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Michael R DeBaun,
Sharada A Sarnaik,
Mark J Rodeghier,
Caterina P Minniti,
Thomas H Howard,
Rathi V Iyer,
Baba Inusa,
Paul T Telfer,
Melanie Kirby-Allen,
Charles T Quinn, [......],
Corina E Gonzalez,
Suzanne L Saccente,
Karen A Kalinyak,
John J Strouse,
Jason M Fixler,
Mae O Gordon,
J Phillip Miller,
Michael J Noetzel,
Rebecca N Ichord,
James F Casella
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ABSTRACT: The most common form of neurologic injury in sickle cell anemia (SCA) is silent cerebral infarction (SCI). In the Silent Cerebral Infarct Multi-Center Clinical Trial, we sought to identify risk factors associated with SCI. In this cross-sectional study, we evaluated the clinical history and baseline laboratory values and performed magnetic resonance imaging of the brain in participants with SCA (HbSS or HbSβ° thalassemia) between the ages of 5 and 15 years with no history of overt stroke or seizures. Neuroradiology and neurology committees adjudicated the presence of SCI. SCIs were diagnosed in 30.8% (251 of 814) participants who completed all evaluations and had valid data on all prespecified demographic and clinical covariates. The mean age of the participants was 9.1 years, with 413 males (50.7%). In a multivariable logistic regression analysis, lower baseline hemoglobin concentration (P < .001), higher baseline systolic blood pressure (P = .018), and male sex (P = .030) were statistically significantly associated with an increased risk of an SCI. Hemoglobin concentration and systolic blood pressure are risk factors for SCI in children with SCA and may be therapeutic targets for decreasing the risk of SCI. This study is registered at www.clinicaltrials.gov as #NCT00072761.
Blood 11/2011; 119(16):3684-90. · 9.90 Impact Factor
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Janet L Kwiatkowski,
Alan R Cohen,
Julian Garro,
Ofelia Alvarez,
Ramamorrthy Nagasubramanian,
Sharada Sarnaik,
Alexis Thompson, Gerald M Woods,
William Schultz,
Nicole Mortier,
Peter Lane,
Brigitta Mueller,
Nancy Yovetich,
Russell E Ware
American Journal of Hematology 10/2011; · 4.67 Impact Factor
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ABSTRACT: Increased arginase activity in the vasculature has been implicated in the regulation of nitric oxide (NO) homeostasis, leading to the development of vascular disease and the promotion of tumor cell growth. Recently, we showed that cysteine, in the presence of iron, promotes arginase activity by driving the Fenton reaction. In the present report, we showed that induction of oxidative stress in erythroleukemic cells with the thiol-specific oxidant, diamide, led to an increase in arginase activity by 42% (P = 0.02; vs. control). By using specific antibodies, it was demonstrated that this increase correlated with an increase in arginase-1 levels in the cells and with corresponding decreases in glutathione and protein thiol levels. Treatment of cells with aurothiomalate (ATM), a protein thiol-complexing agent, diminished the activity of arginase and arginase-1 levels by 19.5 and 35.2%, respectively (vs. control) and significantly decreased both glutathione and protein thiol levels, further implicating the thiol redox system in the cellular activation of arginase. Furthermore, diamide significantly altered the kinetics of arginase, resulting in the doubling of its V(max) (vs. control). Our presented data demonstrate, for the first time that the intracellular arginase activation is may be enhanced in part, via a cellular thiol-mediated mechanism.
Molecular and Cellular Biochemistry 09/2011; 360(1-2):159-68. · 2.06 Impact Factor
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Daniel P Heruth,
Troy Hawkins,
Derek P Logsdon,
Margaret I Gibson,
Inna V Sokolovsky,
Ndona N Nsumu,
Stephanie L Major,
Barbara Fegley, Gerald M Woods,
Karen B Lewing,
Kathleen A Neville,
Kenneth Cornetta,
Kenneth R Peterson,
Robert A White
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ABSTRACT: KLF1 regulates definitive erythropoiesis of red blood cells by facilitating transcription through high affinity binding to CACCC elements within its erythroid specific target genes including those encoding erythrocyte membrane skeleton (EMS) proteins. Deficiencies of EMS proteins in humans lead to the hemolytic anemia Hereditary Spherocytosis (HS) which includes a subpopulation with no known genetic defect. Here we report that a mutation, E339D, in the second zinc finger domain of KLF1 is responsible for HS in the mouse model Nan. The causative nature of this mutation was verified with an allelic test cross between Nan/+ and heterozygous Klf1(+/-) knockout mice. Homology modeling predicted Nan KLF1 binds CACCC elements more tightly, suggesting that Nan KLF1 is a competitive inhibitor of wild-type KLF1. This is the first association of a KLF1 mutation with a disease state in adult mammals and also presents the possibility of being another causative gene for HS in humans.
Genomics 11/2010; 96(5):303-7. · 3.02 Impact Factor
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Monica L Hulbert,
Robert C McKinstry,
JoAnne L Lacey,
Christopher J Moran,
Julie A Panepinto,
Alexis A Thompson,
Sharada A Sarnaik, Gerald M Woods,
James F Casella,
Baba Inusa,
Jo Howard,
Fenella J Kirkham,
Kofi A Anie,
Jonathan E Mullin,
Rebecca Ichord,
Michael Noetzel,
Yan Yan,
Mark Rodeghier,
Michael R Debaun
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ABSTRACT: Children with sickle cell disease (SCD) and strokes receive blood transfusion therapy for secondary stroke prevention; despite this, approximately 20% experience second overt strokes. Given this rate of second overt strokes and the clinical significance of silent cerebral infarcts, we tested the hypothesis that silent cerebral infarcts occur among children with SCD being transfused for secondary stroke prevention. A prospective cohort enrolled children with SCD and overt strokes at 7 academic centers. Magnetic resonance imaging and magnetic resonance angiography of the brain were scheduled approximately every 1 to 2 years; studies were reviewed by a panel of neuroradiologists. Eligibility criteria included regularly scheduled blood transfusion therapy. Forty children were included; mean pretransfusion hemoglobin S concentration was 29%. Progressive cerebral infarcts occurred in 45% (18 of 40 children) while receiving chronic blood transfusion therapy; 7 had second overt strokes and 11 had new silent cerebral infarcts. Worsening cerebral vasculopathy was associated with new cerebral infarction (overt or silent; relative risk = 12.7; 95% confidence interval, 2.65-60.5, P = .001). Children with SCD and overt strokes receiving regular blood transfusion therapy experience silent cerebral infarcts at a higher rate than previously recognized. Additional therapies are needed for secondary stroke prevention in children with SCD.
Blood 10/2010; 117(3):772-9. · 9.90 Impact Factor
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Thomas V Adamkiewicz,
Miguel R Abboud,
Carole Paley,
Nancy Olivieri,
Melanie Kirby-Allen,
Elliott Vichinsky,
James F Casella,
Ofelia A Alvarez,
Julio C Barredo,
Margaret T Lee, [......],
Abdullah Kutlar,
Kathleen M McKie,
Virgil McKie,
Nadine Odo,
Beatrice Gee,
Janet L Kwiatkowski, Gerald M Woods,
Thomas Coates,
Winfred Wang,
Robert J Adams
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ABSTRACT: Chronic blood transfusion is increasingly indicated in patients with sickle cell disease. Measuring resulting iron overload remains a challenge. Children without viral hepatitis enrolled in 2 trials for stroke prevention were examined for iron overload (STOP and STOP2; n = 271). Most received desferrioxamine chelation. Serum ferritin (SF) changes appeared nonlinear compared with prechelation estimated transfusion iron load (TIL) or with liver iron concentrations (LICs). Averaged correlation coefficient between SF and TIL (patients/observations, 26 of 164) was r = 0.70; between SF and LIC (patients/observations, 33 of 47) was r = 0.55. In mixed models, SF was associated with LIC (P = .006), alanine transaminase (P = .025), and weight (P = .026). Most patients with SF between 750 and 1500 ng/mL had a TIL between 25 and 100 mg/kg (72.8% +/- 5.9%; patients/observations, 24 of 50) or an LIC between 2.5 and 10 mg/g dry liver weight (75% +/- 0%; patients/observations, 8 of 9). Most patients with SF of 3000 ng/mL or greater had a TIL of 100 mg/kg or greater (95.3% +/- 6.7%; patients/observations, 7 of 16) or an LIC of 10 mg/g dry liver weight or greater (87.7% +/- 4.3%; patients/observations, 11 of 18). Although SF changes are nonlinear, levels less than 1500 ng/mL indicated mostly acceptable iron overload; levels of 3000 ng/mL or greater were specific for significant iron overload and were associated with liver injury. However, to determine accurately iron overload in patients with intermediately elevated SF levels, other methods are required. These trials are registered at www.clinicaltrials.gov as #NCT00000592 and #NCT00006182.
Blood 08/2009; 114(21):4632-8. · 9.90 Impact Factor
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Sharada A. Sarnaik,
James F. Casella,
Bruce A Barton,
Michele Afif,
Gladstone Airewele,
Brian W. Berman,
Francoise Bernaudin,
Thomas Coates,
Beng Fuh,
Helge Hartung, [......],
Charles T. Quinn,
Rupa Redding-Lallinger,
Melissa M. Rhodes,
Hernan Sabio,
Suzanne Saccente,
Charles Scher,
Paul Telfer,
Alexis A Thompson, Gerald M Woods,
Michael R. DeBaun
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ABSTRACT: Abstract 262 IntroductionThe most common cause of neurological injury in sickle cell anemia is silent cerebral infarcts (SCI). In the Silent Cerebral Infarct Multi-Center Clinical Trial (SIT Trial) cohort, we sought to identify risk factors associated with SCI. Patients and MethodsIn this cross-sectional study, we evaluated the clinical history, baseline laboratory values and performed magnetic resonance imaging of the brain. For those children with SCI-like lesions, a pediatric neurologist examined the child and neuroradiology and neurology committees adjudicated the presence of SCI. Children between the ages of 5 and 15 years with hemoglobin SS or S-beta{degrees} thalassemia and no history of overt strokes or seizure were evaluated. ResultsA total of 542 children were evaluated; 173 (31.9%) had SCI. The mean age of the children was 9.3 years, with 280 males (51.7%). In a multivariate logistic analysis, two covariates were significant: a single systolic blood pressure (SBP) obtained during a baseline well-visit, p = 0.015 and hemoglobin F (Hgb F) level obtained after three years of age, p = 0.038. Higher values of SBP and lower values of Hgb F increased the odds of SCI; Figure. Baseline values of white blood cell count, hemoglobin level, oxygen saturation, reticulocytes, pain, or ACS event rates were not associated with SCI. [IMG] /small/bld0010900030002.gif" ALT="Figure 1"> Figure. Joint effect of fetal hemoglobin and systolic blood -pressure on odds of silent cerebral infarct in 542 children with hemoglobin SS or S-beta{degrees}-thalassemia between 5 and 15 years of age. ConclusionSBP and Hgb F level are two previously unidentified risk factors for SCI in children with sickle cell disease. Modulation of SBP and Hgb F levels might decrease the risk of SCI. DisclosuresNo relevant conflicts of interest to declare.
Blood (ASH Annual Meeting Abstracts). 01/2009; 114(22):262-.
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ABSTRACT: Several analytical methods have been developed for the determination of arginase (l-arginine amidinohydrolase) activity in physiological samples. These methods are limited by the considerable effort and time required to obtain reliable and reproducible measurements. Here we describe a simple high-throughput colorimetric assay for the determination of arginase activity based on the ornithine-ninhydrin reaction. This method is an improvement over the original single cuvette assay developed by Chinard in that no boiling step is required. The turnaround time has been reduced, with improved precision and reproducibility. The method was extended to the determination of arginase activity in human leukemic (K562) cells and sickle erythrocytes. We believe that the method will find applications for routine analysis as well as for characterizing the action of novel and potent inhibitors on arginase activity.
Analytical Biochemistry 09/2008; 383(2):332-4. · 3.00 Impact Factor
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ABSTRACT: Increased levels of erythrocyte arginase activity are believed to play a key role in the pathogenesis of sickle cell disease (SCD). Because increased arginase activity has been implicated in the exacerbation of pulmonary hypertension in SCD, this enzyme is considered an important therapeutic target for identifying new drugs to treat and manage SCD and other inflammatory disorders. Although chloroquine (CQ) is prescribed as an anti-malarial and anti-rheumatoid drug, the mechanism of its anti-inflammatory activity is largely unknown. The present study found that CQ inhibited arginase in a dose-dependent manner, and also displayed a linear competitive inhibition on sickle erythrocyte arginase. The apparent K(M) values in the presence of inhibitor were considerably reduced at both physiological and slightly acidic pHs. Slope replots of the double reciprocal plots at pH 6.8 and 7.4 also indicated simple competitive inhibitory mechanism of CQ, and Ki values for CQ were within micromolar levels. To our knowledge, this is the first example of an anti-malarial and anti-inflammatory agent displaying competitive inhibition kinetics on arginase. The outcome of this study may provide a template for the rational design of specific agents either alone or in combination with CQ for the inhibition of arginase activity.
British Journal of Haematology 11/2007; 139(2):337-43. · 4.94 Impact Factor
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ABSTRACT: Nontuberculous mycobacteria (NTM) are ubiquitous in nature and have been implicated in skin/soft-tissue, pulmonary, middle ear, bone, and surgical/traumatic wound infections. Disseminated disease occurs infrequently and almost exclusively in the immunocompromised. We describe the first 2 reported cases of disseminated Mycobacterium fortuitum infection in teenagers with sickle hemoglobinopathy. Both had central venous catheters (CVCs), frequent admissions for vaso-occlusive painful episode and received hydroxyurea. Diagnosis was confirmed by multiple positive blood cultures and pulmonary dissemination occurred in both. Both had successful treatment after CVC removal and combination drug therapy. Positive cultures persisted in 1 patient due to drug resistance emphasizing the need for accurate susceptibility data. NTM infection should be added to the list of pathogens in sickle cell patients with CVCs and fever. Investigation for disseminated disease should be undertaken based on clinical signs and symptoms. Although some routine blood culture systems can identify NTM, specific mycobacterial blood culture is optimal. Removal of involved CVCs is essential and treatment of NTM must be guided by susceptibilities. As dissemination almost always occurs in those with impaired cellular immunity, human immunodeficiency virus testing should be performed. Hydroxyurea may be a risk factor for dissemination and needs further evaluation.
Journal of Pediatric Hematology/Oncology 11/2006; 28(10):678-81. · 1.16 Impact Factor
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Douglas J Scothorn,
Cynthia Price,
Daniel Schwartz,
Cindy Terrill,
George R Buchanan,
Wanda Shurney,
Ingrid Sarniak,
Robert Fallon,
Jen-Yih Chu,
Charles H Pegelow, [......],
Brian Berman,
Thomas Adamkiewicz,
Lewis L Hsu,
Kwaku Ohene-Frempong,
Kim Smith-Whitley,
Donald Mahoney,
J Paul Scott, Gerald M Woods,
Masayo Watanabe,
Michael R Debaun
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ABSTRACT: To test the hypothesis that children with sickle cell disease (SCD) who have an initial stroke temporally unrelated to another medical event are at higher risk for recurrent stroke than are children who had strokes temporally related to medical events.
A retrospective cohort study of children with SCD and stroke who received regularly scheduled blood transfusions for a minimum of 5 years was conducted. Medical records were examined for the documentation of antecedent or concurrent medical events (hypertension, acute chest syndrome, aplastic crisis, fever associated with infection, exchange transfusion) associated with physician contact within 14 days before the initial stroke.
A total of 137 pediatric patients from 14 centers were studied. Mean age at first stroke was 6.3 years (1.4 to 14.0 years) with mean follow-up of 10.1 years (5 to 24 years). Thirty-one (22%) patients had a second stroke (2.2 per 100 patient years); 26 patients had an identified medical or concurrent event associated with their initial stroke. None of these patients had recurrent stroke 2 or more years after the initial event. The remaining 111 patients had an ongoing risk of recurrent stroke (1.9 per 100 patient-years) despite long-term transfusions (P =.038).
The absence of an antecedent or concurrent medical event associated with an initial stroke is a major risk factor for subsequent stroke while receiving regular transfusions.
Journal of Pediatrics 04/2002; 140(3):348-54. · 4.11 Impact Factor
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Gerald M. Woods,
James H. Jorgensen,
Myron A. Waclawiw,
Clarice Reid,
Winfred Wang,
Charles H. Pegelow,
Zora R. Rogers,
Rathi V. Iyer,
C. Tate Holbrook,
Thomas R. Kinney,
Elliott Vichinsky,
Michael R. DeBaun,
Neil J. Grossman,
Marilyn D. Thomas,
John M. Falletta
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ABSTRACT: Purpose: To evaluate the consequences of prolonged prophylactic penicillin use on the rates of nasopharyngeal colonization with Streptococcus pneumoniae and the prevalence of resistant pneumococcal strains in children with sickle cell anemia.
Methods: Nasopharyngeal specimens were obtained from children with sickle cell anemia (Hb SS or Hb Sβ° thalassemia) at 10 teaching hospitals throughout the United States. These patients were participating in a prospective, randomized, placebo-controlled trial in which they were prescribed prophylactic penicillin before their fifth birthday and were randomized to prophylactic penicillin or placebo after their fifth birthday (PROPS II). The specimens were cultured for S. pneumoniae, and isolates were analyzed for antimicrobial susceptibility to nine commonly prescribed antimicrobial agents.
Results: Of the 226 patients observed, an average of 8.4 specimens were collected per patient. From 1,896 individual culture specimens, 5.5% of the specimens were positive for S. pneumoniae; 27% of patients had at least one positive culture. Nine percent of the study patients had at least one isolate of penicillin intermediate or resistant pneumococci. There was no significant difference in the percent of positive cultures for S. pneumoniae in those patients given penicillin prophylaxis after 5 years of age (4.1%) compared with those patients given placebo after 5 years of age (6.4%). Likewise, there was no significant difference (p = 0.298) in the percent of patients with at least one positive culture for S. pneumoniae in the group given prophylactic penicillin after 5 years of age (21.8%) compared with the group given placebo after 5 years of age (28.3%). There was no difference between the penicillin and placebo groups in the proportion of patients with penicillin intermediate or resistant pneumococci, but there was a trend toward increased carriage of multiply drug-resistant pneumococci in children > 5 years of age receiving prophylactic penicillin compared to children > 5 years of age receiving placebo. The increased colonization rate with multiply drug-resistant organisms of children > 5 years of age receiving penicillin prophylaxis is not statistically significant.
Conclusions: The potential for continued penicillin prophylaxis to contribute to the development of multiply resistant pneumococci should be considered before continuing penicillin prophylaxis in children with sickle cell anemia who are older than 5 years of age. Added to the published data from PROPS II, which demonstrated no apparent advantage to continue prophylaxis, the data support the conclusion that, for children with no history of invasive pneumococcal disease, consideration should be given to discontinue prophylactic penicillin after their fifth birthday.
Journal of Pediatric Hematology/Oncology 06/1997; 19(4):327-333. · 1.16 Impact Factor
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ABSTRACT: Impairment of nitric oxide bioavailability secondary to increased arginase activity and overproduction of reactive oxygen species (ROS) is thought to be a major cause of vascular complications in sickle cell disease (SCD). However, the role of ROS in the induction of arginase activity is unknown. This study investigated whether the mechanism of arginase activation involves the ROS produced during oxidative stress. Our study reveals that cysteine–iron dose-dependently stimulated arginase activity with a corresponding increase in OH radical formation. The OH radicals produced were significantly inhibited by salicylic acid derivatives and superoxide dismutase. Surprisingly, the inhibition of OH radicals parallels the inhibition of arginase activity, thus suggesting the role of cysteine–iron in the stimulation of arginase via the Fenton reaction. This is the first evidence demonstrating the participation of OH radicals in the stimulation of arginase activity, and thus provides novel avenues for therapeutic modalities in hemoglobinopathies and other inflammation-mediated diseases.
Biochemical and Biophysical Research Communications.
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ABSTRACT: Sickle cell disease (SCD) is a genetic disorder that is most prevalent among those of African American and Mediterranean descent. Hemoglobin SS is the most severe form of SCD and carries an increased risk for stroke. Although the initial treatment for stroke is an exchange transfusion, the use of routine, chronic transfusion therapy (CTT) has been shown to help prevent this neurological injury. The treatment plan is rigorous and time consuming, both of which impact one's quality of life (QoL). The purpose of this study was to explore QoL, from the child's perspective, as it is affected by CTT Semistructured interviews were performed on 10 children undergoing CIT: Five themes emerged from the data: (a) pain, (b) school issues, (c) disease knowledge, (d) transfusion therapy, and (e) having a stroke. Data from this study reveal that CTT does have an impact on QoL. This information is important to share with those making CTT treatment decisions.
Journal of Pediatric Oncology Nursing 21(4):207-13. · 0.70 Impact Factor
