Richard Lottenberg

Management of Sickle Cell Disease: Summary of the 2014 Evidence-Based Report by Expert Panel Members

IMPORTANCE Sickle cell disease (SCD) is a life-threatening genetic disorder affecting nearly 100,000 individuals in the United States and is associated with many acute and chronic complications requiring immediate medical attention. Two disease-modifying therapies, hydroxyurea and long-term blood transfusions, are available but underused. OBJECTIVE To support and expand the number of health professionals able and willing to provide care for persons with SCD. EVIDENCE REVIEW Databases of MEDLINE (including in-process and other nonindexed citations), EMBASE, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, CINAHL, TOXLINE, and Scopus were searched using prespecified search terms and keywords to identify randomized clinical trials, nonrandomized intervention studies, and observational studies. Literature searches of English-language publications from 1980 with updates through April 1, 2014, addressed key questions developed by the expert panel members and methodologists. FINDINGS Strong recommendations for preventive services include daily oral prophylactic penicillin up to the age of 5 years, annual transcranial Doppler examinations from the ages of 2 to 16 years in those with sickle cell anemia, and long-term transfusion therapy to prevent stroke in those children with abnormal transcranial Doppler velocity (≥200 cm/s). Strong recommendations addressing acute complications include rapid initiation of opioids for treatment of severe pain associated with a vasoocclusive crisis, and use of incentive spirometry in patients hospitalized for a vasoocclusive crisis. Strong recommendations for chronic complications include use of analgesics and physical therapy for treatment of avascular necrosis, and use of angiotensin-converting enzyme inhibitor therapy for microalbuminuria in adults with SCD. Strong recommendations for children and adults with proliferative sickle cell retinopathy include referral to expert specialists for consideration of laser photocoagulation and for echocardiography to evaluate signs of pulmonary hypertension. Hydroxyurea therapy is strongly recommended for adults with 3 or more severe vasoocclusive crises during any 12-month period, with SCD pain or chronic anemia interfering with daily activities, or with severe or recurrent episodes of acute chest syndrome. A recommendation of moderate strength suggests offering treatment with hydroxyurea without regard to the presence of symptoms for infants, children, and adolescents. In persons with sickle cell anemia, preoperative transfusion therapy to increase hemoglobin levels to 10 g/dL is strongly recommended with a moderate strength recommendation to maintain sickle hemoglobin levels of less than 30% prior to the next transfusion during long-term transfusion therapy. A strong recommendation to assess iron overload is accompanied by a moderate strength recommendation to begin iron chelation therapy when indicated. CONCLUSIONS AND RELEVANCE Hydroxyurea and transfusion therapy are strongly recommended for many individuals with SCD. Many other recommendations are based on quality of evidence that is less than high due to the paucity of clinical trials regarding screening, management, and monitoring for individuals with SCD.

[28] Assay of coagulation proteases using peptide chromogenic and fluorogenic substrates

Publisher Summary Amino acid chromogenic and fluorogenic substrates have been used for many years for assaying proteases. The sensitivity of the assay procedures that employ these substrates and the convenience of spectrophotometric or fluorometric measurements has led to their widespread use. Most of the early amino acid chromogenic and fluorogenic substrates are highly selective for the primary specificity-determining (P1) amino acid; thus substrates such as benzoylarginine-p-nitroanilide, for assaying trypsin-like proteases, as well as aromatic amino acidp-nitrophenyl esters for chymotrypsin-like proteases, have been extensively investigated and employed for routine proteolytic enzyme assay. The recognition that both the selectivity of many proteases and their catalytic efficiency depend on interactions with subsite amino acids in the peptide substrate coupled with the availability of amino acid sequences around the cleavage sites in several zymogens of the coagulation and fibrinolytic systems has led to the synthesis and commercial availability of a variety of peptide chromogenic and fluorogenic substrates with much greater selectivity than the single amino acid chromogenic and fluorogenic substrates.

Acquired Hemophilia: A Natural History Study of 16 Patients With Factor VIII Inhibitors Receiving Little or No Therapy

Rarely, a patient develops an antibody against factor VIII coagulant activity. The resultant hemorrhagic diathesis is clinically distinct from inherited hemophilia, being characterized by few hemarthroses but frequent skin and other soft-tissue hematomas. Hematuria may be troublesome. These patients represent therapeutic challenges. This study is one institutions results with 16 such patients followed up over an average of 31 months (range, four to 120 months; median, 19 months). It describes the largest group from a single institution receiving essentially no immunosuppressive agents, yet has one of the better overall results. Two patients experienced fatal hemorrhage and five patients underwent spontaneous remission. Long-term survival is not incompatible with persistence of the inhibitor. We conclude that this hemorrhagic diathesis is clinically distinct, less fatal than usually perceived, and may undergo spontaneous remission. Clearly, there is no mandate for any particular therapeutic regimen, such as immunosuppression, in the attempt to rid the patient of the antibody.

Capturing host plasmin(ogen): a common mechanism for invasive pathogens?

Plasmin is a potent enzyme that can dissolve blood clots and degrade extracellular matrix proteins. A number of pathogenic bacteria produce plasminogen activators. Many of these organisms can also bind plasmin(ogen) to surface receptors and protect the active enzyme from physiological inhibition. Cell-surface localization of plasmin may be a common mechanism used by bacteria to facilitate movement through normal tissue barriers.

Anti-CD20 monoclonal antibody (rituximab) therapy for acute cardiac humoral rejection: a case report.

Humoral or antibody-mediated rejection in cardiac transplant recipients is mediated by donor-specific cytotoxic antibodies and is histologically defined by linear deposits of immunoglobulin and complement in the myocardial capillaries. Antibody-mediated rejection often is accompanied by hemodynamic compromise and is associated with reduced long-term graft survival. Standard immunosuppression, designed to target T cell immune function, is largely ineffective against this B cell-driven process. Current treatment options for humoral rejection are limited by a lack of specific anti-B cell therapies. We present the case of a 50-year-old woman with hemodynamically significant humoral rejection resistant to steroids, cyclophos-phamide, and plasmapheresis who responded to the addition of anti-CD20 monoclonal antibody therapy (rituximab). One year posttransplant, the patient is rejection-free, with normal left ventricular systolic function and coronary arteries.

The action of thrombin on peptide p-Nitroanilide substrates

Kinetic parameters for the action of bovine alpha-thrombin on 24 commercially available peptide p-nitroanilides have been determined. The selectivity constant, kcat/Km, ranges from 3.3 X 10(1) to 1.1 X 10(8) M-1 X S-1 for the poorest and the best substrates, respectively. The best substrates for thrombin were identified as those with arginine in the P1 position, proline or a proline homolog in the P2 position, and an apolar amino acid in the P3 position. Quantitative distinction between lysine and arginine in the P1 position and other amino acids in the P2-P4 positions of the substrate is reported from the changes in the kinetic parameters for substrates differing in only a single amino acid in these positions. Effects of NaCl, CaCl2 and poly(ethylene glycol) concentrations, pH and temperature on the action of thrombin on selected substrates have been assessed. A source of large systematic error in thrombin concentration estimates was identified as resulting from adsorption losses. These losses were eliminated by inclusion of poly(ethylene glycol) in dilution and reaction buffers.

Survival of trauma patients after massive red blood cell transfusion using a high or low red blood cell to plasma transfusion ratio.

Objective: Early and aggressive treatment of trauma-associated coagulopathy through transfusion of high plasma to packed red blood cell ratios is gaining favor. Whether this strategy is associated with improved survival is unclear. We performed a systematic review to determine whether higher plasma to packed red blood cell ratios compared with lower plasma to packed red blood cell ratios were associated with a survival advantage. Data Sources: We searched electronic databases MEDLINE, Embase, and Web of Science from 1950 to February 2010 for studies comparing mortality in massively transfused trauma cohorts receiving different plasma to packed red blood cell ratios. Study Selection: Two reviewers independently performed study selection. Discrepancies in study selection were resolved by discussion and consensus. Data Extraction: Two reviewers independently extracted data from each study using a standardized form. Two authors independently assessed study quality using the Newcastle-Ottawa Scale. Data Synthesis: Eleven observational studies and no randomized controlled trials were identified. Three studies found a survival benefit with a 1:1 plasma to packed red blood cell transfusion ratio compared with either higher or lower ratios. Six studies did not examine a 1:1 ratio but concluded that higher plasma to packed red blood cell ratios improved survival. Secondary outcomes, including multiorgan system failure, packed red blood cell transfusion, respiratory outcomes, and coagulation variables, did not uniformly favor 1:1 or higher plasma to packed red blood cell ratios. Conclusions: Methodological flaws, including survival bias, and heterogeneity between studies preclude statistical comparisons concerning the effects of a 1:1 plasma to packed red blood cell transfusion ratio. There is insufficient evidence to support a survival advantage with a 1:1 plasma to packed red blood cell transfusion strategy. Randomized controlled trials evaluating safety and efficacy are warranted before a high plasma to packed red blood cell transfusion ratio can be recommended.

The action of Factor Xa on peptide p-nitroanilide substrates: substrate selectivity and examination of hydrolysis with different reaction conditions

Kinetic parameters for the action of bovine Factor Xa (EC 3.4.21.22) on 25 commercially available peptide p-nitroanilides have been determined. The selectivity constant, kc/Km, ranges from 1.5 X 10(1) to 2 X 10(6) M-1 X s-1 for the poorest and the best substates, respectively. The best substrates for Factor Xa were identified as those with arginine in the P1 position, and glycine in the P2 position. Quantitative distinction between lysine and arginine in the P1 position and other amino acids in the P2-P4 positions of the substrate is reported from the changes in the kinetic parameters for substrates differing in only a single amino acid in these positions. Effect of NaCl and CaCl2 concentrations and temperature on the action of Factor Xa on selected substrates have been assessed. Km values for Factor Xa hydrolysis of most substrates are greater than 100 microM. Solubility of the substrates consequently restricts measurements of reaction velocities to concentrations lower than desirable for optimally determining kc. Comparison of these kinetic parameters for Factor Xa with those of thrombin (Lottenberg, R., Hall, J.A., Blinder, M., Binder, E. and Jackson, C.M. (1983) Biochim. Biophys. Acta 742,539-557) for these same substrates indicates that the greater hydrolytic efficiency of thrombin is due primarily to lower Km values.

Pulmonary embolism prophylaxis with inferior vena cava filters in trauma patients: a systematic review using the meta-analysis of observational studies in epidemiology (MOOSE) guidelines

Prophylactic inferior vena cava filters (pIVCFs) for the prevention of pulmonary embolism (PE) are controversial. Current practice guidelines (EAST and ACCP) are based on the critical appraisal of observational studies. As a result, their recommendations are conflicting and may account for practice pattern variation. The purpose of this study is to critically review the available literature and ascertain the level of evidence both for and against the use of pIVCFs for PE prophylaxis in trauma patients. We searched PubMed and Web of Science for publications from 1950 until July 2010 that assessed the efficacy of PE prevention with pIVCFs in the trauma population. We followed the MOOSE (Meta-analysis of Observational Studies in Epidemiology) guidelines for design, implementation, and reporting. The Newcastle-Ottawa Score was used for quality and comparability assessment. Seven observational studies met inclusion criteria for this meta-analysis, representing 1,900 patients. Only one study was published in this decade. The rate of PE was statistically lower in the IVCF group compared to a matched control group without IVCFs (OR 0.21, 95% CI 0.09–0.49). There was no significant difference in DVT. Using the MOOSE criteria these results show a decreased likelihood of PE among trauma patients who receive pIVCFs. Although these results could favor the placement of pIVCFs, the lack of contemporary use of pharmacologic prophylaxis across studies does not allow us to make firm conclusions either for or against the routine use of pIVCFs. Prospective randomized trials are needed to determine the role of pIVCFs in high-risk trauma patients.

Analysis of the interaction of group A streptococci with fibrinogen, streptokinase and plasminogen

Group A streptococci demonstrate a number of distinct ways to interact with the human fibrinolytic system to acquire unregulatable cell-surface enzymatic activity. Interactions between bacteria, fibrinogen, streptokinase and plasminogen resulted in acquisition of cell-associated enzymatic activity that can lyse fibrin clots despite the presence of the major physiological plasmin inhibitor, alpha 2-antiplasmin. Western blot analysis of extracted streptococcal surface proteins suggested that binding of fibrinogen to M or M-related proteins mediated the capture of streptokinase-plasminogen complexes to the bacteria. The enzymatic complex formed by reaction of bacteria with fibrinogen, streptokinase and plasminogen was found to be more stable in human plasma than pre-formed plasmin bound directly to the same bacteria strain.