[Morphological characteristics of osteopetrosis]. / Morphologische Veränderungen des Knochengewebes bei Osteopetrose.

Osteopetrosis is a rare inherited bone disorder characterized by increased bone density owing to failure in bone resorption by the osteoclasts. The disease is genetically and histologically heterogeneous with a wide spectrum of microscopic findings. The histology varies from cases with a total absence of osteoclasts to bone biopsies characterized by high numbers of enlarged multinucleated osteoclasts on a background of sclerotic cancellous bone with or without additional defect of mineralization of the bone matrix. Here we present typical cases of human osteopetrosis on the basis of bone biopsies with four distinct genotypes (mutations of TNFRSF11A, TCIRG1, CNCL7, KINDLIN-3 genes) and discuss genotype-phenotype relationships. Analyzing human bone biopsies of rare skeletal disorders might improve our understanding of bone metabolism with possible implications for the clinical management of other bone diseases.

The correct blood volume for paediatric blood cultures: a conundrum?

BACKGROUND: Bloodstream infections (BSIs) are a major cause of morbidity and mortality in paediatric patients. For fast and accurate diagnosis, blood culture (BC) is the reference standard. However, the procedure for blood sampling in paediatric patients, particularly the optimal blood volume, is the subject of controversy stemming from a lack of knowledge of the bacterial load and because of several obstacles such as low intravascular volume and the risk of causing anaemia. AIMS: The aim of this narrative review is to summarize current knowledge on blood sampling in paediatric patients for BC purposes, in particular blood volume and number and type of BC bottles needed for reasonable future guidelines/recommendations. SOURCES: A comprehensive literature search of PubMed, including all publications in English, was performed in June 2019 using the search terms 'blood culture', 'blood volume', 'bloodstream infection', 'diagnostic', 'paediatric' and/or 'sepsis'. CONTENT: The amount of inoculated blood determines the sensitivity, specificity and time to positivity of a BC, and low-level bacteraemia (≤10 cfu/mL) in paediatric patients is presumed to be more common than reported. Current approaches for 'adequate' blood volume for paediatric BC are mainly weight- or age-dependent. Of these recommendations, the scheme devised by Gaur and colleagues seems most appropriate and calls for a sample of 1-1.5 mL for children weighing <11 kg and 7.5 mL for a patient weight of 11-17 kg to be drawn into one BC bottle. Inclusion of a more detailed grading in the weight range 4-14 kg, as published by Gonsalves and colleagues, might be useful. IMPLICATIONS: This review could be important for future guidelines on paediatric BC collection and thus could contribute to improving patient management and lowering the economic and global health burden associated with BSI. Furthermore, upcoming molecular-based approaches with low sample volumes might be an interesting alternative.

Combination therapy of omega-3 fatty acids and acipimox for children with hypertriglyceridemia and acute lymphoblastic leukemia.

BACKGROUND: Lipemic alterations are commonly seen in pediatric patients with acute lymphoblastic leukemia (ALL) treated with corticosteroids and L-asparaginase. OBJECTIVE: In these children, hypertriglyceridemia rarely causes symptoms and mostly responds well to a low-fat diet. Only few patients demand further therapy, which is not clearly approved in the literature to date. Therefore, it may be important to compile generally accepted standard procedures for lipid-lowering therapy in the pediatric ALL population. METHODS: We performed a study on 119 newly diagnosed pediatric patients with ALL, all treated according to the ALL-BFM 2000 protocol at our institution between the years 2000 and 2009, to evaluate the incidence of hypertriglyceridemia and the efficacy of a combination therapy with omega-3 fatty acids and acipimox in hypertriglyceridemic patients who did not respond to diet. RESULTS: We observed hypertriglyceridemia in 34.5% of patients in this collective. In the majority, normalization of triglycerides was successfully managed by administration of a low-fat diet. However, 7.6% of patients (related to total study population) with hypertriglyceridemia did not show diminished lipid levels during diet and/or presented with symptoms such as abdominal pain, dyspnea, or anginal chest pain. In these cases, we performed a lipid-lowering combination therapy with omega-3 fatty acids and acipimox. We observed a prompt decline of serum triglycerides to normal values and an improvement of symptoms within days after onset of this therapy without occurrence of any side effects. CONCLUSION: In summary, the combination treatment with omega-3 fatty acids and acipimox could represent an alternative to other reported lipid-lowering therapies without severe adverse reactions.

Management of chronic immune thrombocytopenia in children and adolescents: lessons from an Austrian national cross-sectional study of 81 patients.

Chronic immune thrombocytopenia (cITP) is often associated with an underlying predisposition towards autoimmunity, recognition of which is relevant to guide treatment. International recommendations on diagnostic steps and therapeutic measures of cITP in childhood exist. However, due to the low prevalence (1-2/100,000) and a variation of availability of immunological and hematological tests and treatments across pediatric units, we postulated that these guidelines are not uniformly adhered to and that immune dysregulation syndromes remained undiscovered. To delineate the current management of children and adolescents with cITP in Austria, we performed a nationwide cross-sectional study. Between 2011 and 2014, 81 children with cITP were seen at seven centers (median age 8.75 years; range 1-17; female:male ratio 47:34) at 641 visits during 180 patient years after diagnosis of cITP (>12 months ITP duration). Additional diagnoses were noted, most frequently immune or autoimmune disorders, hematologic diseases, or infections (in 37.3%, including Evans syndrome, autoimmune lymphoproliferative syndrome, systemic lupus erythematosus, and Fanconi anemia), or other symptoms like bi- or pancytopenia (n=9), lymphoproliferation or granulomatous inflammation (n = 3). Both decision to treat as well as choice of treatment varied: smaller centers tended to observe more frequently, larger centers applied a pattern of treatment modalities that appeared to depend less on bleeding tendency than on center policy. More than 50% of therapeutic interventions occurred in bleedings scores ≤2 (of 5), suggesting a strong psychosocial intention to treat. Platelet increment upon 479 therapeutic interventions of eight types was evaluated, with multiple treatment approaches being pursued sequentially in refractory patients. These data confirm the hypothesis of heterogeneous diagnostic and therapeutic management of cITP in Austrian children and corroborate the need for (1) a precise panel of parameters to exclude underlying disorders and (2) for biomarkers to predict treatment response.

Emerging treatments in acute lymphoblastic leukemia.

Acute lymphoblastic leukemia (ALL) is a clonal proliferation of early B- and T-lymphocyte progenitors and results in the accumulation of leukemic blasts in the bone marrow and various extramedullary sites. It affects both children and adults, with peak prevalence between the ages of 2 to 5 years. Despite current treatment protocols achieving rapid cytoreduction in the vast majority of patients, serious acute and late complications are frequent and resistance to chemotherapy often develops. In contrast to the successes obtained with pediatric patients, treatment outcomes for adults remain poor with only 40% of patients being long-term survivors. Extensive research in the field of ALL has helped understand the mechanisms that control leukemic cells, facilitating the design of new drugs that specifically interfere with leukemic pathways and overcome chemo-resistance induced by common treatment regimens. Herein, we review the current status of the development of novel anti-leukemic agents, with emphasis on small molecular inhibitors that have already translated into clinical trials and are in the advanced stages of preclinical development. Challenges to successful development of each strategy are discussed.

High expression of the chemokine receptor CXCR4 predicts extramedullary organ infiltration in childhood acute lymphoblastic leukaemia.

Childhood acute lymphoblastic leukaemia (ALL) is a malignancy with the potential to infiltrate the liver, spleen, lymph nodes and brain. Such extramedullary presentation is important for understanding the biology of childhood ALL and also for developing new prognostic parameters. A potential mechanism in the trafficking of leukaemia cells is the interaction of the chemokine receptor CXCR4, which is expressed on ALL cells, and its ligand stromal cell-derived factor-1 (SDF-1), produced by stromal cells in bone marrow and extramedullary organs. Functionality of CXCR4 was demonstrated by a high correlation between cell surface density of CXCR4 and transendothelial migration of leukaemia blasts towards a gradient of SDF-1 (r = 0.73, P = 0.001). Inhibition of SDF-1-induced migration by an anti-CXCR4 monoclonal antibody (78.33 +/- 23.86% inhibition) evidenced the specificity of CXCR4 to SDF-1. In order to evaluate clinical significance of CXCR4 expression, lymphoblasts from the bone marrow of 73 patients with and without extramedullary organ infiltration were compared. Multiparameter flow cytometry revealed that lymphoblasts from patients with high extramedullary organ infiltration, defined as ultrasonographically measured enlargement of liver or spleen, expressed the CXCR4 receptor at higher fluorescence intensity (median 66.12 +/- 66.17) than patients without extramedullary organ infiltration (median 17.56 +/- 19.29; P < 0.001). Consequently, high expression of CXCR4 was strongly predictive for extramedullary organ involvement, independently of the peripheral lymphoblast count. Highest CXCR4 expression was seen in mature B ALL (median 102.74 +/- 92.13; P < 0.003), a disease characterized by a high incidence of extramedullary bulky disease. As high expression of the chemokine receptor CXCR4 predicts extramedullary organ infiltration in childhood ALL, we suggest that CXCR4 and its ligand play an essential role in extramedullary invasion.