Pulmonary embolism in pediatrics: A 10-year experience from a tertiary center in Brazil

ABSTRACT Introduction: Although still rare, pulmonary embolism (PE) in children has been increasing over the years. Data regarding this group of patients are still sparse, which contributes to the lack of standardized prophylaxis protocols and the misdiagnosis. This study aimed to determine the incidence of pediatric PE at a Brazilian tertiary hospital, describe clinical characteristics and identify possible risk factors. We also analyzed the diagnosis and management of PE. Methods: This was a retrospective review of tertiary Brazilian single-center data of all pediatric patients (0 - 18 years) with acute PE, diagnosed radiologically, from September 2009 to May 2019. Results: The incidence of PE was 3.3 cases per 10,000 hospitalized children. All the twenty-three cases had some risk factor identified and sixteen of them (69.5%) had more than one risk factor. The most important were central venous catheter (39.1%), malignancy (34.8%) and recent surgery (34.8%). Among the children with identifiable symptoms (69.5%), the most common was dyspnea (56.2%). Only one patient did not receive antithrombotic therapy because of the high bleeding risk and most patients (70.6%) were treated for 3 to 6 months. Among the nineteen patients alive at the end of the six-month follow-up, ten (52.6%) repeated the PE image control. Seven of them (70.0%) had complete or partial resolution of the thrombosis and none had worsening images. Conclusion: Our lower incidence than that of the current literature may reflect underdiagnosis due to low suspicion of PE. At least one risk factor was identified in all patients, which emphasizes the importance of increasing awareness of high-risk children.

Pulmonary embolism in pediatrics: A 10-year experience from a tertiary center in Brazil.

INTRODUCTION: Although still rare, pulmonary embolism (PE) in children has been increasing over the years. Data regarding this group of patients are still sparse, which contributes to the lack of standardized prophylaxis protocols and the misdiagnosis. This study aimed to determine the incidence of pediatric PE at a Brazilian tertiary hospital, describe clinical characteristics and identify possible risk factors. We also analyzed the diagnosis and management of PE. METHODS: This was a retrospective review of tertiary Brazilian single-center data of all pediatric patients (0 - 18 years) with acute PE, diagnosed radiologically, from September 2009 to May 2019. RESULTS: The incidence of PE was 3.3 cases per 10,000 hospitalized children. All the twenty-three cases had some risk factor identified and sixteen of them (69.5%) had more than one risk factor. The most important were central venous catheter (39.1%), malignancy (34.8%) and recent surgery (34.8%). Among the children with identifiable symptoms (69.5%), the most common was dyspnea (56.2%). Only one patient did not receive antithrombotic therapy because of the high bleeding risk and most patients (70.6%) were treated for 3 to 6 months. Among the nineteen patients alive at the end of the six-month follow-up, ten (52.6%) repeated the PE image control. Seven of them (70.0%) had complete or partial resolution of the thrombosis and none had worsening images. CONCLUSION: Our lower incidence than that of the current literature may reflect underdiagnosis due to low suspicion of PE. At least one risk factor was identified in all patients, which emphasizes the importance of increasing awareness of high-risk children.

Acrosomal alkalinization occurs during human sperm capacitation.

Mammalian sperm capacitation is a prerequisite for successful fertilization. Capacitation involves biochemical and physiological modifications of sperm as they travel through the female reproductive tract. These modifications prepare the sperm to undergo the acrosome reaction (AR), an acrosome vesicle exocytosis that is necessary for gamete fusion. Capacitation requires an increase in both intracellular calcium ([Ca2+]i) and pH (pHi). Mouse sperm capacitation is accompanied by acrosomal alkalinization and artificial elevation of the acrosome pH (pHa) is sufficient to trigger the AR in mouse and human sperm, but it is unknown if pHa increases naturally during human sperm capacitation. We used single-cell imaging and image-based flow cytometry to evaluate pHa during capacitation and its regulation. We found that pHa progressively increases during capacitation. The V-ATPase, which immunolocalized to the acrosome and equatorial segment, is mainly responsible for the acidity of the acrosome. It is likely that the regulation of V-ATPase is at least in part responsible for the progressive increase in pHa during capacitation. Acrosome alkalinization was dependent on extracellular HCO3- and Ca2+. Inhibition of the HCO3--dependent adenylyl cyclase and protein kinase A induced significant pHa changes. Overall, alkalinization of the acrosome may be a key step in the path toward the AR.

Prevalence and outcomes of thrombotic and hemorrhagic complications in pediatric acute promyelocytic leukemia in a tertiary Brazilian center

Abstract Introduction: Little attention is given to thrombosis associated with pediatric acute promyelocytic leukemia (APL). This study describes the thrombotic and hemorrhagic manifestations of APL in pediatric patients and evaluates their hemostasis, based on coagulation tests. Methods: Inclusion criteria were age 0-18 years and APL diagnosis between April 2005 and November 2017. Patients who had received blood transfusion prior to coagulation tests were excluded. Baseline coagulation tests, hematologic counts, and hemorrhagic/thrombotic manifestations were evaluated. Results: Median age was 10.7 years (1-15 years). The initial coagulation tests revealed a median Hgb of 8.3 g/dL (4.7-12.9 g/dL), median leucocyte count of 10.9 × 109/L (1.1-95.8 × 109/L), median platelet count of 31.8 × 109/L (2.0-109.0 × 109/L), median activated partial thromboplastin time (aPTT) of 31.7 s (23.0-50.4 s), median aPTT ratio of 1.0 (0.78-1.6), median thromboplastin time (PT) of 17.5 s (13.8-27.7 s), median PT activity of 62% (25-95 %), and median fibrinogen of 157.7 mg/dL (60.0-281.0 mg/dL). Three patients (13%) had thrombosis. At diagnosis, 21 patients (91.3%) had bruising, one patient (4.3%) had splenic vein and artery thrombosis and one patient (4.3%) presented without thrombohemorrhagic manifestations. During treatment, two patients (8.6%) had thrombosis. Conclusion: Knowledge of thrombosis in pediatric APL is important to determine its risk factors and the best way to treat and prevent this complication.

Prevalence and outcomes of thrombotic and hemorrhagic complications in pediatric acute promyelocytic leukemia in a tertiary Brazilian center.

INTRODUCTION: Little attention is given to thrombosis associated with pediatric acute promyelocytic leukemia (APL). This study describes the thrombotic and hemorrhagic manifestations of APL in pediatric patients and evaluates their hemostasis, based on coagulation tests. METHODS: Inclusion criteria were age 0-18 years and APL diagnosis between April 2005 and November 2017. Patients who had received blood transfusion prior to coagulation tests were excluded. Baseline coagulation tests, hematologic counts, and hemorrhagic/thrombotic manifestations were evaluated. RESULTS: Median age was 10.7 years (1-15 years). The initial coagulation tests revealed a median Hgb of 8.3 g/dL (4.7-12.9 g/dL), median leucocyte count of 10.9 × 109/L (1.1-95.8 × 109/L), median platelet count of 31.8 × 109/L (2.0-109.0 × 109/L), median activated partial thromboplastin time (aPTT) of 31.7 s (23.0-50.4 s), median aPTT ratio of 1.0 (0.78-1.6), median thromboplastin time (PT) of 17.5 s (13.8-27.7 s), median PT activity of 62% (25-95 %), and median fibrinogen of 157.7 mg/dL (60.0-281.0 mg/dL). Three patients (13%) had thrombosis. At diagnosis, 21 patients (91.3%) had bruising, one patient (4.3%) had splenic vein and artery thrombosis and one patient (4.3%) presented without thrombohemorrhagic manifestations. During treatment, two patients (8.6%) had thrombosis. CONCLUSION: Knowledge of thrombosis in pediatric APL is important to determine its risk factors and the best way to treat and prevent this complication.

Persistent symptoms and decreased health-related quality of life after symptomatic pediatric COVID-19: A prospective study in a Latin American tertiary hospital

OBJECTIVES: To prospectively evaluate demographic, anthropometric and health-related quality of life (HRQoL) in pediatric patients with laboratory-confirmed coronavirus disease 2019 (COVID-19) METHODS: This was a longitudinal observational study of surviving pediatric post-COVID-19 patients (n=53) and pediatric subjects without laboratory-confirmed COVID-19 included as controls (n=52) was performed. RESULTS: The median duration between COVID-19 diagnosis (n=53) and follow-up was 4.4 months (0.8-10.7). Twenty-three of 53 (43%) patients reported at least one persistent symptom at the longitudinal follow-up visit and 12/53 (23%) had long COVID-19, with at least one symptom lasting for >12 weeks. The most frequently reported symptoms at the longitudinal follow-up visit were headache (19%), severe recurrent headache (9%), tiredness (9%), dyspnea (8%), and concentration difficulty (4%). At the longitudinal follow-up visit, the frequencies of anemia (11% versus 0%, p=0.030), lymphopenia (42% versus 18%, p=0.020), C-reactive protein level of >30 mg/L (35% versus 0%, p=0.0001), and D-dimer level of >1000 ng/mL (43% versus 6%, p=0.0004) significantly reduced compared with baseline values. Chest X-ray abnormalities (11% versus 2%, p=0.178) and cardiac alterations on echocardiogram (33% versus 22%, p=0.462) were similar at both visits. Comparison of characteristic data between patients with COVID-19 at the longitudinal follow-up visit and controls showed similar age (p=0.962), proportion of male sex (p=0.907), ethnicity (p=0.566), family minimum monthly wage (p=0.664), body mass index (p=0.601), and pediatric pre-existing chronic conditions (p=1.000). The Pediatric Quality of Live Inventory 4.0 scores, median physical score (69 [0-100] versus 81 [34-100], p=0.012), and school score (60 [15-100] versus 70 [15-95], p=0.028) were significantly lower in pediatric patients with COVID-19 at the longitudinal follow-up visit than in controls. CONCLUSIONS: Pediatric patients with COVID-19 showed a longitudinal impact on HRQoL parameters, particularly in physical/school domains, reinforcing the need for a prospective multidisciplinary approach for these patients. These data highlight the importance of closer monitoring of children and adolescents by the clinical team after COVID-19.

Differences in children and adolescents with SARS-CoV-2 infection: a cohort study in a Brazilian tertiary referral hospital

OBJECTIVES: To compare demographic/clinical/laboratory/treatments and outcomes among children and adolescents with laboratory-confirmed coronavirus disease 2019 (COVID-19). METHODS: This was a cross-sectional study that included patients diagnosed with pediatric COVID-19 (aged <18 years) between April 11, 2020 and April 22, 2021. During this period, 102/5,951 (1.7%) of all admissions occurred in neonates, children, and adolescents. Furthermore, 3,962 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detection samples were processed in patients aged <18 years, and laboratory-confirmed COVID-19 occurred in 155 (4%) inpatients and outpatients. Six/155 pediatric patients were excluded from the study. Therefore, the final group included 149 children and adolescents (n=97 inpatients and 52 outpatients) with positive SARS-CoV-2 results. RESULTS: The frequencies of sore throat, anosmia, dysgeusia, headache, myalgia, nausea, lymphopenia, pre-existing chronic conditions, immunosuppressive conditions, and autoimmune diseases were significantly reduced in children and adolescents (p<0.05). Likewise, the frequencies of enoxaparin use (p=0.037), current immunosuppressant use (p=0.008), vasoactive agents (p=0.045), arterial hypotension (p<0.001), and shock (p=0.024) were significantly lower in children than in adolescents. Logistic regression analysis showed that adolescents with laboratory-confirmed COVID-19 had increased odds ratios (ORs) for sore throat (OR 13.054; 95% confidence interval [CI] 2.750-61.977; p=0.001), nausea (OR 8.875; 95% CI 1.660-47.446; p=0.011), and lymphopenia (OR 3.575; 95% CI 1.355-9.430; p=0.010), but also had less hospitalizations (OR 0.355; 95% CI 0.138-0.916; p=0.032). The additional logistic regression analysis on patients with preexisting chronic conditions (n=108) showed that death as an outcome was significantly associated with pediatric severe acute respiratory syndrome (SARS) (OR 22.300; 95% CI 2.341-212.421; p=0.007) and multisystem inflammatory syndrome in children (MIS-C) (OR 11.261; 95% CI 1.189-106. 581; p=0.035). CONCLUSIONS: Half of the laboratory-confirmed COVID-19 cases occurred in adolescents. Individuals belonging to this age group had an acute systemic involvement of SARS-CoV-2 infection. Pediatric SARS and MIS-C were the most important factors associated with the mortality rate in pediatric chronic conditions with COVID-19.

Cell Competition, the Kinetics of Thymopoiesis, and Thymus Cellularity Are Regulated by Double-Negative 2 to 3 Early Thymocytes.

Cell competition in the thymus is a homeostatic process that drives turnover. If the process is impaired, thymopoiesis can be autonomously maintained for several weeks, but this causes leukemia. We aimed to understand the effect of cell competition on thymopoiesis, identify the cells involved, and determine how the process is regulated. Using thymus transplantation experiments, we found that cell competition occurs within the double-negative 2 (DN2) and 3 early (DN3e) thymocytes and inhibits thymus autonomy. Furthermore, the expansion of DN2b is regulated by a negative feedback loop that is imposed by double-positive thymocytes and determines the kinetics of thymopoiesis. This feedback loop affects the cell cycle duration of DN2b, in a response controlled by interleukin 7 availability. Altogether, we show that thymocytes do not merely follow a pre-determined path if provided with the correct signals. Instead, thymopoiesis dynamically integrates cell-autonomous and non-cell-autonomous aspects that fine-tune normal thymus function.

Thrombolytic therapy in preterm infants: Fifteen-year experience.

OBJECTIVE: To report a single-center experience with thrombolytic therapy using recombinant tissue plasminogen activator (rt-PA) in preterm neonates with severe thrombotic events, in terms of thrombus resolution and bleeding complications. STUDY DESIGN: This retrospective study included 21 preterm neonates with severe venous thrombotic events admitted to the neonatal intensive care unit, identified in our pharmacy database from January 2001 to December 2016, and treated with rt-PA until complete or partial clot lysis, no-response or bleeding complications. Our primary outcome was thrombus resolution. RESULTS: Twenty-one preterm neonates were treated with rt-PA for an average of 2.9 cycles. Seventeen patients (80.9%) had superior vena cava thrombosis and superior vena cava syndrome. All patients had a central venous catheter, parenteral nutrition, mechanical ventilation, and sepsis. Fifteen patients (71.4%) were extremely preterm, 11 (52.4%) were extremely low birth weight, and seven (33.3%) were very low birth weight. The patency rate was 85.7%, complete lysis occurred in 11 (52.4%) patients, and partial lysis in seven (33.3%). Minor bleeding occurred in five (23.8%) patients, three patients (14.2%) had clinically relevant nonmajor bleeding events, and major bleeding occurred in six (28%) patients. CONCLUSION: In this study, the rate of thrombus resolution in preterm neonates treated with rt-PA were similar to the percentages reported in children and adolescents, with a high rate of bleeding. Therefore, rt-PA thrombolytic therapy should only be considered as a treatment option for severe life-threatening thrombosis in premature neonates for whom the benefits of the thrombolytic treatment outweigh the risks of bleeding.

Latent and Overt Polyautoimmunity in Children and Adolescents With Immune Thrombocytopenia.

Autoantibodies are biomarkers for autoimmune disease diagnosis, monitoring, and prediction. Therefore, this study established the frequency of latent and overt polyautoimmunity in children and adolescents with >6 months of diagnosis of immune thrombocytopenia (ITP). Forty-seven patients with chronic or persistent disease had non-organ-specific and organ-specific autoantibodies assessed. Frequency of latent polyautoimmunity was 36.2%, and, of overt polyautoimmunity, it was 4.3%. Of ITP patients with latent polyautoimmunity, 52.9% were positive for antinuclear antibody (ANA), 47.1% for autoantibodies other than ANA, and 64.7% for multiple autoantibodies. In addition, patients with latent polyautoimmunity and those positive for ANA were significantly older at disease onset. Both ITP patients positive and negative for autoantibodies reported family members with autoimmune diseases. The autoantibodies observed were as follows: ANA, anti-dsDNA, anti-SSA/Ro, IgM aCL, anti-GAD, anti-IA2, anti-IAA, anti-TG, anti-TPO, anti-LKM1, and SMA. Of ITP patients with overt polyautoimmunity, 1 was diagnosed with type 1 diabetes mellitus and the other with thyroiditis. In conclusion, children and adolescents with ITP present high frequency of latent and overt polyautoimmunity even for autoantibodies other than ANA. Therefore, ANA and other non-organ-specific and organ-specific autoantibodies should be considered for assessment during ITP patients' follow-up.

Venous thromboembolism in childhood: where is Brazil after 20 years?

Abstract Due to the longer survival of critically ill children, venous thromboembolism is a problem which is becoming increasingly recognized in pediatric practice. In the last decades, several international studies have been published, shedding a light upon the epidemiology of this disease during childhood. These data show peculiarities in the clinical presentation and the significant morbidity and mortality. The new "epidemic of thrombosis" in pediatric hospitals points toward the urgent need for specific treatment and prevention protocols targeting this population. In Brazil, knowledge regarding this disease remains scarce. The lack of epidemiological data impacts both the clinical care and the design of specific public policies in the field. Thus, a national registry of pediatric venous thromboembolism is relevant to the proposal of an appropriate plan of action to create a qualified net of assistance. The improvement in educational initiatives related to the field of Pediatric Hemostasis is also very important. In this review, we have updated the epidemiological, clinical and therapeutic aspects of the disease, as well as the prevention strategies.

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome as a Hyper-Regulated Immune System Driven by an Interplay Between Regulatory T Cells and Chronic Human Herpesvirus Infections.

Autoimmunity and chronic viral infections are recurrent clinical observations in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS), a complex disease with an unknown cause. Given these observations, the regulatory CD4+ T cells (Tregs) show promise to be good candidates for the underlying pathology due to their capacity to suppress the immune responses against both self and microbial antigens. Here, we discussed the overlooked role of these cells in the chronicity of Human Herpes Virus 6 (HHV6), Herpes Simplex 1 (HSV1), and Epstein-Barr virus (EBV), as often reported as triggers of ME/CFS. Using simulations of the cross-regulation model for the dynamics of Tregs, we illustrated that mild infections might lead to a chronically activated immune responses under control of Tregs if the responding clone has a high autoimmune potential. Such infections promote persistent inflammation and possibly fatigue. We then hypothesized that ME/CFS is a condition characterized by a predominance of this type of infections under control of Tregs. In contrast, healthy individuals are hypothesized to trigger immune responses of a virus-specific clone with a low autoimmune potential. According to this hypothesis, simple model simulations of the CD4+ T-cell repertoire could reproduce the increased density and percentages of Tregs observed in patients suffering from the disease, when compared to healthy controls. A deeper analysis of Tregs in the pathogenesis of ME/CFS will help to assess the validity of this hypothesis.

Síndrome de prader willi: o que o pediatra geral deve fazer - uma revisão / Prader-willi syndrome: what is the general pediatrician supposed to do? - a review

RESUMO Objetivo: Realizar uma revisão sobre a Síndrome de Prader-Willi (SPW) com base nas publicações mais recentes e fornecer recomendações ao pediatra geral para diagnóstico precoce e seguimento. Fonte de dados: Artigos publicados nas bases Pubmed e SciELO. A pesquisa não foi limitada a um período e incluiu todos os artigos das bases de dados. Síntese dos dados: A SPW é uma síndrome genética rara, resultante da perda do imprinting gênico expresso no cromossomo paterno 15q11-q13, sendo caracterizada por alterações endocrinológicas, como deficiência de hormônio de crescimento, obesidade, insuficiência adrenal central, hipotireoidismo, hipogonadismo, além de alterações comportamentais e déficit intelectual. Há outras comorbidades associadas, como distúrbios de sono, escoliose, constipação, problemas dentários e alterações de coagulação. O protocolo de seguimento da SPW do Instituto da Criança da Universidade de São Paulo se baseia em quarto pilares principais: dieta, exercício físico, terapia com hormônio de crescimento humano recombinante (rhGH) e manejo comportamental e cognitivo. A dieta deve ser restrita a 900 kcal/dia, de acordo com a Pirâmide Alimentar do Prader-Willi, e o exercício físico deve ser diário, aeróbico e postural. A terapia com rhGH é fortemente recomendada pela literatura científica internacional e deve ser iniciada assim que for realizado o diagnóstico da síndrome. O manejo do comportamento é realizado com estratégias para estabelecer rotina e regras. Conclusões: Se a SPW se tornar mais familiar ao pediatra geral, o diagnóstico e o tratamento começarão mais precocemente, o que irá melhorar a qualidade de vida e os cuidados desses pacientes.

ABSTRACT Objective: To carry out a review about Prader-Willi Syndrome based on the most recent data about the subject and to give recommendation for the general pediatricians for early diagnoses and follow-up. Data sources: Scientific articles in the PubMed and SciELO databases. The research was not limited to a specific time period and included all articles in such databases. Data synthesis: The Prader-Willi Syndrome (PWS) is a rare genetic disorder resulting from the loss of imprinted gene expression within the paternal chromosome 15q11-q13. PWS is characterized by endocrine abnormalities, such as growth hormone (GH) deficiency, obesity, central adrenal insufficiency, hypothyroidism, hypogonadism and complex behavioral and intellectual difficulties. PWS individuals also may present other comorbidities, such as sleep disorders, scoliosis, constipation, dental issues and coagulation disorders. The follow-up protocol of the Children's Institute at Universidade de São Paulo is based on four main pillars: diet, exercise, recombinant human growth hormone (rhGH) therapy and behavioral and cognitive issues. The diet must include a caloric restriction of 900 kcal/day, according to the Prader-Willi Eating Pyramid and exercise plan is focused on daily aerobic exercises and postural therapy. The rhGH therapy is highly recommended by the international scientific literature and must be started as soon as the diagnostic is made. The management of behavioral issues is based on strategies to establish routine and rules. Conclusions: If the general pediatrician becomes more familiar with PWS, the diagnosis and treatment will start earlier, which is essential to improve the quality of life and care for these individuals.

Characterization of vitamin K-dependent carboxylase mutations that cause bleeding and nonbleeding disorders.

Vitamin K-dependent coagulation factors deficiency is a bleeding disorder mainly associated with mutations in γ-glutamyl carboxylase (GGCX) that often has fatal outcomes. Some patients with nonbleeding syndromes linked to GGCX mutations, however, show no coagulation abnormalities. The correlation between GGCX genotypes and their clinical phenotypes has been previously unknown. Here we report the identification and characterization of novel GGCX mutations in a patient with both severe cerebral bleeding disorder and comorbid Keutel syndrome, a nonbleeding malady caused by functional defects of matrix γ-carboxyglutamate protein (MGP). To characterize GGCX mutants in a cellular milieu, we established a cell-based assay by stably expressing 2 reporter proteins (a chimeric coagulation factor and MGP) in HEK293 cells. The endogenous GGCX gene in these cells was knocked out by CRISPR-Cas9-mediated genome editing. Our results show that, compared with wild-type GGCX, the patient's GGCX D153G mutant significantly decreased coagulation factor carboxylation and abolished MGP carboxylation at the physiological concentration of vitamin K. Higher vitamin K concentrations can restore up to 60% of coagulation factor carboxylation but do not ameliorate MGP carboxylation. These results are consistent with the clinical results obtained from the patient treated with vitamin K, suggesting that the D153G alteration in GGCX is the causative mutation for both the bleeding and nonbleeding disorders in our patient. These findings provide the first evidence of a GGCX mutation resulting in 2 distinct clinical phenotypes; the established cell-based assay provides a powerful tool for studying the clinical consequences of naturally occurring GGCX mutations in vivo.

Outcome of children with severe acquired aplastic anemia treated with rabbit antithymocyte globulin and cyclosporine A, / Resultado de crianças com anemia aplástica grave adquirida tratadas com globulina antitimocítica de coelho e ciclosporina A,

Objective: To evaluate the outcome of children with severe acquired aplastic anemia treated with rabbit antithymocyte globulin and cyclosporine as first-line treatment at this institution. Methods: Retrospective analysis of 26 pediatric patients with aplastic anemia, treated between 1996 and 2011 with rabbit antithymocyte globulin plus cyclosporine. Results: The overall response rate at six months was 34.6% (9/26), and the cumulative incidence of relapse was 26.5% (95% confidence interval [CI]: 1.4%-66%) at 5 years. The cumulative incidence of clonal evolution after immunosuppressive therapy was 8.3% (95% CI: 0.001%-53.7%) at five years with both clonal evolutions in non-responders who acquired monosomy 7 karyotype. The overall survival at five years was 73.6% (95% CI: 49.2%-87.5%). Conclusions: The present results confirm the poor response rate with rabbit antithymocyte globulin as first therapy in pediatrics patients, similar to what has been reported for patients of all ages. This confirmation is problematic in Brazil, given the lack of horse antithymocyte globulin in many markets outside the United States. .

Objetivo: Avaliar o resultado de crianças com anemia aplástica grave adquirida tratadas com globulina antitimocítica de coelho e ciclosporina como tratamento inicial em nosso instituto. Métodos: Análise retrospectiva de 26 pacientes pediátricos com anemia aplástica tratados entre 1996 e 2011 com globulina antitimocítica de coelho e ciclosporina. Resultados: A taxa de resposta geral em seis meses foi de 34,6% (9/26), e a incidência acumulada de recorrência foi de 26,5% (intervalo de confiança [IC] de 95%,1,4%-66%) em cinco anos. A incidência acumulada de evolução clonal após a terapia imunossupressora foi de 8,3% (IC 95%, 0,001%-53,7%) em cinco anos, com ambas as evoluções clonais em pacientes sem resposta que adquiriram o cariótipo com monossomia 7. A sobrevida geral em cinco anos foi de 73,6% (IC 95%, 49,2%-87,5%). Conclusões: Nossos resultados confirmam a baixa taxa de resposta com globulina antitimocítica de coelho como terapia inicial em pacientes pediátricos, da mesma forma como relatado para pacientes de todas as idades. Essa confirmação é problemática em nosso país devido à falta de globulina antitimocítica de cavalo em muitos mercados fora dos Estados Unidos, incluindo o Brasil. .

Outcome of children with severe acquired aplastic anemia treated with rabbit antithymocyte globulin and cyclosporine A.

OBJECTIVE: To evaluate the outcome of children with severe acquired aplastic anemia treated with rabbit antithymocyte globulin and cyclosporine as first-line treatment at this institution. METHODS: Retrospective analysis of 26 pediatric patients with aplastic anemia, treated between 1996 and 2011 with rabbit antithymocyte globulin plus cyclosporine. RESULTS: The overall response rate at six months was 34.6% (9/26), and the cumulative incidence of relapse was 26.5% (95% confidence interval [CI]: 1.4%-66%) at 5 years. The cumulative incidence of clonal evolution after immunosuppressive therapy was 8.3% (95% CI: 0.001%-53.7%) at five years with both clonal evolutions in non -responders who acquired monosomy 7 karyotype. The overall survival at five years was 73.6% (95% CI: 49.2%-87.5%). CONCLUSIONS: The present results confirm the poor response rate with rabbit antithymocyte globulin as first therapy in pediatrics patients, similar to what has been reported for patients of all ages. This confirmation is problematic in Brazil, given the lack of horse antithymocyte globulin in many markets outside the United States.

A Novel Quantitative Fluorescent Reporter Assay for RAG Targets and RAG Activity.

Recombination-Activating Genes (RAG) 1 and 2 form the site specific recombinase that mediates V(D)J recombination, a process of DNA editing required for lymphocyte development and responsible for their diverse repertoire of antigen receptors. Mistargeted RAG activity associates with genome alteration and is responsible for various lymphoid tumors. Moreover several non-lymphoid tumors express RAG ectopically. A practical and powerful tool to perform quantitative assessment of RAG activity and to score putative RAG-Recognition signal sequences (RSS) is required in the fields of immunology, oncology, gene therapy, and development. Here we report the detailed characterization of a novel fluorescence-based reporter of RAG activity, named GFPi, a tool that allows measuring recombination efficiency (RE) by simple flow cytometry analysis. GFPi can be produced both as a plasmid for transient transfection experiments in cell lines or as a retrovirus for stable integration in the genome, thus supporting ex vivo and in vivo studies. The GFPi assay faithfully quantified endogenous and ectopic RAG activity as tested in genetically modified fibroblasts, tumor derived cell lines, developing pre-B cells, and hematopoietic cells. The GFPi assay also successfully ranked the RE of various RSS pairs, including bona fide RSS associated with V(D)J segments, artificial consensus sequences modified or not at specific nucleotides known to affect their efficiencies, or cryptic RSS involved in RAG-dependent activation of oncogenes. Our work validates the GFPi reporter as a practical quantitative tool for the study of RAG activity and RSS efficiencies. It should turn useful for the study of RAG-mediated V(D)J and aberrant rearrangements, lineage commitment, and vertebrate evolution.

Púrpura trombocitopênica trombótica na apresentação de pacientes com lúpus eritematoso sistêmico juvenil / Thrombotic thrombocytopenic purpura at presentation of juvenile systemic lupus erythematosus patients

Púrpura trombocitopênica trombótica (PTT) é uma alteração hematológica rara e com risco de morte, caracterizada por trombocitopenia, anemia hemolítica microangiopática e alterações neurológicas e/ou renais. A PTT foi descrita em raros pacientes com lúpus eritematoso sistêmico juvenil (LESJ) e, até onde se sabe, a prevalência dessa manifestação em uma população de lúpus pediátrico ainda não foi estudada. Assim, entre janeiro de 1983 e dezembro de 2010, revisamos os prontuários de 5.508 pacientes acompanhados na Unidade de Reumatologia Pediátrica do nosso hospital universitário. Foram identificados 279 (5,1%) casos de LESJ que preencheram os critérios de classificação do American College of Rheumatology. Dois destes (0,7%) apresentavam PTT, ambos no início do LESJ, e foram aqui descritos. Os dois pacientes tinham febre, anemia hemolítica microangiopática (com esquizócitos no sangue periférico) e trombocitopenia. O paciente do gênero masculino apresentava hemiparesia e proteinúria, e a paciente do gênero feminino tinha cefaleia persistente e hematúria. Ambos foram tratados com metilprednisolona endovenosa e plasmaferese quando do diagnóstico de PPT. Após tratamento, não houve recidiva da PTT, e hematócritos, contagens de plaquetas e níveis de desidrogenase lática permaneceram normais. Em conclusão, a PTT é uma rara e grave manifestação no início do LESJ. Os casos relatados reforçam a importância de um diagnóstico precoce e de uma terapia agressiva em pacientes com PTT, devido à sua alta morbidade.

Thrombotic thrombocytopenic purpura (TTP) is a rare and life-threatening hematological abnormality characterized by thrombocytopenia and microangiopathic hemolytic anemia, with neurological abnormalities and/or renal disease. TTP has been rarely reported in juvenile systemic lupus erythematosus (JSLE) patients and, to our knowledge, its prevalence in a paediatric lupus population has not been studied. Therefore, from January 1983 to December 2010, we reviewed the charts of 5,508 patients followed-up at the Paediatric Rheumatology Unit of our university hospital. We identified 279 (5.1%) JSLE cases that met the American College of Rheumatology classification criteria. Two (0.7%) of them had TTP, both at JSLE onset, and were described herein. Both patients had fever, microangiopathic hemolytic anemia (with schistocytes in blood smears), and thrombocytopenia. The male patient had hemiparesis and proteinuria and the female patient had persistent headache and hematuria. Both were treated with intravenous methylprednisolone and courses of plasma exchange therapy at TTP diagnosis. After treatment, TTP did not recur and their hematocrit, platelet count, and lactic dehydrogenase remained normal. In conclusion, TTP is a rare and severe manifestation at JSLE onset. The case reports reinforce the importance of early diagnosis and early aggressive treatment for patients with TTP, due to its high morbidity.

Deficiência congênita de fator X: quando pensar? / Congenital factor X deficiency: when thinking?

Objetivo: Descrever o caso de um lactente portador de deficiência congênita de fator X e discutir o diagnóstico diferencial dessa coagulopatia rara. Relato do caso: Lactente, 54 dias de vida, sexo masculino, foi encaminhado paraavaliação hematológica devido a episódios prévios de hemorragia de etiologia a esclarecer. No segundo dia de vida, apresentou epistaxe e aumento do perímetro cefálico e, na segunda semana de vida, apresentou enterorragia. Foram realizados examesque evidenciaram TP e TTPA prolongados e antecedentes familiares sugestivos de diátese hemorrágica. Em nosso serviço, foram descartadascausas adquiridas que poderiam justificar o prolongamento dos tempos de coagulação (deficiência de vitamina K, infecção, hepatopatias) e também foram descartados sangramentos emoutros locais (sistema nervoso central e abdome). As dosagens dos fatores de coagulação II e V foram normais, sendo detectados níveis de fator X inferioresa 1% (FX < 1%), evidenciando deficiência grave desta proteína. Durante a investigação, o paciente apresentou novo episódio de enterorragia, sem descompensação hemodinâmica e recebeu plasma fresco congelado. Atualmente, está em seguimento ambulatorial, em uso profilático de concentrado de complexo protrombínico, sem manifestaçõeshemorrágicas. Conclusão: As coagulopatias congênitas são doenças hemorrágicas resultantes da deficiência quantitativa ou qualitativa de umaou mais das proteínas plasmáticas da coagulação. Os pacientes acometidos podem apresentar sangramentos de gravidade variável, espontâneosou pós-traumáticos, presentes ao nascimento ou diagnosticados ocasionalmente. Estas coagulopatiassão caracterizadas por herança genética, quadro clínico e laboratorial distintos entre si e, entre elas, as hemofilias e a doença de Von Willebrand são as mais comuns. São consideradas coagulopatias raras as deficiências de fatores I, II, V,...

Objective: To describe the case of an infant with congenital factor X deficiency and to discuss the differential diagnosis of other rare coagulopathies. Case report: Infant, 54-day-old male was referred for hematologic evaluation due to previous episodes of bleeding of unknown etiology. On the second day of life, he had epistaxis and increased head circumference and, in the second week of life, had rectal bleeding. Laboratory assays were performed and showed prolonged PT and APTT and family history suggestive of bleeding disorders. In our department, other acquired causes that could justify the prolongation of clotting time (vitaminK deficiency, infection, liver disease) were excluded and bleeding were also evaluated at other sites (central nervous system and abdomen). The levels of coagulation factors II and V were normal and detected levels of factor X less than 1% (FX<1%),suggesting serious deficiency of this protein. During the investigation, the patient presented a new episode of rectal bleeding, without hemodynamicinstability, and received fresh frozen plasma. He is currently in follow-up, receiving prophylactic prothrombin complex concentrate, without hemorrhagic manifestations. Conclusion: the congenital coagulopathies are bleeding disorders resulting from a quantitative or qualitative deficiency of one or more of the plasma procoagulant protein. The affected patients may have bleeding of varying sev rity, spotaneous or post traumatic, present at birthor diagnosed occasionally. These bleding disorders are characterized by specific genetic inheritance and clinical and laboratory characteristics. Amonginherited bleedingdisorders, the hemophilia and Von Willebrand disease are the most common. The deficienciesof factors I, II, V, VII, X and XIII are considered rare coagulation disorders and the differential diagnosis among these diseases is essential to guideappropriate therapy. In cases of severe deficiency of factor X, as patients may have...