrow transplant-TTP (Grades 3-4). In contrast, normal levels are seen in Grade 2 BMT-TTP, which is a self-limited disorder. Therefore, high PAI-1 levels may contribute to hypofibrinolysis in the pathogenesis of primary TTP and of moderate to severe TTP (Grades 3-4) following bone marrow transplantation.

Idiopathic thrombocytopenic purpura (ITP, also known as immune thrombocytopenic purpura) in adults is principally a disease of young women. Although in some patients the onset is acute and complete resolution occurs, in most patients, the onset is insidious and the course is chronic. In spite of the relative frequency of ITP, there are important unresolved issues in its diagnosis and management. For this reason, the American Society of Hematology (ASH) chose ITP as the disease topic for its initial sponsored practice guideline in 1993. A major conclusion of the published guideline was the lack of firm evidence on which to base diagnostic procedures and management strategies. This review describes the clinical features of ITP in adults, emphasizes the principal unresolved issues in diagnosis and management, and outlines the critical areas for future research.

Idiopathic thrombocytopenic purpura (ITP, also known as immune thrombocytopenic purpura) affects both children and adults. In childhood, the peak age is 2-4 years, girls and boys are equally affected, and in most children, the disease is self-limited with spontaneous recovery occurring in several weeks to several months. In adults, ITP is most common among young women, and the disease is more insidious in its onset and chronic in its course. In both children and adults, there are important unresolved issues in diagnosis and management that have major cost implications. For this reason, the American Society of Hematology chose ITP as the disease topic for its initial practice guideline in 1993. In 1996, the practice guideline was published in Blood, the Journal of the American Society of Hematology. This review describes the principle features of ITP in children and adults, the process of development of the practice guideline for ITP, and the implications of the guideline for the diagnosis and management of patients with ITP.

Background: Ultrasonography using vein compression accurately detects proximal deep venous thrombosis in symptomatic outpatients. Repeated testing is required for patients with normal results at presentation, but the optimal management of such patients is uncertain., Objective: To test the safety of withholding anticoagulation in outpatients suspected of having first-episode deep venous thrombosis who have normal results on simplified compression ultrasonography at presentation and on a single repeated test done 5 to 7 days later., Design: Prospective cohort study., Setting: Noninvasive vascular laboratories at a university teaching hospital and a Veterans Administration medical center., Patients: 405 consecutive outpatients suspected of having first-episode deep venous thrombosis., Intervention: Ultrasonography was performed at presentation. The common femoral and popliteal veins were assessed for compressibility. If the result was normal, anti-coagulation was withheld and testing was repeated 5 to 7 days later. Anticoagulation was withheld from all patients whose results remained normal according to compression ultrasonography, regardless of their symptoms. The safety of this approach was tested by follow-up lasting 3 months., Measurements: Objective testing was done during follow-up in all patients with symptoms or signs of venous thromboembolism. The outcome measure was symptomatic venous thrombosis or pulmonary embolism during follow-up, confirmed by objective testing., Results: Ultrasonography had normal results in 335 patients (83%) and abnormal results in 70 (17%). None of the patients with normal results died of pulmonary embolism. Venous thromboembolism occurred during follow-up in 2 patients with normal ultrasonographic results (0.6% [95% CI, 0.07% to 2.14%]) and in 4 patients with abnormal results (5.7% [CI, 1.58% to 13.99%]) (P = 0.009)., Conclusions: It is safe to withhold anticoagulation in outpatients suspected of having first-episode deep venous thrombosis if results of simplified compression ultrasonography are normal at presentation and on a single repeated test done 5 to 7 days later.

Thrombotic thrombocytopenic purpura-hemolytic uremic syndrome (TTP-HUS) is a clinical syndrome defined by the presence of thrombocytopenia and microangiopathic hemolytic anemia without a clinically apparent etiology. Patients may also have multiple other symptoms and signs including neurologic and renal abnormalities and fever. In the era prior to effective therapy with plasma exchange, most patients developed multisystem abnormalities and the syndrome was more easily recognized. Now, since there is urgency to begin treatment, sufficient diagnostic criteria for TTP-HUS are only thrombocytopenia and microangiopathic hemolytic anemia without a clinically apparent cause; patients may have no neurologic symptoms, renal abnormalities, or fever. This has lead to an apparent increased incidence because of both the increased importance of early recognition and the decreased specificity of the diagnostic criteria. Effective treatment has also revealed new aspects of the clinical course of TTP-HUS following the initial response to plasma exchange treatment: prompt exacerbations, which are common when plasma exchange is diminished in frequency or discontinued, and later relapses, which may occur many years after the initial episode. This review describes the evolution of the syndrome of TTP-HUS in the current era of effective treatment, and describes the management and clinical outcomes among patients treated by the Oklahoma Blood Institute.

Idiopathic thrombocytopenic purpura (ITP) is a disorder that has distinct clinical manifestations in children and adults. In children, ITP is typically abrupt in onset and self-limited in its course. Girls and boys are equally affected. In adults, ITP is typically more indolent in its onset and the course is persistent, often lasting many years or characterized by recurrent exacerbations of disease. Most patients are young women. Intracerebral hemorrhage, while rare, is the most common cause of death in children and adults with ITP. In both children and adults, the ITP is assumed to be caused by antibody-mediated platelet consumption, where Fc receptors on the macrophage bind to antibody-coated platelets resulting in an accelerated platelet destruction. However, tests for antiplatelet antibodies have not yet been established as clinically useful for management decisions. The natural history and long-term prognosis of adults with ITP remain incompletely defined.

The acute-phase response is believed to be an important systemic defence reaction to inflammation during infection, trauma, injury or neoplasia. Although the interleukin-6 (IL-6) family of cytokines appear to be the major regulators of the acute-phase reaction, the exact biological significance of this process remains unknown. In this study, a panel of monoclonal antibodies (Mabs) was raised against the extracellular domain of human gp130 (the common signal transducing chain of the IL-6 cytokine family) in order to inhibit the biological activity of IL-6-like cytokines in vivo. Mabs designated 4B11 and 2H4 were most effective in the inhibition of the in vitro acute-phase response on hepatoma cells and prevented the IL-6-induced growth inhibition of A375 cells. Administration of the antibodies to dogs at a dosage of 8 mg/kg/d showed that 2H4 was a potent inhibitor of the IL-6-induced (40 micrograms/kg/d) acute-phase response, abrogating IL-6-mediated increments in fibrinogen, C-reactive protein and the platelet count. This antibody, the first described to abrogate the acute-phase response in vivo, may not only permit development of a new anti-inflammatory strategy, but provides an excellent tool for defining the function of acute-phase proteins in inflammation and infection.

Endothelial damage is thought to be a contributing factor in the pathogenesis of Thrombotic Thrombocytopenic Purpura/Hemolytic Uremic Syndromes (TTP/HUS). The present studies measured two markers of endothelial cell stimulation and/or activation [von Willebrand Factor (vWF:Ag) and thrombomodulin (TM)] in patients with TTP/HUS disorders and compared them to controls. The patient groups consisted of adults with TTP/HUS, with (n = 13) and without (n = 14) peak Cr levels >2.0 mg/dl. Additionally, 52 patients with Bone Marrow Transplant-associated Thrombotic Microangiopathy (BMT-TM) following allogeneic BMT were evaluated. Both vWF:Ag and TM were elevated in all patient groups compared to controls. TTP/HUS patients with peak Cr >2.0 mg/dl had higher TM levels (P < 0.001) than did those with peak Cr levels below 2 mg/dl. However, thrombomodulin/ creatinine (TM/Cr) ratios did not differ in these two groups nor did they differ from controls. BMT-TM pts had higher vWF:Ag levels and higher TM/Cr ratios than controls and TTP/ HUS, P < 0.001. The median TM/Cr ratio in BMT-TM was 91 (range = 34-229) compared to 38 (range = 29-50) in controls, P < 0.001 and 38 (range = 6 to 156) in TTP/HUS, P < 0.001. Additionally both TM (P < 0.001) and TM/Cr (P < 0.02) were higher in patients with Grades 3 and 4 BMT-TM compared to those with Grade 2 BMT-TM. These results suggest that endothelial cell activation occurs in TTP/HUS and BMT-TM. Since TM/Cr ratios were higher in BMT-TM compared to TTP/HUS, these findings suggest that the mechanism of elevated TM in BMT-TM cannot be explained solely by altered renal excretion. Taken together, these findings strongly indicate a role of endothelial cell damage in BMT-TM.

Idiopathic thrombocytopenic purpura is a common acquired bleeding disorder. However, the diagnosis is often uncertain because there are no specific tests that define idiopathic thrombocytopenic purpura, and management decisions are often difficult because there are no firm data to define the clinical course and to estimate the risks of major bleeding and death. Because the incidence of idiopathic thrombocytopenic purpura is greatest in young women, its occurrence during pregnancy is a frequent problem, with specific issues related to the anticipated route of delivery and the risks for neonatal thrombocytopenia. To address these unresolved issues, the American Society of Hematology established a panel to develop a practice guideline for idiopathic thrombocytopenic purpura. The data from this recently published document and its recommendations are summarized in this review.

The anion dependence of [3H]bumetanide binding and 22Na+ transport by the rabbit parotid Na(+)-K(+)-2Cl- co-transporter was studied in acinar basolateral membrane vesicles (BLMVs). Cl-, Br- and NO3- have a biphasic effect on binding consistent with the presence of two anion sites associated with the bumetanide binding event, a high-affinity stimulatory site and a lower-affinity inhibitory site. We show that formate shares only the stimulatory site and SO4(2-) only the inhibitory site. The initial rate of [3H]bumetanide binding was stimulated by formate or low [Cl-] and inhibited by SO4(2-) or high [Cl-], but the rate of [3H]bumetanide dissociation was not affected by the presence of these anions in the dissociation medium. However, when [3H]bumetanide was bound to BLMVs in the presence of formate its rate of dissociation was more than four times faster than when binding took place in the presence of Cl-. These observations indicate that the binding of bumetanide and the stimulatory anion are ordered such that the anion must necessarily bind first and subsequently cannot dissociate until after bumetanide dissociates. In zero-trans-flux experiments, extravesicular SO4(2-) and formate had no effect on 22Na+ transport via the co-transporter [Turner and George (1988) J. Membr. Biol. 102, 71-77]. Thus neither of the anion sites associated with bumetanide binding is a Cl- transport site. However, we show here that SO4(2-) inhibits transport when present in the intravesicular space. Since the BLMV preparation is predominantly oriented cytosolic-side-in, this observation indicates the existence of an inhibitory cytosolic anion modifier site. Our data suggest that this site is identical to the inhibitory anion site associated with bumetanide binding.

Dog and human fibrinogen were derivatized with N-hydroxysuccinimido-fluorescein and utilized for flow cytometric estimation of fibrinogen binding to activated platelets. Fluorescein-fibrinogen binding fulfilled the criteria for specific binding to platelets; the binding was saturable, dependent on agonist activation, and inhibited by unlabeled fibrinogen. In addition, EDTA and barbourin, a KGD-containing peptide, were found to inhibit the binding of fluorescein-fibrinogen. Fluorescein-fibrinogen bound to dog platelets with an apparent affinity of 0.31 microM after stimulation with either adenosine-5'-diphosphate (ADP) or plateletactivating factor. The labeled fibrinogen was also used to study the fibrinogen binding capacity of aged, biotinylated platelets. Aged platelets were indistinguishable from young platelets with regard to fibrinogen binding in response to ADP. These studies document that direct derivatization of fibrinogen with fluorescein generates a useful probe for analyzing fibrinogen binding to platelets with flow cytometry.

The in vivo life span of dog platelets was determined by derivatizing whole blood with N-hydroxysuccinimido biotin, reinfusing the biotinylated blood and subsequently monitoring the survival of the biotinylated platelets with flow cytometry. We found that the biotinylated platelets had a mean life span of 6.0 +/- 1.1 d as determined by curve-fitting the platelet disappearance data to gamma functions. These data are in good agreement with literature values of platelet life span for canine platelets labelled with either 111Indium-oxine or 51Chromium. Biotinylated platelets were analysed after reinfusion and found to aggregate normally in response to the agonists adenosine diphosphate and phorbol myristate acetate. These experiments demonstrate that biotinylated platelets survive normally in vivo and that this labelling method can be used for determining platelet life spans.

We demonstrate the presence of a 160 kD protein in rabbit parotid basolateral membranes that can be labeled with the irreversible sulfhydryl reagent [14C]-N-ethylmaleimide in a bumetanide-protectable fashion. The specificity of this labeling, and our previous evidence for the existence of an essential sulfhydryl group closely associated with the bumetanide-binding site on the parotid Na(+)-K(+)-Cl-cotransporter (J. Membrane Biol. 112:51-58, 1989), provide strong evidence that this protein is a part or all of the parotid bumetanide-binding site. When this protein is treated with endoglycosidase F/N-glycosidase F to remove N-linked oligosaccharides, its apparent molecular weight decreases to 135 kD. The pI of this deglycosylated protein is approximately 6.4. The bumetanide-binding protein was purified using two preparative electrophoresis steps. First, a Triton X-100 extract enriched in this protein was run on preparative electrophoresis to obtain fractions containing proteins in the 160 kD range. These were then deglycosylated with endoglycosidase F/N-glycosidase F and selected fractions were pooled and rerun on preparative electrophoresis to obtain a final 135 kD fraction. The enrichment of the bumetanide-binding protein in this final 135 kD fraction estimated from [14C]-N-ethylmaleimide labeling was approximately 48 times relative to the starting membrane extract. Since the bumetanide-binding site represents approximately 2% of the total protein in this starting extract, this enrichment indicates a high degree of purity of this protein in the 135 kD fraction.

The literature on membrane glycoprotein changes occurring during platelet storage is reviewed. Technical problems which may have biased reports are clarified, and the consensus of current studies is established. The membrane alterations that occur during blood bank storage are reminiscent of the surface changes which result from platelet secretion: an increased surface concentration of GP IIb-IIIa and GMP-140, and the appearance of platelet membrane microparticles in the supernatant plasma. The clinical importance of these changes is unknown. Future directions for research on the structure and function of stored platelets are discussed.

Platelet IgG has been studied primarily to develop an aid for clinical diagnosis--a search that has proven elusive (48). However, studies of the interaction of IgG and other plasma proteins with platelets have provided new insight into the intracellular pathways for the acquisition of proteins into regulated secretory granules. From a clinical perspective, it is important not to make the assumption that all platelet IgG is antiplatelet antibody. Data on platelet IgG must be distinguished between measurements of alpha-granule IgG, which comprises almost all of the total platelet IgG content, and platelet surface IgG, representing less than 1 percent of total platelet IgG. alpha-granule IgG does not appear to be antiplatelet antibody; platelet surface IgG is likely to be at least partly antiplatelet antibody. The total platelet (alpha-granule) content of IgG mirrors the concentration and composition of plasma IgG. It is increased in patients with hypergammaglobulinemia of any cause and absent in agammaglobulinemia. The platelet alpha-granule content of IgG, IgA, and albumin is proportional to their concentrations in plasma, and the platelet content of IgG, IgA and albumin also reflects their plasma concentration over a wide range of plasma abnormalities. These observations suggest that platelets acquire IgG, IgA, and albumin by fluid phase endocytosis. Total platelet IgG is consistently increased in patients with ITP and is also commonly increased in patients with thrombocytopenia due to increased platelet destruction of apparently nonimmune mechanisms. The total platelet IgG content does not appear to be increased in patients who have thrombocytopenia due to marrow failure. Therefore, the measurement of total platelet IgG may be analogous to the reticulocyte count, which is increased in patients who have accelerated erythropoiesis caused by either immune or nonimmune hemolytic anemia. The increased concentration of total platelet IgG in patients with ITP is parallel to the appearance of larger platelets produced during the stress of increased thrombopoietic stimulation. Therefore, determinations of mean platelet volume may yield clinical information equivalent to the measurement of total platelet IgG. The concentration of platelet surface IgG is greatly increased in patients with ITP, and concentrations are highest in patients with the most acute ITP. Platelet surface IgG may represent antiplatelet antibody in these patients. However, for unknown reasons, modest elevations of platelet surface IgG are found in many patients with nonimmune thrombocytopenia.(ABSTRACT TRUNCATED AT 400 WORDS)

We demonstrate that the high affinity bumetanide binding site of the rabbit parotid acinar cell can be extracted from a basolateral membrane fraction using relatively low concentrations (0.07%, wt/vol; 1 mg membrane protein/ml) of the nonionic detergent Triton X-100. This extracted site cannot be sedimented by ultracentrifugation at 100,000 x g x 1 hr. Bumetanide binding to this site retains the ionic characteristics of bumetanide binding to native membranes but shows a fivefold increase in binding affinity (Kd = 0.57 +/- 0.15 microM vs. Kd = 3.3 +/- 0.7 microM for native membranes). Inactivation of the extracted bumetanide binding site observed at detergent/protein ratios greater than 1 can be prevented or (partially) reversed by the addition of exogenous lipid (0.2% soybean phosphatidylcholine). When the 0.07% Triton extract is fractionated by sucrose density gradient centrifugation in 0.24% Triton X-100, 0.2% exogenous lipid and 200 mM salt, the high affinity bumetanide binding site sediments as a single band with S20,w = 8.8 +/- 0.8 S. This corresponds to a molecular weight approximately 200 kDa for the bumetanide binding protein-detergent-lipid complex and represents a sevenfold purification of this site relative to the starting membrane fraction. In contrast to previous attempts to purify Na/K/Cl cotransport proteins and their associated bumetanide binding sites, the present method avoids harsh detergent treatment as well as direct covalent modification (inactivation) of the transporter itself. As a consequence, one can follow the still active protein through a series of extraction and purification steps by directly monitoring its bumetanide binding properties.

Platelets are believed to play a role in the pathogenesis of atherosclerosis and of the vascular obstruction that causes the acute complications of coronary artery disease. Since specific behavioral patterns appear to be related to the development of coronary artery disease and since emotional stress may predispose an individual to acute cardiovascular ischemia, it was hypothesized that platelet activation by catecholamines might be involved in these events. To study emotional stress, plasma samples were obtained from 61 senior medical residents immediately before they were to speak in public. There were significant increases in the plasma concentrations of the platelet-secreted proteins platelet factor 4 and beta-thromboglobulin and epinephrine and norepinephrine immediately before speaking, which demonstrates that platelet activation and secretion occur in association with this type of emotional stress. Four trials were carried out to study the mechanism for this observed platelet secretion: (1) phenoxybenzamine, (2) propranolol, (3) 650 mg aspirin, and (4) 80 mg aspirin were given several hours before the public speaking engagement. Neither phenoxybenzamine nor propranolol in doses that blocked the hemodynamic effects of alpha 1- and beta 1-adrenergic stimulation modified platelet secretion. Aspirin also did not block platelet secretion, which suggests that platelets were not being stimulated through a cyclooxygenase-dependent pathway. This study provides direct evidence of platelet secretion in vivo in association with emotional stress, and underscores the potential importance of platelet activation and secretion in the acute events that occur in patients with vascular disease.